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Desmond Tutu arudishwa Hospital

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Hali bado ni tete kwa aliyewahi kuwa mshindi wa tuzo ya Nobel Askofu Demond Tutu baada ya kurejeshwa tena hospitalini kwa ajili ya kuendelea na matibabu. Askofu huyo lutoka nchini Afrika Kusini aliruhusiwa kurejea nyumbani baada ya afya yake kuonekana kuimarika wiki iliyopita, lakini ghafla hali ya ugonjwa ilimrudia tena hivyo na kurejeshwa hospitalini. Kwa muda mrefu Askofu Tutu mwenye umri wa miaka 83 amekuwa akisumbuliwa na maradhi ya saratani, na sasa yupo kwenye uangalizi mkubwa wa madaktari wanaoendelea kumtibu.

[via LEKULE]

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Hofu Yatanda Kwenye Kambi Ya Everton

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Hofu imetanda katika kambi ya maandalizi ya klabu ya Everton baada ya mshambuliaji wa klabu hiyo Romelu menama Lukaku, kuumia katika mchezo wa kujipima nguvu dhidi ya Dundee Utd uliochezwa usiku wa kuamkia hii leo. Lukaku alishindwa kumaliza mchezo huo, baada ya kupata maumivu ya nyama za paja, hali ambayo ilimsababisha kutoka uwanjani na nafasi yake kuchukuliwa na mchezaji mwingine. Taarifa kutoka Goodson Park, zinasema kwamba mshambuliaji huyo hii leo atafanyiwa vipimo ili kujua ameumia kiasi gani, na kama atakuwa na matarajio hafifu ya kurejea mapema kuna hati hati akaukosa mwanzo wa msimu wa ligi ya nchini England ambayo itaanza kutimua vumbi lake mwishoni mwa juma lijalo. Meneja wa Everton Roberto Martinez amesema hana budi kufanya subra ya kujua matokeo ya vipimo vywa mshambuliaji huyo, ambayo yatapatikana muda mchache kuanzia sasa na ndipo atakuwa na lolote la kuzungumza kuelekea mwanzoni mwa msimu. Tayari meneja huyo kutoka nchini Hispania ameshawapoteza Gerard Deulofeu pamoja na Steven Pienaar baada ya kupatwa na maumivu wa nyama za paja katika michezo iliyopita ya kujipima nguvu, na tayari imedhihirika wawili hao hawatokau sehemu ya kikosi cha Everton mwanzoni mwa msimu. Katika mchezo uliocheza usiku wa kuamkia hii leo, Everton waliibuka na ushindi wa mabao mawili kwa sifuri yaliyofungwa na Ross Barkley pamoja na Conor McAleny.

[via LEKULE]

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Star wa ‘series’ ya ‘Empire’ kushtakiwa na mtalaka wake.

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Terrence Howard ni muigizaji aliyejipatia umaarufu mkubwa baada ya kuigiza tamthiliya inayopendwa duniani kwa sasa ‘Empire’ akitumia jina la Lucios. Kwa mujibu wa mtandao wa TMZ, inaonekana majanga na mizengwe mingi inaendelea kumuandama na sasa kuna hili la kutaka kushtakiwa na mkewe wa zamani Michelle Ghent kufungua kesi kutokana na kipigo alichokuwa akipokea. Mwanamke huyo anadai mwaka 2013 wakati wakiishi Costa Rica, Terrence alikuwa akimpa kichapo cha ‘mbwa mwizi’ akimkaba shingoni, kumbamiza bafuni na kumfanyia vitendo vingi vya kinyama. Michelle anafuata sharia za baraza la kijinsia ili kupata utaratibu mzuri wa kuendesha kesi hiyo.

[via LEKULE]

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Lowassa, Ukawa uamuzi mgumu

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Dar es Salaam.  Siku moja baada ya Waziri Mkuu wa zamani, Edward Lowassa kutangaza kuhama CCM na kujiunga na Ukawa kupitia Chadema, wasomi na wachambuzi wa masuala ya siasa wamesema pande hizo mbili zimefanya uamuzi mgumu ambao utanufaisha kila upande. Profesa wa Chuo Kikuu Ruaha (Rucu), Gaudence Mpangala alisema uamuzi huo wa Lowassa ambaye alitangaza kujiunga na Chadema na kufafanua kuwa amejiunga na chama hicho kikuu cha upinzani kutekeleza azma yake ya kuwakomboa Watanzania na kuendeleza safari ya matumaini ni uamuzi mgumu. Alisema: “Lowassa amefanya uamuzi mgumu kutoka CCM lakini hata wapinzani wamefanya uamuzi mgumu kumpokea.” Alisema sababu kubwa ya Chadema kukubali kumpokea Lowassa ambaye leo anatarajiwa kuchukua fomu kuwania urais, wakati ilikuwa inamtuhumu kwa ufisadi inatokana na mwanasiasa huyo kuwa na watu wengi wanaomuunga mkono, hali ambayo itaibua ushindani mpya katika siasa nchini. Ni faida zaidi Profesa Mpangala alisema pamoja na Lowassa kutuhumiwa na viongozi wa vyama vinavyounda Ukawa kwa ufisadi, uwepo wake ndani ya umoja una faida zaidi kuliko hasara. “Faida ya Lowassa kwenda Ukawa ni kubwa zaidi kuliko hasara ya kuendelea kumpinga na kumtuhumu kwa ufisadi. Ukawa wanatambua kuwa uwepo wa Lowassa utawapa kura nyingi katika uchaguzi ujao,” alisema. Profesa huyo alisema si jambo la ajabu kwa mwanasiasa kuhama chama, huku akitolea mfano mwaka 1995 jinsi Augustine Mrema alivyohama CCM kwenda NCCR kuwa, “Kama si nguvu ya Mwalimu Julius Nyerere pengine angekuwa rais,” alisema. Mhadhiri wa Sayansi ya Siasa katika Chuo Kikuu Huria (OUT), Dk Emmanuel Malya alisema katika siasa kinachotazamwa zaidi ni nafasi, na kwamba katika siasa hakuna rafiki wala adui wa kudumu. “Ila ujio wa Lowassa Chadema lazima utazamwe, ni lazima chama hiki (Chadema) kimtazame kiongozi huyo anakuja na kitu gani? Pia, CCM nao hata kama hawatasema wazi, lakini kuondoka kwa Lowassa kutawatikisa kidogo,” alisema. Dk Malya alisema Lowassa alikuwa kiongozi katika Serikali iliyoundwa na CCM, hivyo ni lazima aeleze kilichomshinda kukifanya wakati huo na sababu za kutaka kuyafanya yaliyomshinda akiwa ndani ya Ukawa. Mhadhiri mwingine wa Sayansi ya Siasa wa Chuo Kikuu Dar es Salaam, Richard Mbunda alisema: “Ukitazama kwa makini utagundua kila mmoja anambeba mwenzake, yaani Lowassa anaibeba Chadema na Ukawa na wao pia wanambeba yeye.” Alisema kama waziri mkuu huyo wa zamani atagombea urais kwa tiketi ya Chadema ni wazi kuwa mpambano utakuwa mkali kati yake na mgombea urais wa CCM, Dk John Magufuli kwa maelezo kuwa kuna baadhi ya mambo wanaendana. “Mtaji wa chama cha siasa ni watu na lengo kuu ni kuongoza nchi. Hakuna adui wa kudumu katika siasa. Kilichotokea ni jambo la kawaida tu ila tu watu wamestushwa maana hawakutegemea Lowassa kuwa atakihama CCM,” alisema. Lissu: Kwanini tumemkubali Mwanasheria Mkuu wa Chadema, Tundu Lissu ametaja sababu mbili za Ukawa kumkaribisha Lowassa kuwa mgombea urais wakati chama hicho kilimtaja katika orodha ya mafisadi mwaka 2007. “Edward Lowassa ni mwanasiasa asiyeeleweka na aliyewagawa watu zaidi kwa sasa katika siasa nchini na amekuwa hivyo kwa muda mrefu. Sisi Chadema tulimweka kwenye orodha ya mafisadi kutokana na kuhusika kwake na kashfa ya Richmond mwaka 2007. Kwa hiyo swali halali kabisa ambalo lazima tulijibu kwa ufasaha ni hili: ‘Kwa nini tumemkubali, siyo tu kumpokea kama mwanachama, bali kumpa heshima ya kuwa mgombea wetu wa urais? Na kwa nini washirika wetu wa Ukawa nao wamemkubali kuwa mgombea wao wa urais? “Jibu ni kwamba tupo katika kipindi na mazingira ya kipekee ya kisiasa katika nchi yetu. Kwa mara ya kwanza katika historia yetu kama Taifa, tunaona mfumo tawala ukipasuka vipandevipande. Kwa mara ya kwanza tunaona CCM ikipasuka katikati, na mtu aliyeipasua CCM na mfumo tawala ni Edward Lowassa. “Sisi Chadema tumefanya kazi kubwa ya kujenga chama tangu 2010. Tuna wagombea wengi na bora katika majimbo mengi ya uchaguzi na ngazi ya madiwani kuliko ambavyo tumewahi kuwa nao kwa miaka yote ya nyuma. “Hata hivyo, ni ukweli pia kwamba kuna maeneo mengi ya nchi ambako tuko dhaifu sana. Kwa kuingia kwake Chadema na Ukawa, Lowassa anayaingiza maeneo hayo kwenye ulingo wa kisiasa na sisi kuyafikia. “Na Lowassa ataiporomosha CCM kwa sababu ana nguvu kubwa ndani ya chama hicho kuliko mwanasiasa mwingine yeyote. Katika mazingira ya sasa ya kipekee, tunahitaji kuamua nani ni adui mkubwa zaidi wa nchi yetu na ustawi wake; Edward Lowassa mtuhumiwa wa ufisadi au CCM na mfumo tawala ambao unajenga mazingira yanayostawisha na kulinda ufisadi? “Sisi Chadema na Ukawa tumeamua kuwa adui yetu mkubwa wa sasa na siku zote ni CCM na mfumo tawala. Tumemkaribisha Edward Lowassa kwa sababu kuwapo kwake kutaharakisha kuiangamiza CCM na mfumo tawala. Tunaomba wananchi mtuelewe na kutuunga mkono? Kwa nini Dk Slaa hakuonekana Katika mkutano wa kumtambulisha Lowassa, baadhi ya viongozi waandamizi wa Chadema hawakuhudhuria, kitendo kilichofafanuliwa jana kuwa walikuwa na majukumu mengine kichama. Naibu Katibu Mkuu wa Chadema (Zanzibar), Salum Mwalimu alisema taarifa zinazosambazwa katika mitandao ya kijamii kwamba viongozi hao wamechukizwa na uamuzi wa chama hicho kumkubali Lowassa ajiunge Chadema, si za kweli. Viongozi ambao hawakuonekana katika mkutano huo uliofanyika katika Hoteli ya Ledger Bahari Beach ni Katibu Mkuu wa Chadema, Dk Willibrod Slaa, Naibu wake (Bara), John Mnyika na Mwanasheria Mkuu wa chama hicho, Tundu Lissu. “Kama mnavyojua kwa sasa kuna mambo mengi yanaendelea nchini likiwamo suala la uandikishaji wa wananchi katika daftari la wapigakura,” alisema Mwalimu huku akifafanua kuwa mchakato huo ni moja ya mambo yanayofuatiliwa kwa ukaribu na viongozi wa Chadema. “Mbona suala hili mnataka kulikuza sana. Ni kitu cha kawaida Chadema ni chama kikubwa na viongozi wake wana shughuli nyingi za kufanya,” alisisitiza. “Jana, (juzi) Dk Slaa hakuwapo wala Lissu, lakini katika mkutano wa leo (jana) Lissu kaja Dk Slaa hajaja. Na hata leo (jana) Mbowe ambaye tulikuwa naye jana leo hayupo. Kwa hiyo ni suala la utaratibu tu na si kila tukio lazima tuwe wote,” alisema. Kuchukua fomu Katika hatua nyingine, Mwalimu alisema leo Lowassa atachukua fomu za kuomba ridhaa ya kuwania urais kupitia Chadema katika ofisi za makao makuu ya chama hicho, Kinondoni, Dar es Salaam. “Atachukua fomu kesho (leo) na kutakuwa na shamrashamra za aina yake,” alisema. Kingunge, Sophia wajitenga Mwanasiasa mkongwe nchini, Kingunge Ngombale Mwiru na Waziri wa Maendeleo ya Wanawake, Jinsia na Watoto, Sophia Simba wametoa kauli zinazoashiria kujitenga na uamuzi wa Lowassa kuondoka CCM. Simba, ambaye pia ni Mwenyekiti wa Umoja wa Wanawake wa CCM (UWT), alisema bado ni mwanachama wa CCM na kuwa uamuzi wa Lowassa ni wa mtu binafsi. “Mimi haunihusu, bado ni mwanachama wa CCM, tafadhali msinisumbue,” alisema. Simba, pamoja na wajumbe wenzake wa Kamati Kuu ya CCM; Mbunge wa Songea Mjini (CCM), Dk Emmanuel Nchimbi na Adam Kimbisa waliitisha mkutano wa waandishi wa habari kuipinga kamati hiyo kwa kulikata jina la Lowassa katika mchakato wa kumpata mgombea wa urais. Aidha, Kingunge ambaye wakati wa kusaka wadhamini katika mchakato wa awali wa urais ndani ya CCM alijitokeza hadharani kumuunga mkono Lowassa alisema hatua yake ya Mbunge huyo wa Monduli kuhamia Chadema ni uamuzi binafsi hivyo hawezi kuutolea maoni yoyote. “Kama ameondoka, basi anatakiwa aulizwe yeye na wala si mimi kwa sababu kila mtu ana maamuzi yake binafsi,” alisema.

