Majibu ya tatizo lako yapo hapa chini, lakini naomaba ufungue link husika usome vizuri.
Kabla ya yote jaribu kubadili hizo phase mbili wakati moja ipo pale pale yaani kama RYB basi badili YB kuwa BY huku R ikibaki palepale, hivyo itakuwa RBY, hivyo kama bado badili RY wakati B ikiwa palepale, kama bado jaribu RB wakati Y ipo palepale ikishindikana endelea na maelezo hayo hapa chini kupima phase angle na phase sequence kama ilivyo elekezwa.
An application where both phase sequence and phase angle is important–Paralleling two transformers in a low voltage substation.
Often times it is desired to close the tie breaker and parallel the two medium voltage transformers for meeting the load requirement or some other requirements. Two things need to be performed (in the order) pertaining to phase sequence to make sure things work as intended.
- Check Phase Sequence:Using phase sequence meter , ascertain that the two sources have similar phase sequence, either both having ABC sequence or both having ACB sequence.
- Check Phase Angle: Measure the potential difference between the respective phases that is going to be paralleled. The magnitude of the potential difference between the corresponding phase will indicate the phase angle difference between the two sources. Ideally no potential difference should exist between say phase A of source 1 and phase A of source B if both sources have phases that are exactly at 0, 120, 240 degrees apart. Minor phase angle differences can usually be tolerated and it will only result in circulating ground current between the transformers. This test can also be done by using an oscilloscope. If large phase angle difference is noticed additional engineering need to be performed prior to paralleling two transformers.
Possible consequences of not checking the phase sequence while connecting devices:
- Motors could rotate in the opposite direction and depending on the driven load it can damage the driven load.
- Electromechanical relays could nuisance trip or worst not function at all.
- Electromechanical power meters could give erroneous reading.
- Dangerous short circuit current can flow while interconnecting sources with different phase rotation/sequence.
Possible consequences of not checking the phase angle while connecting devices:
- Circulating phase current between the two sources which could result in overheated transformers.
- Circulating ground currents between the two sources.
- Circulating ground currents causing nuisance trip on ground fault relays.
LINK ya maelezoyote hii hapa Phase Sequence and Phase Angle – Voltage Disturbance
UKIFANIKIWA NJOO UNIPE MREJESHO TUTASAIDIA WENGI, SIO MBAYA UKINIRUSHIA BIA MBILI.
Hutoamini ndugu kwamba phase sequence na rotation zimefanyika correctly na hapa hakuna transformers zilizoungwa parallel.
Hii inteconnector katikati hakuna load yoyote wala nini. Na zaidi ni kwamba tapping area, huko itokako machine hazibehave namna hii.
Tumejaribu disconnect hii incomer mpya tuliyoijenga na ku feed na supply nyingine inatulia fresh.
Tume troubleshoot possibilities zote ila inakataa.
Pia nakumbuka mwezi uliopita katika wilaya iyoiyo kila ilipokua ikifika saa 4-5 usiku gridi ilikua inatoka kwa indication ya earth fault, yukasurvey na kupatrol line yote tukaclear bushes zote near line, tukaangalia discs zote kama zina fructurers, tukaangalia arrestors za kila transformer tukaangalia jumpers zote hakukua na shida yoyote na bado line ilikua inatoka saa ile ile na mda ule ule kwa indication ile ile (earth fault).
Tulifanya sagging upya karibu vipande vyote vilivyokua vinahisiwa but the problem was the same, ila ajabu tukiwasha mashine( diesel generator) badala ya grid, mzigo unakaa usiku wote.
Mwezi mzima ilikua ni tabu ya namna hii, tukadhani probably earth shield wire imeguswa na phase yeyote, no way.
Mwishoni tuligundua it was a nearby district prpblem, they had poor sagging. Tulipo kiondoa kile kipande after a month, line ilikaa hadi leo.
Em tuanze upya. I hope tutafika, thanks kwa ushauri pia.