overcurrent and undervoltage relay coordination

[brainsalad]

Greetings:

Wondering if anyone can share their thoughts on (4.16kV/480V) overcurrent and undervoltage relay coordination. A range of fault currents (three-phase,line-to-ground,line-to-line,line-line-ground) and corresponding post-fault bus voltages could be calculated and compared to the UV dropout voltage. Operating time between UV and OC relays is compared. Operating times of 4.16kV and 480V is checked for selectivity. Thanks for your thoughts.

 

[pwrtran]

Is that a load customer or a generation customer?

 

[brainsalad]

Pwrtran: thanks for your inquiry, however I am just interested to know what others general methodology is for coordinating overcurrent and undervoltage relay operation.

 

[pwrtran]

If it is just a normal load customer with no particular sensitive devices then an o/c protection is adequate.