[via LEKULE]

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Bosi mpya NMG: Nitasimamia weledi na uhuru wa habari

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Ofisa Mtendaji Mkuu wa Kampuni ya Nation Media Group (NMG), Joe Muganda akizungumza na mwakilishi Mkazi wa Aga Khan Development Network (AKDN), Amin Kurji (Kulia) , pamoja na mjumbe wa Bodi ya Wakurugenzi ya Kampuni ya Mwananchi Communications Limited (MCL) Hanif Jaffer na  mwenyekiti wa Bodi ya MCL Leonard Mususa( wa pili kushoto), wakati wa hafla ya kumkaribisha iliyofanyika kwenye Hotel ya Serena, jijini  Dar es Salaam juzi. Picha na Emmanuel Herman Dar es Salaam . Ofisa Mtendaji Mkuu mpya wa kampuni ya habari ya Nation Media Group (NMG), Joe Muganda ameahidi kusimamia kikamilifu weledi na uhuru wa vyombo vya habari vya kampuni hiyo, ambavyo ni pamoja na magazeti ya The Citizen, Mwananchi na Mwanaspoti yanayozalishwa na Mwananchi Communication Limited. Muganda alisema hayo wakati akitambulishwa kwa wafanyakazi wa Mwananchi Communications Limited na wadau wa habari. Mwananchi Communication Limited ya Tanzania na The Monitor ya Uganda ni kampuni tanzu za NMG. Muganda, aliyeanza kazi na NMG takriban mwezi mmoja uliopita akichukua nafasi ya Linus Gitahi, alisema kwa kipindi chote cha mkataba wake anapenda kuongoza kampuni ambayo habari zake zinaaminika na kila mtu na kufanya kazi kwa uhuru wa hali ya juu. Muganda aliwaeleza wadau waliohudhuria hafla ya utambulisho huo jijini hapa juzi kuwa wakati huu wa uchaguzi, MCL haitafungamana na upande wowote na itaendelea kutoa habari kwa uwajibikaji mkubwa. “Uwajibikaji ni jambo la msingi sana unapoongoza chombo cha habari kwa sababu iwapo ukikosea kidogo unaweza kulipeleka taifa katika uelekeo mbaya,” alisema Muganda. “Lazima tuhakikishe habari ni ya kweli, inatenda haki kwa wote na kubwa zaidi ni kuwa huru… hiyo misingi ndiyo nitakayoisimamia kikamilifu,” alisema Muganda. Ahadi hiyo aliirudia tena jana asubuhi wakati akitambulishwa kwa wa wafanyakazi wa MCL kuwa wakati huu wa uchaguzi, kampuni haitaegemea upande wowote hivyo uwajibikaji huo na weledi utasaidia vyombo vyote vya kampuni hiyo kuaminika kwa wadau wake. “Hatutakiwi tuwe na tofauti na mamlaka. Tunachotaka ni kuwa huru kwa kila kitu tunachokifanya na siyo kuambiwa nini tufanye… tutakuwa wazi, watenda haki kwa kila mtu,” alisema Muganda huku akiwasihi wafanyakazi hao kufanya kazi kwa bidii ili kutimiza malengo ya kampuni. Katika hafla ya juzi iliyohudhuriwa na wanahisa, wasomaji, watangazaji, wafanyakazi wa MCL na wajumbe wa Bodi ya Wakurugenzi, Muganda alisema atajikita katika kuhakikisha anafanikisha matarajio ya wanahisa wa kampuni hiyo. Alisema ataweka mkazo katika kukuza vipaji vya vijana watakaosaidia kusukuma gurudumu la maendeleo ya nchi na bara la Afrika kwa ujumla. “Mara nyingi sana tumekuwa hatutilii maanani uendelezaji wa mtaji wa nguvu kazi imara na yenye uweledi wa kutosha. Katika uongozi wangu nitafanya kila niwezalo kuendeleza vipaji na nguvu kazi kwa kuwashirikisha Watanzania kikamilifu,” alisema Muganda. Akizungumza kwenye hafla hiyo, mwenyekiti wa Bodi ya Wakurugenzi wa MCL, Leonard Mususa aliipongeza kampuni hiyo kwa kazi kubwa inayoifanya katika kuandika habari za Uchaguzi Mkuu kwa kina na haraka hasa wakati wa mchakato wa kumpata mgombea wa urais CCM. Alisema wakati wa kutafuta tano bora hadi anavyolala hakuwa amepata habari yoyote ya matokeo, lakini alivyoamka asubuhi alikuta magazeti ya MCL yameandika kiundani habari hiyo. Mususa hakusita kuendeleza na kilio cha kuiomba Serikali iliruhusu gazeti la The East African lianze tena kusambazwa nchini baada ya Serikali kulifungia Januari mwaka huu. Mususa alisema soko la habari lina changomoto lukuki ambazo zinafahamika bayana na wadau wake. “Hadi sasa tunavyozungumza gazeti lililokuwa linapendwa nchini la The East African bado limefungiwa. Tunaamini kuwa Serikali italifungulia ili lianze kusambazwa tena nchini,” alisema. “Nimeongea na wadau mbalimbali juu ya hilo na hata viongozi waliopo serikalini wanalipenda The East African…kwa chochote kilichotokea kisiwe tena sababu bali tunatakiwa kuyamaliza na kuwarudishia wasomaji gazeti walipendalo.” Alisema kuna dalili za wazi kuwa hakuna kuaminiana kati ya vyombo habari na Serikali hivyo tasnia ya habari inatakiwa kujenga uaminifu na uhusiano mzuri na mamlaka kwa kuandika habari za kweli, haki na zisizoegemea upande wowote. Mususa alisema MCL inataka kuongeza kiwango cha tabia ya kujisomea kwa kuwaomba wadau kutoa maoni juu ya masuala wanayopenda kuyasoma ili yaweze kuandikwa kwa ubora na uweledi wa hali ya juu. Mkurugenzi Mtendaji wa MCL, Francis Nanai alimuelezea Muganda kuwa ni “kiongozi mzuri ambaye tutanya naye kazi vizuri kama yule aliyetoka (Gitahi)”.

[via LEKULE]

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Naibu Spika adaiwa kumpiga mgombea CCM

