High Impedance Differential CTs
High Impedance Differential CTs
(OP)
I have a situation where it would be useful for me to put a CO relay in line with CTs that are currently only being used for BUS differential protection. That particular relay is an SEL 587Z. I know that in some places in our system, we have multiple relays on a single CT, although not with a 587Z. I have recently come across some documentation that says the 587Z should have dedicated CTs. I guess my question is will it work if I put the CO in line with the CTs if I add in the impedance that the CO will introduce to the overall CT circuit when doing my calculations. That burden is very small. Thanks in advance.






RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
jghrist is right that it will probably work for line faults, but not as well as might be expected. I'd try very hard to avoid the situation.
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs
Not everybody wires it for a summation.
But a 501 will do just as well, and is much more cost effective than a 487B.
Frankly, the 400 SEL relays are much over priced for what they do, for usage at lower voltages (230 kV and lower).
RE: High Impedance Differential CTs
RE: High Impedance Differential CTs