Thank you Nitesh. I really watch your videos regularly and your content is very helpful to understand these complex protection studies. I would like to request to please make videos on Bus Bar protection relays, as very few are experts in this field.
Niteshji आपके समझाने का तरीका बहुत अच्छा है | *सर आपसे एक बात जाननी है कि R. E. F. Protection, transformer के HV side के Relay panel मे ही क्यो इंस्टॉल किया जाता है |*
HV side ya LV side dono taraf laga sakte hai. Lekin uske liye jaruri hai ki HV & LV dono winding star honi chahiye. Bina neutral ka REF relay sense nahi karega.
Nice information collected and shared. Case Study: In case of large motor 11kv ,star connected , 1.8 mw , while replacing the faulty relay one of the line CT wiring got interchanged. Motor started tripping immediately on over current and unbalance. ABB Rem 620 doesn't have any clue for ct polarity check. can you pl share any details for the same.
Ct se rely ki wairing disturb ho hi he Or me Pakistan se hun Or me sarkari HUB Dam pumping station men electrical shop me hun or hum bus bar me ct rely or pory switch bord wiring chek Kar rahe he plz sir is me folt k se tres kryn?
In the other lecture about REF you described that Metrosil (VDR) suppress High Voltage spike that is generated across the NCT during Heavy fault current, but the VDR is not connected in this low impedance scheme whereas during heavy fault current NCT will see high voltage across the sec terminal (same as in high impedance case) .... How is this taken care in Low impedance scheme ? Thanks :)
Yes to limit the fault current. In generally 415 V is solidly earthed. 3.3, 6.6, 11 kv is earthed with NGR or neutral grounding resistor with earth fault current limited to 200 to 400A. This is the general Practice used in industry. EHV like 132, 220 or 400 kV are solidly earthed #ElectricalTechnologyAndIndustrialPractice
Big power utility companies and big industries in developed countries always add stabilising resistor and metrosil varistor with numerical relays like RET 670, Micom 632, SEL 787. There is no example that a numerical REF scheme is excluded with these components.