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Dodoma. Kampeni za wagombea ubunge wa Jimbo la Kongwa juzi zilikumbwa na tafrani baada ya Naibu Spika wa Bunge, Job Ndugai kudaiwa kumchapa fimbo na baadaye kumpiga ngumi mgombea mwenzake aliyeanguka na kuzirai. Mgombea huyo, Dk Joseph Chilongani, ambaye hivi sasa amelazwa Hospitali ya Wilaya ya Kongwa, alipata kipigo hicho juzi saa 10.20 jioni wakati walipokuwa kwenye mkutano wa kampeni uliofanyika Kata ya Ugogoni wilayani Kongwa. Kwa kawaida, wagombea ubunge wa CCM hupelekwa pamoja na chama hicho kwenye mikutano ya kampeni ya kila kata ambako hujieleza kwa wanachama kabla ya siku ya kupigiwa kura. Mpambe wa Dk Chilongani, Shaaban Chihimba alimwambia mwandishi wetu kuwa Ndugai alimshambulia mpinzani wake kutokana na kukasirika baada ya mgombea mwingine, Simon Katunga kujinadi kwa kuponda utendaji wa mbunge wa sasa wa Kongwa. “Mgombea huyo alisema fedha zinazochangwa na wananchi kwa ajili ya miradi ya maendeleo katika halmashauri yetu zimekuwa zikiliwa hivyo akichaguliwa atahakikisha fedha hizo zinatumika kwa mambo yaliyokusudiwa,” alidai Chihimba.  Alisema kuwa kauli hiyo ilionekana kumkera  Ndugai, hali iliyomfanya kusimama na kutaka kwenda kumpiga mgombea huyo, lakini viongozi wa CCM walimzuia.  “Akiwa anataka kuketi, alimuona Dk Chilongali akirekodi tukio hilo kwa kutumia simu ya mkononi, ndipo alipomwendea na kumpiga ngumi za usoni na fimbo kwenye tumbo hali iliyosababisha kuanguka chini na kuzirai,” alidai. Video ambayo imesambaa kwenye mitandao ya kijamii, inamuonyesha Ndugai akiwa ameshikilia fimbo mkononi huku akisema “embu na wewe usinipige, unanipiga makamera ya nini?” Chihimba alidai kuwa baada ya mgombea huyo kuanguka, mkutano huo ulivurugika na wagombea wengine wakishirikiana na baadhi ya wanachama walimchukua Dk Chilongani na kumpeleka kabla ya kupelekwa hospitali. Kamanda wa Polisi Mkoa wa Dodoma, David Misime, alisema jana jioni kuwa Dk Chilongani alifika Kituo cha Polisi Kongwa na kutoa taarifa za kushambuliwa kichwani na tumboni kwa fimbo. “Uchunguzi wa tukio hilo unaendelea kwa kuwahoji watu waliokuwapo na mara baada ya upelelezi kukamilika jalada litapelekwa kwa wakili wa Serikali kwa ajili ya utekelezaji wa hatua stahiki za kisheria,” alisema. Alipoulizwa kuhusu tukio hilo, Ndugai alijibu kupitia ujumbe mfupi wa simu akisema: “Ni kweli kumetokea mtafaruku, lakini hakuna aliyepigwa ngumi. Na katika maisha yangu sijawahi kumpiga mtu ngumi.” Mganga mkuu wa Wilaya ya Kongwa, Dk Festo Mapunda alikiri kupokewa kwa mgombea huyo juzi jioni lakini alikataa kuzungumza zaidi. Kaimu Katibu wa CCM Wilaya ya Kongwa, Peter Minja alikiri kutokea kwa tukio hilo lakini akasema si kwa ukubwa huo. “Leo asubuhi (jana), tutakuwa na kikao cha kulijadili na baadaye tutatoa taarifa… tunaendelea na kampeni,” alisema Minja. Hata hivyo, Minja alikataa kuthibitisha iwapo ni kweli mgombea huyo alipigwa au kukanusha kwa madai kuwa hakuwepo eneo la tukio. “Tulishamuita mgombea huyo na kumuonya kuhusu kujinadi kwa kukipaka matope chama na halmashauri kwa sababu Halmashauri ya Kongwa imepata cheti safi cha (Mkaguzi na Mdhibiti Mkuu wa Hesabu za Serikali – CAG), lakini hakusikia aliendelea. “Tumepata taarifa ya maneno, lakini tunasubiri ya maandishi, taarifa ya polisi na hospitali kwa kuwa utaratibu wa chama unasema kila mwenye malalamiko awasilishe katika vikao husika.” Minja alisema alikwenda jana hospitalini kumuona mgonjwa huyo, lakini hakuweza kuzungumza naye. Hata hivyo, alisema jana polisi waliwahoji baadhi ya viongozi, wanachama na wagombea kuhusu tukio hilo. Alisema tukio hilo limesababisha mchakato wa kampeni za kura za maoni kusimama hadi leo. “Tulikuwa tumebakiza kata mbili za Sejeli na Kongwa Mjini ambazo zimesalia kwa watia nia kupiga kampeni na hizi tutamalizia kesho,” alisema.

[via LEKULE]

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CCM Dar yaikaba koo Tume ya Uchaguzi

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Dar es Salaam. Chama cha Mapinduzi (CCM) Mkoa wa Dar es Salaam kimeitaka Tume ya Taifa ya Uchaguzi (NEC) kusimamia kwa makini uandikishaji wapigakura jijini hapa ili wakazi wote wapate fursa ya kuandikishwa, ndani ya muda uliopangwa. Katibu wa Siasa, Itikadi na Uenezi wa CCM Mkoa wa Dar es Salaam, Juma Simba aliwaambia wanahabari jana kuwa ufanisi katika uandikishaji utasaidia kumaliza idadi kubwa ya wakazi ambao bado hawajaandikishwa hadi sasa. “NEC inatakiwa kuwa makini kukamilisha uandikishaji kwa kuongeza mashine na watendaji ili wakazi wengi wa Dar es Salaam waandikishwe,” alisema. Kuhusu Lowassa Simba alisema CCM haitatetereka na uamuzi wa Waziri Mkuu wa zamani, Edward Lowassa kuhamia Chadema. Alisema uamuzi huo siyo wa kwanza, kwani Augustine Mrema aliwahi kuondoka CCM na kujiunga na upinzani. Kauli ya kiongozi huyo imekuja siku moja tangu Lowassa na mkewe, Regina, waihame CCM na kujiunga na Chadema na kuahidi kuendelea na safari ya matumaini ndani ya Umoja wa Katiba ya Wananchi (Ukawa). “Lowassa alijiunga CCM kwa ridhaa yake, hakuna aliyemshurutisha na ametoka kwa ridhaa yake kwenda Chadema hakuna aliyemshurutisha. “CCM itabaki kuwa CCM zaidi ya hilo, lipi jipya?” Simba alisema tishio kwamba Lowassa ataondoka na makada wengi wa chama hicho ni propaganda za kupuuzwa. Jaji Lubuva alonga Akizungumza na mwandishi wetu jana, Mwenyekiti wa NEC, Jaji mstaafu Damian Lubuva alisema muda wa kuandikisha wapigakura utaongezwa baada ya kujua idadi ya watakaosalia ifikapo mwisho wa kujiandikisha Agosti 31. “Kwa sasa hatuwezi kusema tutaongeza siku ngapi, lakini ikifika siku ya mwisho tutajua watu wangapi wamebaki na hapo ndipo tutaongeza muda au la,” alisema Lubuva. Alisema utaratibu wa kuanza uandikishaji kuanzia saa moja asubuhi hadi 12 jioni, unaweza kuongeza kasi ya uandikishaji na hivyo watakaosalia watapewa muda kulingana na idadi yao. Waandikishaji wakaidi agizo la NEC Licha ya NEC kutoa agizo kwa mawakala wa BVR kuanza kufungua vituo kuanzia saa moja asubuhi, badala ya saa mbili, baadhi ya mawakala katika vituo wamekaidi agizo hilo. Jaji Lubuva alitoa agizo hilo juzi akiwataka mawakala hao kufungua vituo muda huo lengo likiwa kuhakikisha idadi kubwa ya watu wanaandikishwa. Hata hivyo, agizo hilo lilionekana kupuuzwa na mawakala wa baadhi ya vituo ambao walifungua vituo hivyo kati ya saa mbili na saa tatu asubuhi. Waandishi wetu walipita katika baadhi ya vituo na kukuta watu wakilalamikia suala hilo. Mmoja wa wananchi waliokuwa kwenye Kituo cha Shule ya Msingi Mivinjeni, Lekule Mollel alisema walifika kituoni hapo mapema, lakini kilifunguliwa saa tatu asubuhi na siyo saa moja kama inavyotakiwa. Wakala wa kituo hicho, Malick Shaaban alikiri kuchelewa kufunguliwa kwa kituo hicho na kudai kuwa baadhi ya mawakala wanaishi mbali na eneo hilo. Katika vituo vya Tabata, Temeke na Mbagala wananchi pia wamelalamik baadhi ya vituo kuchelewewa kufunguliwa tofauti na agizo. Mkazi wa Tabata, aliyekuwa akijiandikisha kwenye Kituo cha Shule ya Sekondari Ari B, Tabata Kinyerezi, Elizabeth Mwijage alisema baadhi ya mawakala wa kituo hicho walipoulizwa juu ya hilo walidai hawakuwa na taarifa. Licha ya kwamba walifungua saa moja, lakini uandikishaji ulianza saa tatu asubuhi kutokana na matatizo ya mashine kugoma kabla ya kuanza kazi. “Tumefika hapa saa kumi na moja alfajiri tulivyoona wamewahi kufungua kituo tulifurahi tukijua uandikishaji utaanza mapema, lakini mashine zilichukua muda ilipofika saa tatu ndiyo mtu wa kwanza alianza kuandikishwa,” alisema Juma Pascal aliyekuwa Kituo cha Serikali ya Mtaa Kibondemaji B.

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‘Lipumba alikaidi amri ya polisi’

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Dar es Salaam. Kamishna Msaidizi wa Polisi, Sebastian Zacharia ameieleza Mahakama ya Hakimu Mkazi Kisutu kuwa alimuomba Mwenyekiti wa Chama cha Wananchi (CUF), Ibrahim Lipumba atii amri ya polisi ya kuzuia maandamano yao lakini alikaidi. Zacharia ambaye alikuwa Kaimu Kamanda wa Polisi Mkoa wa Temeke na kuhamishiwa Makao Makuu Kitengo cha Upelelezi, alisema hayo jana mbele ya Hakimu Mfawidhi, Cyprian Mkeha. Akitoa ushahidi, Zacharia alidai kuwa Januari 26, mwaka huu waliona tangazo la CUF kufanya maandamano na mkutano Januari 27, Mbagala Zakhem kupitia runinga ndipo alipowatuma watu wake wafuatilie kama kuna ukweli. Alidai kuwa Januari 27, mwaka huu katika Mtaa wa Boko Temeke eneo hilo kipolisi lilikuwa chini yake. “Sikuwa na taarifa ya maandishi niliwasiliana na Kamanda Simon Siro na kumwambia taarifa hizo za CUF kufanya maandamano na mkutano wanazo lakini wameyazuia na akaniletea nakala ya zuio hilo. “Niliwaita maofisa wa polisi na kuwaonyesha nakala ya zuio, kisha nikataka wakae tayari kwa lolote litakalojitokeza. Siku hiyo tulisubiri ili kuona kama kuna dalili zozote za maandamano, ilipofika saa saba mchana SP Msuya alinipigia simu na kunijulisha kuwa wameanza kukusanyika na Lipumba alikuwapo. “Nikawataka waendelee kungalia kama wana dalili za kuondoka kwa maandamano,” alieleza Zacharia. Alidai kuwa wafuasi wa Lipumba waliendelea kuongezeka huku wengine wakiwa wameshika vipeperushi vya bendera za CUF na mabango. “Baada ya nusu saa, Lipumba na wafuasi wake walianza kutoka Mtaa wa Boko na kuelekea Barabara ya Sudan hatimaye Mtongani… lilikuwa kundi la watu takribani 200,” alisimulia na kuongeza: “Niliwasihi wasifanye maandamano, watii zuio la polisi na kama hawajaridhika wakate rufaa kwa Waziri wa Mambo ya Ndani, lakini alikaidi.” Alidai kuwa Lipumba alikiri kupokea barua ya polisi ya zuio, lakini alimueleza kuwa kwa kuwa wamekwisha yaandaa wanaandamana. Zacharia alidai kuwa alimsihi Lipumba tena atii katazo hilo la polisi hakufanya hivyo badala yake wafuasi wake waliwatukana polisi kuwa ni vibaraka wa Chama cha Mapinduzi (CCM). “Hata hivyo, walianza kuondoka na magari yao huku wafuasi wake waliyazunguka kwa mwendo wa mchakamchaka huku wakiwa wamebeba vipeperushi vya bendera za CUF na mabango kuelekea Mbagala Zakhem. “Pia kulikuwapo na kelele, matusi huku watu wengine wakiendelea na shughuli zao hospitalini na benki ya NMB. Polisi tuliona siyo busara kwakuwa mazingira hayo ni hatarishi tukaenda eneo la Mtoni Mtongani kuwasubiri. Walipofika katika eneo hilo walikuja, walipofika tulimuomba tena Lipumba ayasitishe maandamano, akasema anaenda kuongea na wananchi wake wanamsubiri Mbagala Zakhem. “Tulitoa ilani mara tatu ili watawanyike baada ya muda tuliwakama watu 32. Polisi walitumia nguvu ya kawaida na tuliwapeleka kituo cha Kati,” alidai Zacharia. Kesi hiyo itaendelea kusikilizwa leo.

