Sometimes we experience that a primary High Voltage relay is cutting out the HV feeder even with smaller electrical faults secondary on a 4160/480 transformer.
The (old) electromechanical Westinghouse relay CO-6 50/51N has a Time Dial 1 - Amp.Taps 0.5 - CT 600/5
As I see it, the Amp Taps will cause a cut out with a current larger than 60A primary in more than 0.85 sec. (or is it 90A ? ? here I have my doubts)
To prevent those unintended cut out, I want to Increase the amp. range on my CO-6 relay.
To create an acceptable selectivity to the CO-8 51 relays (Time Dial 3 ? Amp.Taps 5 ? CT 600/5) I have in plans to increase the CO-6 amps to about 2000-5000A and to lower the Time Dial to 0.5 in order to spare the feeder if a cable fault should happen.
An amp. increase like this seems a little drastic to me, but it will meet all European regulations. Will it meet the US standards as well, referring to normal settings of a CO-6?
The HV feeder is an AWG 4/0 and the 1000 KVA transformer has a 200A load interrupter before and 1600A over current protection after the transformer.
Thanks,
Lars
The (old) electromechanical Westinghouse relay CO-6 50/51N has a Time Dial 1 - Amp.Taps 0.5 - CT 600/5
As I see it, the Amp Taps will cause a cut out with a current larger than 60A primary in more than 0.85 sec. (or is it 90A ? ? here I have my doubts)
To prevent those unintended cut out, I want to Increase the amp. range on my CO-6 relay.
To create an acceptable selectivity to the CO-8 51 relays (Time Dial 3 ? Amp.Taps 5 ? CT 600/5) I have in plans to increase the CO-6 amps to about 2000-5000A and to lower the Time Dial to 0.5 in order to spare the feeder if a cable fault should happen.
An amp. increase like this seems a little drastic to me, but it will meet all European regulations. Will it meet the US standards as well, referring to normal settings of a CO-6?
The HV feeder is an AWG 4/0 and the 1000 KVA transformer has a 200A load interrupter before and 1600A over current protection after the transformer.
Thanks,
Lars