One other aspect that will come into focus is how you connect your current transformers to
measure the fault current. A protection single line diagram would help understand the the co-ordination requirements
I agree with Scottty that no work is more important than human life....
But why not try this:-
Change the supply to the feeder on breaker A. Go the source of B and shift the cable terminations as below:
Y to R
R to B
B to Y
In doing this you shift the voltages +120 degrees according to your...
The change-over may work but consicer the commercial losses when the contactor fails. Before one get to discover the utility company may have lost quite some KWHrs.. A seperate meter may be the best solution commercially
With your single line diagram you will of course have sensing/relaying points. You must have the:
i) muximum fault currents for faults at these points
ii)minimum fault currents for faults at these points
iii) muximum through fault currents at these points
These basics plus all that you alredy...
Thank you. I thought the PFC could be injecting more VARs. I have to liase with the client to carry out the above checks. I will give you feedback soon.
We have a client metered on 11kV. From the breaker, the client has a breaker which switches on a 1.5MVA transformer on to a 415V bus.
The client has a power factor correction capacitor bank of 500KVA and the loading is mostly inductive.
The client has been complaining of high voltages between...
I had an almost similar problem when a genset breaker tripped on energizing a transformer. I think it may be inrush since I dilayed the operation on inrush a few more cycles and the problem was solved.
I would like to use the overvoltage function as to detect the zero sequence residual voltage and be able to trip the breaker on the trafo LV side.
The relay, 7RW6000-2EA00-0DA00/BB, seem trip only on the undervoltage function. It can detect and annunciate an overvoltage but I cant get the...
Yes, the VTs are positioned between the trafo and the autorecloser. There is a possibility of V connection and the broken delta connection. They are single phase units and I acn be able to connect them to suit my needs
Thank you
Hallo guys,
need help on the 7RW6000 undervoltage relay. Can this relay be connected on the delta side of a Star/Delta transformer to detect eartfaults in the transformer when the Delta side autorecloser is open.
Regards,
Punglu
It is obvious that technological advancements have enabled manufacturers to come up with relays with less VA requirements. Low impendance differential and REF schemes are gaining popularity but a change from the high impedance could be purely based on economic sense.
From the merits and...
We have undertaken studies on the cause of flashing on a yellow phase spout. The latest having destroyed the 11kV indoor CB. The CB was installed for a client whose load is mostly compressors, airconditioners and freezers. What could be the likely causes and what remedies do you suggest. This is...
Jghrist, I also felt BKR3 and BKR2 is superfluous but requirement for the utility is that we have BKR2 as the metering BKR. BKR3 is the Trafo BKR. No line are fed form any of the buses. All loads are fed from the 11kV bus. The CTs for Trafo protection are all bushing CTs, no extra CTs have been...
In some places you may be mislead by the insulators. I have to ares where insulators for 36 kV are used for 15 kV lines! You may have to get the exact voltages rather than judge by the no. of bells....
I appreciate. The numerical O/C relays are SPAJ 140C for O/C & residual E/F while the SBEF is for SBEF. BKR1 and BKR2 belong to the utility while BKR onwards is for the client.
How long should the last relay on the attached drawing (At the 33kV source Bus)take to initiate a trip to opening of the breaker?
I am trying to grade and give the customer (11 kV incomer breaker)some appreciable margin. Any standards used, may be in other utilities. Let me know please and...
I discovered that the earthing of the substation is poor and corrected it. I don't uderstand how this could cause so much interference but the problem seem to have eased.