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Nembo ya TBS inawanyanyua wajasiriamali wadogo nchini?

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Hamasa imekuwa ikitolewa kwa walaji kutumia bidhaa ambazo zina nembo ya ubora ya Shirika la Viwango Tanzania (TBS) ili kuepuka kutumia vitu vya kughushi, kama vinavyojulikana kwa wengi; feki. Hali hii imekuwa ikiyafanya kampuni nyingi kubwa kuhakikisha wanafikia viwango ambavyo watatumia nembo hiyo ili bidhaa zao zisitiliwe shaka na watumiaji. Hii ni fursa wanayoipata wafanyabiashara wakubwa. Hata hivyo, Tanzania ni nchi ambayo inapaswa kujenga mazingira mazuri kwa ustawi wa viwanda vidogo na vya kati. Huu ni mfumo unaoweza kuifanya Tanzania kupiga hatua katika mapinduzi ya viwanda. Lakini swali, ni je, hawa wafanyabiashara wadogo wanaotaka kustawi, wanaweza kutumia nembo ya TBS? Ofisa Masoko wa TBS, Gladness Kaseka anasema wana kanuni ambazo pia zinawapa haki wajasiriamali wadogo kutumia nembo hiyo tena bila malipo, tofauti na ilivyo kwa viwanda vikubwa. Kaseka anasema hii ni fursa ya kipekee kwa wajasiriamali kuchangamkia fursa hiyo ya kuruhusiwa kutumia nembo ya ubora ya TBS bila kulipilia. Anasema Serikali hutenga fedha kila mwaka kwa ajili ya kuhudumia wajasiriamali wadogo na wa kati pale wanapoomba bidhaa zao wanazozizalisha wenyewe zithibitishwe kwa ubora. Lengo la kupewa bila malipo, anasema ni kuwapa fursa ya kujitanua na kukua zaidi na hasa ikizingatiwa mitaji yao bado ni midogo na wengi wanarejesha fedha walizokopa kwenye taasisi za fedha. “Hadi hivi sasa wajasiriamali wadogo na wa kati karibu 200, wameomba na kupatiwa alama ya TBS,” anasema Kaseka. Anawataja wajasiriamali wadogo ambao tayari wamepewa vibali vya kutumia nembo hiyo kuwa ni wauza maziwa, asali, unga wa lishe na mafuta ya alizeti. Anasema lengo ni kumhakikishia mlaji kuwa bidhaa ya mjasirimali huyo ina ubora na imethibitishwa na TBS. Pamoja na hali hiyo, anasema TBS inahakikisha mjasiriamali ametekeleza kanuni zote zinazolingana na aina ya biashara anayoifanya. “Kwa wale wajasiriamali wa vyakula wanatakiwa wawe na taarifa fupi kutoka idara ya afya iliyo karibu na mahali pa uzalishaji au cheti cha Mamlaka ya Chakula na Dawa (TFDA),” anasema Kaseka akifafanua: “Ni vyema kuhakikisha kuwa barua inafafanua vizuri na kwa kina shughuli zinazofanywa na mjasiriamali huyo,” anasema Kaseka. Ofisa Viwango wa Chakula na Kilimo wa TBS, Zena Issa anasema wajasiriamali waliokwishapata leseni ya kutumia alama ya ubora wanapaswa kutunza taarifa za uzalishaji na mauzo ambazo wanatakiwa kuzionyesha kwa wakaguzi wa Shirika la Viwango. Anasema alama ya ubora huthibitisha kuwa bidhaa husika inafaa kwa matumizi husika, huongeza ubora wa bidhaa, huongeza wateja zaidi, hulinda mazingira ya eneo husika na kumhakikishia mlaji usalama wake wa kiafya katika matumizi. “Alama ya ubora wa TBS huwafanya wanunuzi kununua bidhaa bila wasiwasi. Kwa upande mwingine alama hiyo humlinda mzalishaji katika ushindani dhidi ya bidhaa hafifu na humwezesha kulihakikishia soko lake katika kiwango na hivyo ni bora na salama kwa matumizi yaliyokusudiwa,” anasema Issa. Mjasiriamali wa kuuza maziwa katika mtaa wa Negamsii wilayani Babati Mkoani Manyara, Magreth Tluway anasema mteja anaponunua bidhaa anapaswa kuangalia endapo ina alama ya uthibitisho wa ubora. Mjasiriamali wa kuuza asali, John Aloyce, mkazi wa mtaa wa Nangara, anasema kupitia nembo ya TBS, ameongeza idadi ya wateja wananunua bidhaa. “Napenda kutoa wito kwa wajasiriamali wenzangu wadogo na wa kati, waliopo Manyara na mikoa mingine, tujitokeze kwa wingi kwa ajili ya kupata fursa hii kwani itatusaidia katika kutuongezea soko la bidhaa zetu,” anasema Aloyce. Wajasiriamali waliofanikiwa kutumia nembo ya TBS wanaonyesha kuwa bidhaa zao zinakubalika, hivyo ni moja ya njia za kuwainua kibiashara. Jambo muhimu ni kwamba nembo hiyo pia inapaswa kuwachochea wajasiriamali hawa kuongeza juhudi za kutengeneza bidhaa bora ambazo zitashindana na zile za viwanda vikubwa.

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Michezo Ya Olympic 2016 Yaingia Kasoro

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Rais wa Kamati kuu ya Kimataifa ya Olimpiki, Thomas Bach, amesema kuwa uchafuzi wa bahari ni moja ya kikwazo Rio de Janeiro katika maandalizi ya michuano ya hapo mwakani. Hata hivyo kutokana na hali hiyo waandaji wa mashindano hayo ya riadha wamesema kuwa watafanya kila linalowezekana kwa afya ya wanariadha wakati wa Olympiki. Takribani asilimia 70 ya maji taka yanamwagika Rio de Janeiro katika fukwe za Guanabara,eneo ambalo wapiga mbizi watafanyia mashindano yao. Katika hali inayoonyesha ni hatari kwa afya wanariadha walioko kwenye mafunzo katika pwani hiyo wameona mizoga ya wanyama na uchafu ukiwa ukingoni mwa eneo hilo ambalo mashindano hayo yatafanyika.

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Mwana Wa Mfalme Ampinga Platini

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Aliyekua mgombea nafasi ya urais wa shirikisho la soka duniani FIFA, Ali bin Al Hussein amempinga rais wa shirikisho la soka barani Ulaya UEFA, Michel Platini kwa kusema hafai kusimama katika kinyang’anyiro cha kujaza nafasi ya Sepp Blatter kwenye uchaguzi wa mwezi februari mwakani. Ali bin Al Hussein ambaye ni mtoto wa mfalme wa Jordan, ametoa angalizo hilo baada ya saa 24 kupita, ambazo zilishuhudia Platini akitangaza nia ya kuwania kiti cha uraisi wa FIFA baada ya kupata Baraka kutoka kwa wajumbe wa kamati ya utendaji ya UEFA mwishoni mwa juma lililopita. Al Hussein amesema Platini hana sifa zilizo thabit za kuiongoza FIFA ambayo kwa sasa imetapakaa uchafu wa rushwa, hivyo amewataka wadau wa soka duniani kutambua kwamba kuna ulazima kwa baadhi ya viongozi kujipima kabla ya kutangaza nia ya kuwania nafasi kubwa katika taasisi za kidunia. Hata hivyo Al Hussein hakuweka wazi ni vipi Platini hatoshi katika nafasi hiyo kwa vigezo vya kuzuia rushwa, zaidi ya kusisitiza kuna ulazima kwa baadhi ya watu kujichunguza kwanza kutokana na vitendo vinavyoendelea miongoni mwa watu wanaowazunguuka. Katika hatua nyingine Al Hussein, bado hajatangaza kama atawania nafasi ya urais kwa mara nyingine tena ama la, hali ambayo inahisiwa huenda ikawa ni hofu kwake baada ya kuona Platini ametangaza nia ya kukitaka kiti cha urais wa FIFA.

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Maradona Amtuhumu Mtalaka Wake

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Nguli wa soka Duniani ,Diego Maradona amemtuhumu mke wake wa zamani Claudia Villafañe kwamba kumuibia kiasi cha fedha zipatazo dola milioni tisa, katika akaunti yake ya benki. Akizungumza katika matangazo ya moja kwa moja ya Luninga,Maradonna amesema Villafañe ambaye alikuwa mpenzi wake wa zamani ni mwizi. Hata hivyo Villafañe amepinga vikali madai na kudai kuwa yeye si mwizi na hakuiba fedha hizo. Wapenzi hao ambao walikutana katika mji uliokithiri kwa umasikini huko Buenos Aires kabla ya Maradonna kuwa maarufu na kuwa miongoni mwa wachezaji mahiri duniani katika historia ya soka,waliachana kimapenzi kutokana na kutofautiana. Watoto wao wawili Dalma and Giannina,wamekaririwa kwenye mtandao wa twitter wakimtetea mama yao wazi wazi na kwamba hahusiki na upotevu huo wa fedha za baba yao.

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Aunt azua minong’ono ukumbini usiku

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STAA wa kiwango cha juu kupitia filamu za Kibongo, Aunt Ezekiel Grayson, kwa mara ya kwanza tangu ajifungue, amezua minong’ono ukumbini. Mpango mzima ulishuhudiwa usiku kwenye Ukumbi wa Ngome Kongwe, Zanzibar ambapo kulikuwa na Tamasha la Kimataifa la Filamu (ZIFF) ambapo Aunt alitinga akiwa na baadhi ya mastaa wenzake huku baadhi ya watu wakishangaa na kunong’ona kuwa mtoto wake bado ni mdogo iweje awe ukumbini  badala ya kuwa naye muda huo. “Mmmmh huyu siyo Aunt kweli? Jamani mtoto wake mbona bado mdogo sana kwa nini amekuja ukumbini usiku wote huu?” alihoji mmoja wa watu waliokuwa ukumbini humo. mtandao huu u lipozungumza na Aunt kuhusiana na minong’ono hiyo alisema: “Niko makini san-a kwa upande wa mtoto, hapa nilipo nikitoka nje tu naona hoteli niliyofikia na mwanangu hivyo hakuna shida na siwezi kuja na mtoto hapa kwenye mkusanyiko wa watu wengi,” alisema Aunt.

