To day, I came across a special problem. we have 500 KVA Transformer - 11kv/433V connected to Power Control Centre (PCC).
We have 250 KVA new DG , just commissioned, Leroy Somer make Alternator , connected to same Power control Centre, with seperate breaker.
We have 20KVAR * * stage Automatic power factor correction bank in the same PCC.
Now, till today, on Mains supply, APFC bank with L&T MRPM14 APFC instrument is functioning alright, increasing the capacitors with increase in load, & decreasing the stages of capacitors with decrease in load.
But, when Mains is OFF, & DG supply is started, APFC malfunctions - & all the 14 stages are one after the other, ON in the circuit.
APFC reading always shows the low, lagging!
again, switching back to the mains, APFC functions very normal !
Just to tell you in specific detail...
Sensing CT is placed in the Mains supply BUS., not in DG I/C Bus, which is normal
Sensing Voltage is takenfrom R phase of the PCC Out let Bus ( Common to DG & Mains)
Exploring the Science of Electricity