saladhawks
Electrical
- Jun 4, 2004
- 86
I have a cold load pickup (CLP) question related to a SEL-351R relay. SEL-351R relay protects a 4.36 kV 4-wire circuit with the following details:
- Peak Phase Load : 280 Amps
- 51P Pickup : 560 Amps
Circuit recently tripped during peak conditions and was out-of-service for 2+ hours. SEL-351R CLP settings are:
- Loss of Diversity Timer - 15 minutes
- Multiple of Min Phase Trip When CLP Active - 6x (3360 Amps)
- Time Current Below Min Trip to Exit CLP - 15 seconds
- Restore Min Trip Time Limit - Disabled
When circuit was restored, phase current was 500 Amps. CLP was active for 15 seconds until normal Min Trip settings were restored since phase current was below 3360 Amps.
For the next 15 minutes, phase current stayed at 500 Amps. Since the normal Min Trip setting is 560 Amps, circuit was close to tripping on load.
Are the above CLP settings common, as my experience has been to set CLP settings at 2x peak load current to avoid load trips?
- Peak Phase Load : 280 Amps
- 51P Pickup : 560 Amps
Circuit recently tripped during peak conditions and was out-of-service for 2+ hours. SEL-351R CLP settings are:
- Loss of Diversity Timer - 15 minutes
- Multiple of Min Phase Trip When CLP Active - 6x (3360 Amps)
- Time Current Below Min Trip to Exit CLP - 15 seconds
- Restore Min Trip Time Limit - Disabled
When circuit was restored, phase current was 500 Amps. CLP was active for 15 seconds until normal Min Trip settings were restored since phase current was below 3360 Amps.
For the next 15 minutes, phase current stayed at 500 Amps. Since the normal Min Trip setting is 560 Amps, circuit was close to tripping on load.
Are the above CLP settings common, as my experience has been to set CLP settings at 2x peak load current to avoid load trips?