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Electromagnetic Relay Working,Types of Electromagnetic Relays

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 Electromagnetic Relay Electromagnetic relays are those relays which are operated by electromagnetic action. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. It will take much longer time to be replaced the all electromagnetic relays by micro processor based static relays. So before going through detail of protection relay system we should review the various types of electromagnetic relays .  Electromagnetic Relay Working Practically all the relaying device are based on either one or more of the following types of electromagnetic relays . Magnitude measurement, Comparison, Ratio measurement. Principle of electromagnetic relay working is on some basic principles. Depending upon working principle the these can be divided into following types of electromagnetic relays . Attracted Armature type relay, Induction Disc type relay, Induction Cup type relay, Balanced Beam type relay, Moving coil type relay, Polarized Moving Iron type relay. Attraction Armature Type Relay Attraction armature type relay is the most simple in construction as well as its working principle. These types of electromagnetic relays can be utilized as either magnitude relay or ratio relay. These relays are employed as auxiliary relay, control relay, over current, under current, over voltage, under voltage and impedance measuring relays. Hinged armature and plunger type constructions are most commonly used for these types of electromagnetic relays. Among these two constructional design, hinged armature type is more commonly used. We know that force exerted on an armature is directly proportional to the square of the magnetic flux in the air gap. If we ignore the effect of saturation, the equation for the force experienced by the armature can be expressed as, Where F is the net force, K’ is constant, I is rms current of armature coil, and K’ is the restraining force. The threshold condition for relay operation would therefore be reached when KI 2 = K’. If we observe the above equation carefully, it would be realized that the relay operation is dependent on the constants K’ and K for a particular value of the coil current. From the above explanation and equation it can be summarized that, the operation of relay is influenced by Ampere – turns developed by the relay operating coil, The size of air gap between the relay core and the armature, Restraining force on the armature. Construction of Attracted Type Relay This relay is essentially a simple electromagnetic coil, and a hinged plunger. Whenever the coil becomes energized the plunger being attracted towards core of the coil. Some NO-NC (Normally Open and Normally Closed) contacts are so arranged mechanically with this plunger, that, NO contacts become closed and NC contacts become open at the end of the plunger movement. Normally attraction armature type relay is dc operated relay. The contacts are so arranged, that, after relay is operated, the contacts cannot return their original positions even after the armature is de energized. After relay operation, this types of electromagnetic relays are reset manually. Attraction armature relay by virtue of their construction and working principle, is instantaneous in operation. Induction Disc Type Relay Induction disc type relay mainly consists of one rotating disc. Induction Disc type Relay Working Every induction disc type relay works on the same well known Ferraries principle . This principle says, a torque is produced by two phase displaced fluxes, which is proportional to the product of their magnitude and phase displacement between them. Mathematically it can be expressed as- The induction disc type relay is based on the same principle as that of an ammeter or a volt meter, or a wattmeter or a watt hour mater. In induction relay the deflecting torque is produced by the eddy currents in an aluminium or copper disc by the flux of an ac electromagnet. Here, an aluminium (or copper) disc is placed between the poles of an AC magnet which produces an alternating flux φ lagging from I by a small angle. As this flux links with the disc, there must be an induced emf E 2 in the disc, lagging behind the flux φ by 90 o . As the disc is purely resistive, the induced current in the disc I 2 will be in phase with E 2 . As the angle between φ and I 2 is 90°, the net torque produced in that case is zero. As, In order to obtain torque in induction disc type relay, it is necessary to produce a rotating field. Pole Shading Method of Producing Torque in Induction Disc Relay In this method half of the pole is surrounded with copper ring as shown. Let φ 1 is the flux of unshaded portion of the pole. Actually total flux divided into two equal portions when the pole is divided into two parts by a slot. As the one portion of the pole is shaded by copper ring. There will be induced current in the shade ring which will produce another flux φ 2 ‘ in the shaded pole. So, resultant flux of shaded pole will be vector sum of & phi; 1 and φ 2 . Say it is φ 2 , and angle between φ 1 and φ 2 is θ. These two fluxes will produce a resultant torque, There are mainly three types of shape of rotating disc are available for induction disc type relay. They are spiral shaped, round and vase shaped, as shown. The spiral shape is done to compensate against varying restraining torque of the control spring which winds up as the disc rotates to close its contacts. For most designs, the disc may rotate by as much as 280°. Further, the moving contact on the disc shift is so positioned that it meets the stationary contacts on the relay frame when the largest radius section of the disc is under the electromagnet. This is done to ensure satisfactory contact pressure in induction disc type relay. Where high speed operation is required, such as in differential protection, the angular travel of the disc is considerably limited and hence circular or even vane types may be used in induction disc type electromagnetic relay. Some time it is required that operation of an induction disc type relay should be done after successful operation of another relay. Such as inter locked over current relays are generally used for generator and bus bar protection. In that case, the shading band is replaced by a shading coil. Two ends of that shading coil are brought out across a normally open contact of other control device or relay. Whenever the latter is operated the normally open contact is closed and makes the shading coil short circuited. Only after that the over current relay disc starts rotating. One can also change the time / current characteristics of an induction disc type relay, by deploying variable resistance arrangement to the shading coil. Induction disc relay fed off a negative sequence filter can also be used as Negative-sequence protection device for alternators. Induction Cup Type Relay Induction cup type relay can be considered as a different version of induction disc type relay. The working principle of both type of relays are more or less some. Induction cup type relay are used where, very high speed operation along with polarizing and/or differential winding is requested. Generally four pole and eight pole design are available. The number of poles depends upon the number of winding to be accommodated. The inertia of cup type design is much lower than that of disc type design. Hence very high speed operation is possible in induction cup type relay. Further, the pole system is designed to give maximum torque per KVA input. In a four pole unit almost all the eddy currents induced in the cup by one pair of poles appear directly under the other pair of poles – so that torque / VA is about three times that of an induction disc with a c-shaped electromagnet. Induction cup type relay is practically suited as directional or phase comparison units. This is because, besides their sensitivity, induction cup relay have steady non vibrating torque and their parasitic torque due to current or voltage alone are small. Induction Cup Type-Directional or Power Relay It in a four pole induction cup type relay, one pair of poles produces flux proportional to voltage and other pair of poles produces flux proportional to current. The vector diagram is given below, The torque T 1 = Kφ vi .φ i .sin(90° − θ) assuming flux produced by the voltage coil will lag 90° behind its voltage. By design, the angle can be made to approach any value and a torque equation T = K.E.I.cos(φ − θ) obtained, where θ is the E – I system angle. Accordingly, induction-cup type relay can be designed to produced maximum torque When system angle θ = 0° or 30° or 45° or 60°. The former is known as power relays as they produce maximum torque when θ = 0° and latter are known as directional relays – they are used for directional discrimination in protective schemes under fault conditions, as they are designed to produce maximum torque at faulty conditions. Reactance or Mho Type Induction Cup Relay By manipulating the current or voltage coil arrangements and the relative phase displacement angle between various fluxes, induction cup type relay can be made to measure pure reactance of a power circuit. Balanced Beam Relay Balanced beam type relay can be said a variant of attraction armature type relay, but still these are treated as different types of relay as they are employed in different field of application. Balanced beam type relays were used in differential and distance protection schemes. The use of these relay becomes absolute as sophisticated induction disc type relay and induction cup type relays supersede them. The working principle of a Balance Beam Relay is quite simple. Here one beam is supported by one hinge. The hinge supports the beam from some where in the middle of the beam. There are two forces acts on two ends of the beams, respectively. The direction of both of the forces are same. Not only direction, in normal working condition the torque produced by the forces in respect of the hinge, are also same. Due to these two same directional torques, the beam is held in horizontal position in normal working condition. One of these torques is restraining torque and other is operating torque. The restraining torque can be provided either by restraining coil or by restraining spring. This is a kind of attracted armature type relay. But balance beam relay is treated separately from their application point of view. When any fault occurred, the current through the operating coil, crosses its pick up value, and hence the mmf of operating coil increases and crosses its pick-up value. Due to this increased mmf, the coil attracts more strongly the beam end and hence, torque on respective end of the beam increases. As this torque is increased, the balance of the beam is being disturbed. Due to this unbalanced torque condition, the beam end associated with operating torque, moves downward, to close No contacts of the relay. Typical arrangement of both types of balance beam relay are illustrated below : Now-a-days, balance beam relays become obsolete. In past these relays were widely used in differential and impedance measurements. The use of these relays are superseded by more sophisticated induction disc and cup type relays. The main drawbacks of balance beam relay, is poor reset / operate ratio, susceptibility to phase displacement between the two energizing and mal-operation on transients. Moving Coil Type Relay The moving coil relay or polarized DC moving coil relay is most sensitive electromagnetic relay. Because of its high sensitive, this relay is used widely for sensitive and accurate measurement for distance and differential protection. This type of relays is inherently suitable for D.C system. Although this type of relay can be used for A.C system also but necessary rectifier circuit should be provided in current transformer. In a moving coil relay the movement of the coil may be rotary or axial. Both of them have been perfected to a large extent by the various manufactures but the inherent limitation of a moving coil relay remains i.e to lead the current in and out of the moving coil system which, far reasons of sensitivity has to be designed to be very delicate. Between these two types of moving coil relay a axial moving type has twice sensitivity than that of rotary type. With moving coil relay, sensitivities of the order of 0.2 mW to 0.5 mW are typical. Speed of operation depends upon damping provided in the relay.

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Transformer Protection and Transformer Fault

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There are different kinds of transformers such as two winding or three winding electrical power transformers, auto transformer, regulating transformers, earthing transformers, rectifier transformers etc. Different transformers demand different schemes of transformer protection depending upon their importance, winding connections, earthing methods and mode of operation etc. It is common practice to provide Buchholz relay protection to all 0.5 MVA and above transformers. While for all small size distribution transformers, only high voltage fuses are used as main protective device. For all larger rated and important distribution transformers, over current protection along with restricted earth fault protection is applied. Differential protection should be provided in the transformers rated above 5 MVA. Depending upon the normal service condition, nature of transformer faults, degree of sustained over load, scheme of tap changing, and many other factors, the suitable transformer protection schemes are chosen. Nature of Transformer Faults Although an electrical power transformer is a static device, but internal stresses arising from abnormal system conditions, must be taken into consideration. A transformer generally suffers from following types of transformer fault- Over current due to overloads and external short circuits, Terminal faults, Winding faults, Incipient faults. All the above mentioned transformer faults cause mechanical and thermal stresses inside the transformer winding and its connecting terminals. Thermal stresses lead to overheating which ultimately affect the insulation system of transformer. Deterioration of insulation leads to winding faults. Some time failure of transformer cooling system, leads to overheating of transformer. So the transformer protection schemes are very much required. The short circuit current of an electrical transformer is normally limited by its reactance and for low reactance, the value of short circuit current may be excessively high. The duration of external short circuits which a transformer can sustain without damage as given in BSS 171:1936. Transformer % reactance Permitted fault duration in seconds 4 % 2 5 % 3 6 % 4 7 % and over 5 The general winding faults in transformer are either earth faults or inter-turns faults. Phase to phase winding faults in a transformer is rare. The phase faults in an electrical transformer may be occurred due to bushing flash over and faults in tap changer equipment. Whatever may be the faults, the transformer must be isolated instantly during fault otherwise major breakdown may occur in the electrical power system. Incipient faults are internal faults which constitute no immediate hazard. But it these faults are over looked and not taken care of, these may lead to major faults. The faults in this group are mainly inter-lamination short circuit due to insulation failure between core lamination, lowering the oil level due to oil leakage, blockage of oil flow paths. All these faults lead to overheating. So transformer protection scheme is required for incipient transformer faults also. The earth fault, very nearer to neutral point of transformer star winding may also be considered as an incipient fault. Influence of winding connections and earthing on earth fault current magnitude. There are mainly two conditions for earth fault current to flow during winding to earth faults, A current exists for the current to flow into and out of the winding. Ampere-turns balance is maintained between the windings. The value of winding earth fault current depends upon position of the fault on the winding, method of winding connection and method of earthing. The star point of the windings may be earthed either solidly or via a resistor. On delta side of the transformer the system is earthed through an earthing transformer. Grounding or earthing transformer provides low impedance path to the zero sequence current and high impedance to the positive and negative sequence currents. Star Winding with Neutral Resistance Earthed In this case the neutral point of the transformer is earthed via a resistor and the value of impedance of it, is much higher than that of winding impedance of the transformer. That means the value of transformer winding impedance is negligible compared to impedance of earthing resistor. The value of earth current is, therefore, proportional to the position of the fault in the winding. As the fault current in the primary winding of the transformer is proportional to the ratio of the short circuited secondary turns to the total turns on the primary winding, the primary fault current will be proportional to the square of the percentage of winding short circuited. The variation of fault current both in the primary and secondary winding is shown below. Star Winding with Neutral Solidly Earthed In this case the earth fault current magnitude is limited solely by the winding impedance and the fault is no longer proportional to the position of the fault. The reason for this non linearity is unbalanced flux linkage.

