SEL 351S Relays
SEL 351S Relays
(OP)
Hello:
We recently replaced our old main substation electromechanical relaying system with a SEL 351S/351A system. The 351A relays are for feeder protection and the 351S relays serve as main secondary breakers.
Our substation consists of 2ea power transformers (69kV/12.47kV, 15/20MVA ABB) feeding a dual lineup with a tie breaker. Each lineup has six feeders (12.47kV).
Each transformer has S&C Trans-Rupters on the primary side (with a Basler relay system for overcurrent protection)
We have to come up with 27 (UV), 59 (OV) and 81 settings for the 351S relays. I am hesistant to recommend settings based on the settings we had for the electromechanical over/undervoltage protection.
Any ideas, folks.
Thank you kindly in advance
We recently replaced our old main substation electromechanical relaying system with a SEL 351S/351A system. The 351A relays are for feeder protection and the 351S relays serve as main secondary breakers.
Our substation consists of 2ea power transformers (69kV/12.47kV, 15/20MVA ABB) feeding a dual lineup with a tie breaker. Each lineup has six feeders (12.47kV).
Each transformer has S&C Trans-Rupters on the primary side (with a Basler relay system for overcurrent protection)
We have to come up with 27 (UV), 59 (OV) and 81 settings for the 351S relays. I am hesistant to recommend settings based on the settings we had for the electromechanical over/undervoltage protection.
Any ideas, folks.
Thank you kindly in advance






RE: SEL 351S Relays
First, determine what functions are really necessary. The fewer functions enabled, the fewer nuisance trips you will experience. The 351 is a complicated relay - it really helps to keep it as simple as possible, at least initially.
If you decide you need undervoltage, overvoltage, 81O/U or whatever, the setting criteria will be no different than it would be for electromechanical relays. If you can provide additional information regarding your system, you'll probably get a lot of advice on settings. The 81 settings certainly must be coordinated with other frequency and load shedding relaying you have in the system.
RE: SEL 351S Relays
We have no load shedding scheme implemented at this time or other frequency relaying
When I set the old 27/59 electromechanical devices I had access to time-voltage curves, but with the 351S I have not been able to locate any.
Yes, I would appreciate advice on settings for this advanced circuit breaker.
What other information do I need to post?
Thank you,
hidalgoe
RE: SEL 351S Relays
RE: SEL 351S Relays
RE: SEL 351S Relays
As stevenal said, the 27/59 functions in the 351 are definite time, not inverse time. But you can have two levels with different time delays.
RE: SEL 351S Relays
Rafiq Bulsara
http://www.srengineersct.com
RE: SEL 351S Relays
RE: SEL 351S Relays
I appreciate your concern.
I have over 35 years of experience as a PE and power systems engineer. I have done projects for small and large industrial plants and for colleges, universities, hospitals and a few medium sized utilities.
My motivation was obtaining advice on a relay I am not familiar with since I was very much pressed for time.
Having read your considered and timely responses (and other colleagues responses) to varied electrical problems, I thought it would be proper to seek your advice.
However, I am grateful for your frankness.
Respectfully,
Hidalgoe,
RE: SEL 351S Relays
Cool! In that case, dpc already answered it.
Rafiq Bulsara
http://www.srengineersct.com
RE: SEL 351S Relays
I called a colleague who was familiar with the SEL 351S and discussed this relay's multi-functionality. We came to the conclusion that what I need is separate OV/UV protection; a relay that will provide the time-voltage characteristics that I want for OV/UV protection.
Thank you all for your help and consideration.
Respectfully,
hidalgoe
RE: SEL 351S Relays
I can't imagine why this would be necessary. You've never explained the purpose of the UV/OV protection, so it is difficult to comment on specifics. But whatever floats your boat. Good luck.