Substation Breaker Relay Settings Calculations
Substation Breaker Relay Settings Calculations
(OP)
In setting a breaker relay (ABB DPU 2000r) for the 51p element our relay is set for a ickup of 5 with a 600:5 ct ratio, this means at 600 amps the relay will pickup and operate. The time dial is 1. On the 51p-1 element the pickup is set at 7.3, what is the calculation for this element's pickup, is it the 7.3 times the ct ratio or is there another factor involved?
Our 51N element is 1.2 and time dial of 6. I assume that this will start picking up at 1.2 times ct ratio, with a tardiness of 6 based on the time dial. Is this correct?
Then the 51N-1 element has a pickup of 20, so does this calculation go 20 times the ct ratio also?
Our 51N element is 1.2 and time dial of 6. I assume that this will start picking up at 1.2 times ct ratio, with a tardiness of 6 based on the time dial. Is this correct?
Then the 51N-1 element has a pickup of 20, so does this calculation go 20 times the ct ratio also?






RE: Substation Breaker Relay Settings Calculations
RE: Substation Breaker Relay Settings Calculations
RE: Substation Breaker Relay Settings Calculations
RE: Substation Breaker Relay Settings Calculations
RE: Substation Breaker Relay Settings Calculations
RE: Substation Breaker Relay Settings Calculations
I stand by my previous posts. DPU2000R, DPU2000, Circuit Shield DPU all work this way. Take a look at WinECP, and you'll see the 50 element settings are called "pickup X." The X means your entry is not in secondary amps, but a multiple of the time overcurrent setting. Testing also confirms this. You may also wish to RTFM and review your settings. http
RE: Substation Breaker Relay Settings Calculations
Switchgearman are you sure about your calculation on the 50P-1 set for 7.3 amps, I have a relay that fault data shows the 50P-1 element didn't operate at 3600 amps. I thought the 7.3 was a multiple of the 51P.
RE: Substation Breaker Relay Settings Calculations
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Read through the manual especially on pg 2.
Regards
Ralph
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