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Small and Large Motor Protection Scheme

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The electric motor is most essential drive in modern era of industrialization. From fractional hp AC motor used for different home appliances to giant synchronous motor and induction motor of up to 10,000 hp used for different industrial applications, should be protected against different electrical and mechanical faults for serving their purposes smoothly. The motor characteristics must be very carefully considered in selecting the right motor protection scheme. The abnormalities in motor or motor faults may appear due to mainly two reasons – Conditions imposed by the external power supply network, Internal faults, either in the motor or in the driven plant. Unbalanced supply voltages, under-voltage, reversed phase sequence and loss of synchronism (in the case of synchronous motor) come under former category. The later category includes bearing failures, stator winding faults, motor earth faults and overload etc. The degree of motor protection system depends on the costs and applications of the electrical motor. Small Motor Protection Scheme Generally motors up to 30 hp are considered in small category. The small motor protection in this case is arranged by HRC fuse, bimetallic relay and under voltage relay – all assembled into the motor contractor – starter itself. Most common cause of motor burn outs on LV fuse protected system is due to single phasing . This single phasing may remain undetected even if the motors are protected by conventional bimetallic relay. It can not be detected by a set of voltage relays connected across the lines. Since, even when one phase is dead, the motor maintains substantial back emf on its faulty phase terminal and hence voltage across the voltage relay is prevented from dropping – off. The difficulties of detecting single phasing can be overcome by employing a set of three current operated relays as shown in the small motor protection circuit given below. The current operated relays are very simple instantaneous relays. There are mainly two parts in this relay one is a current coil and other is one or more normally open contacts (NO Contacts). The NO contacts are operated by the mmf of the current coil. This relay is connected in series with each phase of the supply and backup by HRC fuse. When the electrical motor starts and runs the supply current passes through the current coil of the protective relay. The mmf of the current coil makes the NO contacts closed. If suddenly a single phasing occurs the corresponding current through the current coil will falls and the contacts of the corresponding relay will become to its normal open position. The NO contacts of the all three relays are connected in series to hold – in the motor contractor. So if any one relay contact opens, results to release of motor contractor and hence motor will stop running. Large Motor Protection Large motor specially induction motors require protection against- Motor bearing failure, Motor over heating, Motor winding failure, Reverse motor rotation. Motor Bearing Failure Ball and roller bearings are used for the motor up to 500 hp and beyond this size sleeve bearings are used. failure of ball or roller bearing usually causes the motor to a standstill very quickly. Due to sudden mechanical jamming in motor bearing, the input current of the motor becomes very high. Current operated protection, attached to the input of the motor can not serve satisfactorily. Since this motor protection system has to be set to override the high motor starting current. The difficulty can be over come by providing thermal over load relay. As the starting current of the motor is high but exists only during starting so for that current the there will be no over heating effect. But over current due mechanical jamming exists for longer time hence there will be a over heating effect. So stalling motor protection can be offered by the thermal overload relay. Stalling protection can also be provided by separate definite time over current relay which is operated only after a certain predefined time if over current persists beyond that period. In the case of sleeve bearing, a temperature sensing device embedded in the bearing itself. This scheme of motor protection is more reliable and sensitive to motor bearing failure since the thermal withstand limit of the motor is quite higher than that of bearing. If we allow the bearing over heating and wait for motor thermal relay to trip, the bearing may be permanently damaged. The temperature sensing device embedded in the bearing stops the motor if the bearing temperature rises beyond its predefined limit. Motor Over Heating The main reason of motor over heating that means over heating of motor winding is due to either of mechanical over loading, reduced supply voltage, unbalanced supply voltage and single phasing. The over heating may cause deterioration of insulation life of motor hence it must be avoided by providing proper motor protection scheme. To avoid over heating, the motor should be isolated in 40 to 50 minutes even in the event of small overloads of the order of 10 %. The protective relay should take into account the detrimental heating effects on the motor rotor due to negative sequence currents in the stator arising out of unbalance in supply voltage. The motor should also be protected by instantaneous motor protection relay against single phasing such as a stall on loss of one phase when running at full load or attempting to start with only two of three phases alive. Motor Winding Failure The motor protection relay should should have instantaneous trip elements to detect motor winding failure such as phase to phase and phase to earth faults. Preferably phase to phase fault unit should be energized from positive phase sequence component of the motor current and another instantaneous unit connected in the residual circuit of the current transformers be used for earth faults protection. Reverse Motor Rotation Specially in the case of conveyor belt, the reverse motor rotation must be avoided. The reverse rotation during starting can be caused due to inadvertent reversing of supply phases. A comprehensive motor protection relay with an instantaneous negative sequence unit will satisfy this requirement. If such relay has not been provided, a watt-meter type relay can be employed. NB: However, we have to provide some additional motor protection system for synchronous motor which is discussed in details in synchronous motor protection topic.  

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Motor Thermal Overload Protection

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Under Electrical Protection For understanding motor thermal overload protection in induction motor we can discuss the operating principle of three phase induction motor. There is one cylindrical stator and a three phase winding is symmetrically distributed in the inner periphery of the stator. Due to such symmetrical distribution, when three phase power supply is applied to the stator winding, a rotating magnetic field is produced. This field rotates at synchronous speed. The rotor is created in induction motor mainly by numbers solid copper bars which are shorted at both ends in such a manner that they form a cylinder cage like structure. This is why this motor is also referred as squirrel cage induction motor. Anyway let’s come to the basic point of three phase induction motor – which will help us to understand clearly about motor thermal overload protection . As the rotating magnetic flux cuts each of the bar conductor of rotor, there will be an induced circulating current flowing through the bar conductors. At starting the rotor is stand still and stator field is rotating at synchronous speed, the relative motion between rotating field and rotor is maximum. Hence the rate of cuts of flux with rotor bars is maximum, the induced current is maximum at this condition. But as the cause of induced current is, this relative speed, the rotor will try to reduce this relative speed and hence it will start rotating in the direction of rotating magnetic field to catch the synchronous speed. As soon as the rotor will come to the synchronous speed this relative speed between rotor and rotating magnetic field becomes zero, hence there will not be any further flux cutting and consequently there will not be any induced current in the rotor bars. As the induced current becomes zero, there will not be any further need of maintaining zero relative speed between rotor and rotating magnetic field hence rotor speed falls. As soon as the rotor speed falls the relative speed between rotor and rotating magnetic field again acquires a non zero value which again causes induced current in the rotor bars then rotor will again try to achieve the synchronous speed and this will continue till the motor is switch on. Due to this phenomenon the rotor will never achieve the synchronous speed as well as it will never stop running during normal operation. The difference between the synchronous speed with rotor speed in respect of synchronous speed, is termed as slip of induction motor. The slip in a normally running induction motor typically varies from 1% to 3 % depending upon the loading condition of the motor. Now we will try to draw speed current characteristics of induction motor – let’s have an example of large boiler fan. In the characteristic Y axis is taken as time in second, X axis is taken as % of stator current. When rotor is stand still that is at starting condition, the slip is maximum hence the induced current in the rotor is maximum and due to transformation action, stator will also draw a heavy current from the supply and it would be around 600% of the rated full load stator current. As the rotor is being accelerated the slip is reduced, consequently the rotor current hence stator current falls to around 500% of the full load rated current within 12 seconds when the rotor speed attains 80% of synchronous speed. After that the stator current falls rapidly to the rated value as the rotor reaches its normal speed. Now we will discuss about thermal over loading of electrical motor or over heating problem of electric motor and the necessity of motor thermal overload protection . Whenever we think about the overheating of a motor, the first thing strikes in our mind is over loading. Due to mechanical over loading of the motor draws higher current from the supply which leads to excessive over heating of the motor. The motor can also be excessively over heated if the rotor is mechanically locked i.e. becomes stationary by any external mechanical force. In this situation the motor will draw excessively high current from the supply which also leads to thermal over loading of electrical motor or excessive over heating problem. Another cause of overheating is low supply voltage. As the power id drawn by the motor from the supply depends upon the loading condition of the motor, for lower supply voltage, motor will draw higher current from mains to maintain required torque. Single phasing also causes thermal over loading of motor . When one phase of the supply is out of service, the remaining two phases draw higher current to maintain required load torque and this leads to overheating of the motor. Unbalance condition between three phases of supply also causes over heating of the motor winding, as because unbalance system results to negative sequence current in the stator winding. Again, due to sudden loss and reestablish of supply voltage may cause excessive heating of the motor. Since due to sudden loss of supply voltage, the motor is de-accelerated and due to sudden reestablishment of voltage the motor is accelerated to achieve its rated speed and hence for that motor draws higher current form the supply. As the thermal over loading or over heating of the motor may lead to insulation failure and damage of winding, hence for proper motor thermal overload protection , the motor should be protected against the following conditions Mechanical over loading, Stalling of motor shaft, Low supply voltage, Single phasing of supply mains, Unbalancing of supply mains, Sudden Loss and rebuilding of supply voltage. The most basic protection scheme of the motor is thermal over load protection which primarily covers the protection of all the above mentioned condition. To understand the basic principle of thermal over load protection let’s examine the schematic diagram of basic motor control scheme. In the figure above, when START push is closed, the starter coil is energized through the transformer. As the starter coil is energized, normally open (NO) contacts 5 are closed hence motor gets supply voltage at its terminal and it starts rotating. This start coil also closes contact 4 which makes the starter coil energized even the START push button contact is released from its close position. To stop the motor there are several normally closed (NC) contacts in series with the starter coil as shown in the figure. One of them is STOP push button contact. If the STOP push button is pressed, this button contact opens and breaks the continuity of the starter coil circuit consequently makes the starter coil de-energized. Hence the contact 5 and 4 come back to their normally open position. Then, in absence of voltage at motor terminals it will ultimately stop running. Similarly any of the other NC contacts (1, 2 & 3) connected in series with starter coil if open; it will also stop the motor. These NC contacts are electrically coupled with various protection relays to stop operation of the motor in different abnormal conditions. Let’s look at the thermal over load relay and its function in motor thermal overload protection. The secondary of the CTs in series with motor supply circuit, are connected with a bimetallic strip of the thermal over load relay (49). As shown in the figure below, when current through the secondary of any of the CTs, crosses it’s predetermined values for a predetermined time, the bi-metallic strip is over heated and it deforms which ultimately causes to operate the relay 49. As soon as the relay 49 is operated, the NC contacts 1 and 2 are opened which de-energizes the starter coil and hence stop the motor. Another thing we have to remember during providing motor thermal overload protection. Actually every motor does have some predetermined overload tolerance value. That means every motor may run beyond its rated load for a specific allowable period depending on its loading condition. How long a motor can run safely for a particular load is specified by the manufacturer. The relation between different loads on motor and corresponding allowable periods for running the same in safe condition is referred as thermal limit curve of the motor. Let’s look at the curve of a particular motor, given below. Here Y axis or vertical axis represents the allowable time in seconds and X axis or horizontal axis represents percentage of overload. Here it is clear from the curve that, motor can run safely without any damage due to overheating for prolonged period at 100% of the rated load. It can run safely 1000 seconds at 200% of normal rated load. It can run safely 100 seconds at 300% of normal rated load. It can run safely 15 seconds at 600% of normal rated load. The upper portion of the curve represents the normal running condition of the rotor and the lower most portion represents the mechanical locked condition of the rotor. Now the operating time Vs actuating current curve of the chosen thermal over load relay should be situated below the thermal limit curve of the motor for satisfactory and safe operation. Let’s have a discussion on more details- Remember the characteristics of starting current of the motor – During start up of the induction motor, the stator current goes beyond 600% of normal rated current but it stays up to 10 to 12 seconds after that stator current suddenly falls to normal rated value. So if the thermal overload relay is operated before that 10 to 12 seconds for the current 600% of normal rated then the motor cannot be started. Hence it can be concluded that the operating time Vs actuating current curve of the chosen thermal over load relay should be situated below the thermal limit curve of the motor but above the starting current characteristics curve of the motor. Probable position of the thermal current relay characteristics is bounded by these two said curves as shown in the graph by highlighted area. Another thing has to be remembered during choosing of thermal overload relay. This relay is not an instantaneous relay. It has a minimum delay in operation as the bimetallic strip required a minimum time to be heated up and deformed for maximum value of operating current. From the graph it is found that the thermal relay will be operated after 25 to 30 seconds if either the rotor is suddenly mechanically blocked or motor is fail to start. At this situation the motor will draw a huge current from the supply. If the motor is not isolated sooner, severer damage may occur. This problem is overcome by providing time over current relay with high pickup. The time current characteristics of these over current relays are so chosen that for lower value of over load, the relay will not operate since thermal overload relay will be actuated before it. But for higher value of overload and for blocked rotor condition time over load relay will be operated instead of thermal relay because former will actuate much before the latter. Hence both the bimetallic over load relay and time over current relay are provided for complete motor thermal overload protection. There is one main disadvantage of bimetallic thermal over load relay, as the rate of heating and cooling of bi-metal is affected by ambient temperature, the performance of the relay may differ for different ambient temperatures. This problem can be overcome by using RTD or resistance temperature detector. The bigger and more sophisticated motors are protected against thermal over load more accurately by using RTD. In stator slots, RTDs are placed along with stator winding. Resistance of the RTD changes with changing temperature and this changed resistive value is sensed by a Wheatstone bridge circuit. This motor thermal overload protection scheme is very simple. RTD of stator is used as one arm of balanced Wheatstone bridge. The amount of current through the relay 49 depends upon the degree of unbalancing of the bridge. As the temperature of the stator winding is increased, the electrical resistance of the detector increases which disturbs the balanced condition of the bridge. As a result current start flowing through the relay 49 and the relay will be actuated after a predetermined value of this unbalanced current and ultimately starter contact will open to stop the supply to the motor.

