A yayin daidai, zama’ar halitta ta sarrafa’u na distribution transformers yana dawo gaba biyu:
zama’ar halitta akan high-voltage (HV) winding da low-voltage (LV) winding plus tank na sarrafan, da
zama’ar halitta akan LV winding da HV winding plus tank na sarrafan.
Idan kowane dabi’a daga cikin wasu biyu ya samu darajar da a yarda da shi, yana nuna cewa zama’ar halitta akan gwaji HV, LV, da tank na sarrafan suna da kyau. Idan wanda daga cikinsu baya yi kyau, dole ne a dawo zama’ar halitta bisa biyu akan kowane sashe daga cikin uku (HV–LV, HV–tank, LV–tank) don gano wace cira mai tsinkin halitta take.
1. Kayan Aiki da Alamar Dawo
Sauraro dawo zama’ar halitta na sarrafan 10 kV distribution transformer, wadannan kayan aiki da alamar su bukatar:
2500 V insulation resistance tester (megohmmeter)
1000 V insulation resistance tester
Discharge rod
Voltage detector (voltage tester)
Grounding cables
Shorting leads
Insulating gloves
Adjustable wrench
Screwdrivers
Lint-free cloth (misali, gauze)
Kafin amfani, duba duk kayan aiki da alamar don gano karuwa kuma tabbata cewa suna cikin lokacin da aka yarda da safe testing. Sai dai, dawo open-circuit da short-circuit akan alamar dawo zama’ar halitta don tabbatar da ake yi aiki da sahih.
2. Canza Sarrafa Daga Halin Amfani Zuwa Halin Gudanarwa
Don canza sarrafa gida zuwa halin gudanarwa:
Mallakar gudanarwa dole ne suyi work permit, wacce zai ci gaba ta hanyar approval.
Bayan izinin tambayar, masu shirya a wurin amfani za barabarta loadin LV, zabi fuses na HV, kuma za hada wuri da a ga shi.
Masu gudanarwa sunsa za yi discharge, tabbatar da voltage, saita grounding lines, da saita barriers da alamar warning.
3. Dawo Zama’ar Halitta
Sarrafen da ke cikin halin gudanarwa:
Cire duk HV da LV leads daga bushing terminals.
Talla matafiya HV da LV bushings ta hanyar lint-free cloth don kula da surface contamination yake magana kan damar.
Duba mataki ko cracks a bushings ta hanyar juyawa.
Bayan talla, yi short maimakon uku na HV bushing terminals da hudu na LV bushing terminals ta hanyar shorting leads.
Dawo 1: HV winding zuwa LV winding + tank
Yi amfani da 2500 V insulation resistance tester.
Short da ground tank na sarrafan da LV bushing terminals.
Hadna L (line) terminal na tester zuwa shorting lead na HV.
Hadna E (earth) terminal zuwa shorting lead na LV.
Idan bushings sun faru karuwa sosai, hadna G (guard) terminal ta hanyar wire da aka garawa a kashe HV bushing kusa da haɗin L (ba tare da zama mai zurfi L ba), tabbata cewa G tana da kyau a halitta daga E.
Dawo 2: LV winding zuwa HV winding + tank
Yi amfani da 1000 V insulation resistance tester.
Short da ground tank na sarrafan da HV bushing terminals.
Hadna L terminal zuwa shorting lead na LV.
Hadna E terminal zuwa shorting lead na HV.
Idan ke amfani da G terminal, garawa kabilin shi a kashe LV bushing ta hanyar sharuɗɗan sama.
4. Yanayin Dawo
(1) Kama da tsawon tushen bayan L, G, da E a lokacin iƙilafi. Tsiro tushen yana iya haifar da arcing tsakanin kabilo, yana kara leakage current tsakanin L da E, kuma yana kasa kyaukar damar.
(2) Insulation resistance tester ke baiwa rated voltage sai kawai idan crank speed ta 120 rpm. Kama da wannan speed a kowace lokaci a lokacin dawo, kuma kama da crank sai kawai kwanaki 1 kafin a rubuta daraja.
(3) Tsarin HV, tsarin LV, da tankin suna hadawa don kirkirar natsuwar yanayi mai yawa. Bayan loda alamar:
– Fara fassarar kayan ajiya daga transformer, sannan durkar cire maƙaƙan. Idan bai yi haka ba zai iya samar da damar transformer mai chargewa ya koma cikin tester, wanda zai iya tashi masa.
– Ku ladda transformer ta amfani da abubuwan laddawa kafin ku cire wani sadarwa na test.
(4) Bayan kama da gwadawa, rubuta girman tsakiyar yanki yayin lissafin kuma gyara darajar shiga na yaya zuwa 20°C don tabbatar da ingantacciyar gyara. Yi imanar sakamako da aka gyara da sharuddan da suka wuce da bayanan takaitattun – babu iyakar farko dole ne a ganu.