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Trip Circuit Supervision

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There are different contacts connected in series along a trip circuit of a electrical circuit breaker. There must be some situation when the circuit breaker should not trip even a faulty current passes through its power contacts. Such situations are low gas pressure in SF 6 circuit breaker, low air pressure in pneumatic operated circuit breaker etc. In this situation the trip coil of the CB must not be energized to trip the CB. So there must be NO contacts associated with gas pressure and air pressure relays, connected in series with breaker trip coil. Another scheme of trip coil is that it should not be re energized once the circuit breaker is open. That is done by providing one NO contact of breaker auxiliary switch in series with trip coil. In addition to that the trip circuit of a CB has to pass through considerable numbers of intermediate terminal contacts in relay, control panel and circuit breaker kiosk. So if any of the intermediate contacts is detached, the circuit breaker fails to trip. Not only that, if dc supply to the trip circuit fails, the CB will not trip. To overcome this abnormal situation, trip circuit supervision becomes very necessary. The figure below shows the simplest form of trip circuit healthy scheme. Here one series combination of one lamp, one push bottom and one resistor is connected across the protective relay contact as shown. In healthy situation all the contacts except protective relay contact are in close position. Now if push bottom (PB) is pressed, the trip circuit supervision network is completed and lamp glows indicating that the breaker is ready for tripping. The above scheme is for supervision while circuit breaker is closed. This scheme is called post close supervision. There is another supervision scheme which is called pre and post close supervision. This trip circuit supervision scheme is also quite simple. The only difference is that here in this scheme, one NC contact of same auxiliary switch is connected across the auxiliary NO contact of the trip circuit. The auxiliary NO contact is closed when CB is closed and auxiliary NC contact is closed when CB is open and vice versa. Hence, as shown in the figure below when the circuit breaker is closed the trip circuit supervision network is completed via auxiliary NO contact but when the circuit breaker is open the same supervision network is completed via NC contact. The resistor is used series with the lamp for preventing unwanted tripping of circuit breaker due to internal short circuit caused by failure of the lamp. So far whatever we have discussed it is only for local controlled installation but for a distance control installation, relay system is necessary. The figure below shows the trip circuit supervision scheme wherever a remote signal is required. When trip circuit is healthy and circuit breaker is closed, relay A is energized which closes the NO contact A 1 and hence relay C is energized. Energized relay C keeps NC contact in open position. Now if the circuit breaker is open, relay B is energized which closes No contact B 1 hence relay C is energized. As C is energized, it keeps the NC contact C 1 in open position. While CB is closed, if there is any discontinuity in the trip circuit relay A is de-energized which opens contact A 1 and consequently relay C is de-energized and which make the NC contact C 1 in close position and hence alarm circuit is actuated. Trip circuit supervision is experienced by relay B with the circuit breaker is open in a similar manner as relay A with the circuit breaker is closed. Relays A and C are time-delayed by copper slugs to prevent spurious alarms during tripping or closing operations. The resistors are mounted separately from the relays and their values are chosen such that if any one component is inadvertently short-circuited, a tripping operation will not take place. The alarm circuit supply should be separated from main trip supply so that the alarm can be actuated even the trip supply is fail.

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Busbar Protection,Busbar Differential Protection Scheme

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In early days only conventional over current relays were used for busbar protection . But it is desired that fault in any feeder or transformer connected to the busbar should not disturb busbar system.  In viewing of this time setting of busbar protection relays are made lengthy. So when faults occurs on busbar itself, it takes much time to isolate the bus from source which may came much damage in the bus system. In recent days, the second zone distance protection relays on incoming feeder, with operating time of 0.3 to 0.5 seconds have been applied for busbar protection . But this scheme has also a main disadvantage. This scheme of protection can not discriminate the faulty section of the busbar. Now days, electrical power system deals with huge amount of power. Hence any interruption in total bus system causes big loss to the company. So it becomes essential to isolate only faulty section of busbar during bus fault. Another drawback of second zone distance protection scheme is that, sometime the clearing time is not short enough to ensure the system stability. To overcome the above mentioned difficulties, differential busbar protection scheme with an operating time less than 0.1 sec., is commonly applied to many SHT bus systems. Differential Busbar Protection Current Differential Protection The scheme of busbar protection , involves, Kirchoff’s current law, which states that, total current entering an electrical node is exactly equal to total current leaving the node. Hence, total current entering into a bus section is equal to total current leaving the bus section. The principle of differential busbar protection is very simple. Here, secondaries of CTs are connected parallel. That means, S 1 terminals of all CTs connected together and forms a bus wire. Similarly S 2 terminals of all CTs connected together to form another bus wire. A tripping relay is connected across these two bus wires. Here, in the figure above we assume that at normal condition feed, A, B, C, D, E & F carries current I A , I B , I C , I D , I E and I F . Now, according to Kirchoff’s current law, Essentially all the CTs used for differential busbar protection are of same current ratio. Hence, the summation of all secondary currents must also be equal to zero. Now, say current through the relay connected in parallel with all CT secondaries, is i R , and i A , i B , i C , i D , i E and i F are secondary currents. Now, let us apply KCL at node X. As per KCL at node X, So, it is clear that under normal condition there is no current flows through the busbar protection tripping relay. This relay is generally referred as Relay 87. Now, say fault is occurred at any of the feeders, outside the protected zone. In that case, the faulty current will pass through primary of the CT of that feeder. This fault current is contributed by all other feeders connected to the bus. So, contributed part of fault current flows through the corresponding CT of respective feeder. Hence at that faulty condition, if we apply KCL at node K, we will still get, i R = 0. That means, at external faulty condition, there is no current flows through relay 87. Now consider a situation when fault is occurred on the bus itself. At this condition, also the faulty current is contributed by all feeders connected to the bus. Hence, at this condition, sum of all contributed fault current is equal to total faulty current. Now, at faulty path there is no CT. (in external fault, both fault current and contributed current to the fault by different feeder get CT in their path of flowing). The sum of all secondary currents is no longer zero. It is equal to secondary equivalent of faulty current. Now, if we apply KCL at the nodes, we will get a non zero value of i R . So at this condition current starts flowing through 87 relay and it makes trip the circuit breaker corresponding to all the feeders connected to this section of the busbar. As all the incoming and outgoing feeders, connected to this section of bus are tripped, the bus becomes dead. This differential busbar protection scheme is also referred as current differential protection of busbar. Differential Protection of Sectionalized Bus During explaining working principle of current differential protection of busbar, we have shown a simple non sectionalized busbar. But in moderate high voltage system electrical bus sectionalized in than one sections to increase stability of the system. It is done because, fault in one section of bus should not disturb other section of the system. Hence during bus fault, total bus would be interrupted. Let us draw and discuss about protection of busbar with two sections. Here, bus section A or zone A is bounded by CT 1 , CT 2 and CT 3 where CT 1 and CT 2 are feeder CTs and CT 3 is bus CT. Similarly bus section B or zone B is bounded by CT 4 , CT 5 and CT 6 where CT 4 is bus CT, CT 5 and CT 6 are feeder CT. Therefore, zone A and B are overlapped to ensure that, there is no zone left behind this busbar protection scheme. ASI terminals of CT 1 , 2 and 3 are connected together to form secondary bus ASI BSI terminals of CT 4 , 5 and 6 are connected together to form secondary bus BSI. S 2 terminals of all CTs are connected together to form a common bus S 2 . Now, busbar protection relay 87A for zone A is connected across bus ASI and S 2 . Relay 87B for zone B is connected across bus BSI and S 2 . This section busbar differential protection scheme operates in some manner simple current differential protection of busbar. That is, any fault in zone A, with trip only CB 1 , CB 2 and bus C B . Any fault in zone B, will trip only CB 5 , CB 6 and bus CB. Hence, fault in any section of bus will isolate only that portion from live system. In current differential protection of busbar, if CT secondary circuits, or bus wires is open the relay may be operated to isolate the bus from live system. But this is not desirable. DC Circuit of Differential Busbar Protection A typical DC circuit for busbar differential protection scheme is given below. Here, CSSA and CSSB are two selector switch which are used to put into service, the busbar protection system for zone A and zone B respectively. If CSSA is in “IN” position, protection scheme for zone A is in service. If CSSB is in “IN” position, protection for zone B is in service. Generally both of the switches are in “IN’ position in normal operating condition. Here, relay coil of 96A and 96B are in series with differential busbar protection relay contact 87A-1 and 87B-1 respectively. 96A relay is multi contacts relay. Each circuit breaker in zone A is connected with individual contact of 96A. Similarly, 96B is multi contacts relay and each circuit breaker in zone-B is connected with individual contacts of 96B. Although here we use only one tripping relay per protected zone, but this is better to use one individual tripping relay per feeder. In this scheme one protective relay is provided per feeder circuit breaker, whereas two tripping relays one for zone A and other for zone B are provided to bus section or bus coupler circuit breaker. On an interval fault in zone A or bus section A, the respective bus protection relay 87A, be energized whereas during internal fault in zone B, the respective relay 87B will be energized. As soon as relay coil of 87A or 87B is energized respective no. contact 87A-1 or 87B-1 is closed.Hence, the tripping relay 96 will trip the breakers connected to the faulty zone. To indicate whether zone A or B busbar protection operated, relay 30 is used. For example, if relay 87A is operated, corresponding “No” contact 87A-2 is closed which energized relay 30A. Then the No contact 30A-1 of relay 30A is closed to energized alarm relay 74. Supervision relay 95 of respective zone is also energized during internal fault, but it has a time delay of 3 second. So, it reset as soon as the fault is cleared and therefore does not pick up zone bus wire shorting relay 95x which in turn shorts out the bus wires. An alarm contact is also given to this auxiliary 95x relay to indicate which CT is open circuited. No volt relay 80 is provided in both trip and non-trip section of the D. C. circuit of differential busbar protection system to indicate any discontinuity of D. C. supply. Voltage Differential Protection of Busbar The current differential scheme is sensitive only when the CTs do not get saturated and maintain same current ratio, phase angle error under maximum faulty condition. This is usually not 80, particularly, in the case of an external fault on one of the feeders. The CT on the faulty feeder may be saturated by total current and consequently it will have very large errors. Due to this large error, the summation of secondary current of all CTs in a particular zone may not be zero. So there may be a high chance of tripping of all circuit breakers associated with this protection zone even in the case of an external large fault. To prevent this maloperation of current differential busbar protection, the 87 relays are provided with high pick up current and enough time delay. The greatest troublesome cause of current transformer saturation is the transient dc component of the short circuit current. This difficulties can be overcome by using air core CTs. This current transformer is also called linear coupler. As the core of the CT does not use iron the secondary characteristic of these CTs, is straight line. In voltage differential busbar protection the CTs of all incoming and outgoing feeders are connected in series instead of connecting them in parallel. The secondaries of all CTs and differential relay form a closed loop. If polarity of all CTs are properly matched, the sum of voltage across all CT secondaries is zero. Hence there would be no resultant voltage appears across the differential relay. When a buss fault occurs, sum of the all CT secondary voltage is no longer zero. Hence, there would be current circulate in the loop due to the resultant voltage. As this loop current also flows through the differential relay, the relay is operated to trip all the circuit beaker associated with protected bus zone. Except when ground fault current is severally limited by neutral impedance there is usually no selectivity problem When such a problem exists, it is solved by use of an additional more sensitive relaying equipment including a supervising protective relay.

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Pick Up Current,Current Setting,Plug Setting Multiplier and Time Setting Multiplier of Relay

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During study of electrical protective relays, some special terms are frequently used. For proper understanding, the functions of different protective relays, the definition of such terms must be understood properly. Such terms are, Pick up current. Current setting. Plug setting multiplier (PSM). Time setting multiplier (TSM). Pick Up Current of Relay In all electrical relays, the moving contacts are not free to move. All the contacts remain in their respective normal position by some force applied on them continuously. This force is called controlling force of the relay. This controlling force may be gravitational force, may be spring force, may be magnetic force. The force applied on the relay’s moving parts for changing the normal position of the contacts, is called deflecting force. This deflecting force is always in opposition of controlling force and presents always in the relay. Although the deflecting force always presents in the relay directly connected to live line, but as the magnitude of this force is less than controlling force in normal condition, the relay does not operate. If the actuating current in the relay coil increases gradually, the deflecting force in electro mechanical relay, is also increased. Once, the deflecting force crosses the controlling force, the moving parts of the relay initiate to move to change the position of the contacts in the relay. The current for which the relay initiates it operation is called pick up current of relay . Current Setting of Relay The minimum pick up value of the deflecting force of an electrical relay is constant. Again the deflecting force of the coil is proportional to its number of turns and current flowing through the coil. Now, if we can change the number of active turns of any coil, the required current to reach at minimum pick value of the deflecting force, in the coil also changes. That means if active turns of the relay coil is reduced, then proportionately more current is required to produce desired relay actuating force. Similarly if active turns of the relay coil is increased, then proportionately reduced current is required to produce same desired deflecting force. Practically same model relays may be used in different systems. As per these systems requirement the pick up current of relay is adjusted. This is known as current setting of relay. This is achieved by providing required number of tapping in the coil. These taps are brought out to a plug bridge. The number of active turns in the coil can be changed by inserting plug in different points in the bridge. The current setting of relay is expressed in percentage ratio of relay pick up current to rated secondary current of CT. That means, For example, suppose, you want that, an over current relay should operate when the system current just crosses 125% of rated current. If the relay is rated with 1 A, the normal pick up current of the relay is 1 A and it should be equal to secondary rated current of current transformer connected to the relay. Then, the relay will be operated when the current of CT secondary becomes more than or equal 1.25 A. As per definition, The current setting is sometimes referred as current plug setting. The current setting of over current relay is generally ranged from 50% to 200%, in steps of 25%. For earth fault relay it is from 10% to 70% in steps of 10%. Plug Setting Multiplier of Relay Plug setting multiplier of relay is referred as ratio of fault current in the relay to its pick up current. Suppose we have connected on protection CT of ratio 200/1 A and current setting is 150%. Hence, pick up current of the relay is, 1 × 150 % = 1.5 A Now, suppose fault current in the CT primary is 1000 A. Hence, fault current in the CT secondary i.e. in the relay coil is, 1000 × 1/200 = 5 A Therefore PSM of the relay is, 5 / 1.5 =3.33 Time Setting Multiplier of Relay The operating time of an electrical relay mainly depends upon two factors : How long distance to be traveled by the moving parts of the relay for closing relay contacts and How fast the moving parts of the relay cover this distance. So far adjusting relay operating time, both of the factors to be adjusted. The adjustment of travelling distance of an electromechanical relay is commonly known as time setting. This adjustment is commonly known as time setting multiplier of relay . The time setting dial is calibrated from 0 to 1 in steps 0.05 sec. But by adjusting only time setting multiplier, we can not set the actual time of operation of an electrical relay. As we already said, the time of operation also depends upon the speed of operation. The speed of moving parts of relay depends upon the force due to current in the relay coil. Hence it is clear that, speed of operation of an electrical relay depends upon the level of fault current. In other words, time of operation of relay depends upon plug setting multiplier. The relation between time of operation and plug setting multiplier is plotted on a graph paper and this is known as time / PSM graph. From this graph one can determine, the total time taken by the moving parts of an electromechanical relay, to complete its total travelling distance for different PSM. In time setting multiplier, this total travelling distance is divided and calibrated from 0 to 1 in steps of 0.05. So when time setting is 0.1, the moving parts of the relay has to travel only 0.1 times of the total travelling distance, to close the contact of the relay. So, if we get total operating time of the relay for a particular PSM from time / PSM graph and if we multiply that time with the time setting multiplier, we will get, actual time of operation of relay for said PSM and TSM. For getting clear idea, let us have a practical example. Say a relay has time setting 0.1 and you have to calculate actual time of operation for PSM 10. From time / PSM graph of the relay as shown below, we can see the total operating time of the relay is 3 seconds. That means, the moving parts of the relay take total 3 seconds to travel 100% travelling distance. As the time setting multiplier is 0.1 here, actually the moving parts of the relay have to travel only 0.1 × 100% or 10% of the total travel distance, to close the relay contacts. Hence, actual operating time of the relay is 3 × 0.1 = 0.3 sec. i.e. 10% of 3 sec. Time vs PSM Curve of Relay This is relation curve between operating time and plug setting multiplier of an electrical relay. The x-axis or horizontal axis of the Time / PSM graph represents, PSM and Y-axis or vertical axis represents time of operation of the relay. The time of operation represents in this graph is that, which required to operate the relay when time setting multiplier set at 1. From the Time / PSM curve of a typical relay shown below, it is seen that, if PSM is 10, the time of operation of relay is 3 sec. That means, the relay will take 3 seconds to complete its operation, with time setting 1. It is also seen from the curve that, for lower value of plug setting multiplier, i.e. for lower value of fault current, the time of operation of the relay is inversely proportional to the fault current. But when PSM becomes more than 20, the operating time of relay becomes almost constant. This feature is necessary in order to ensure discrimination on very heavy fault current flowing through sound feeders. Calculation of Relay Operation Time For calculating actual relay operating time, we need to know these following operation. Current setting. Fault current level. Ratio of current transformer. Time / PSM curve. Time setting. Step – 1 From CT ratio, we first see the rated secondary current of CT. Say the CT ratio is 100 / 1 A, i.e. secondary current of CT is 1 A. Step – 2 From current setting we calculate the trick current of the relay. Say current setting of the relay is 150% therefore pick up current of the relay is 1 × 150% = 1.5 A. Step – 3 Now we have to calculate PSM for the specified faulty current level. For that, we have to first divide primary faulty current by CT ratio to get relay faulty current. Say the faulty current level is 1500 A, in the CT primary, hence secondary equivalent of faulty current is 1500/(100/1) = 15 A Step – 4 Now, after calculating PSM, we have to find out the total time of operation of the relay from Time / PSM curve. From the curve, say we found the time of operation of relay is 3 second for PSM = 10. Step – 5 Finally that operating time of relay would be multiplied with time setting multiplier, in order to get actual time of operation of relay. Hence say time setting of the relay is 0.1. Therefore actual time of operation of the relay for PSM 10, is 3 × 0.1 = 0.3 sec or 300 ms.  

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