2/13/2019 7:46 AM | |
Posts: 1 Rating: (0) |
I work for a Water and Power Utility (MARAFIQ) and we have a lot of Siemens Protection relays in our substations. A year ago a new substation was constructed and commissioned by SIEMENS and the issue mentioned in this case belongs to one of the incoming feeders of 34.5 kV substation. Actually there was a three phase short circuit downstream ( on 30-12-2018 at 5:01:18.646 PM see attached Trip Log) in one of our customers substation fed by 34.5 kV feeder emanating from one of our substations. The protection at the customer site operated and cleared the fault by opening there circuit breaker. The relay of the outgoing feeder (7SJ642 for HC05 panel) in our substation also sensed a fault and pick-up but got reset as soon as the fault was cleared by the downstream customer end breaker. Same was the behavior of 7SJ642 relay installed at the incoming feeder (HC01) of our substation for 51,50 51N and 50N functions which also pick-up and got reset. But one unusual thing happened in the 7SJ 642 relay 67(Directional over current) function. It picked up after resetting of the other over current functions and the tripped the breaker as per set time (200 ms). The 67 function is configured to operate in the direction of transformer side and not in the downstream side. The direction of the relay has been already checked for its correct operation. Also during this incident 67 function did not pick during the fault condition and it only started picking up after the fault was cleared by the downstream breaker. There is no chance of power back flow from Customer end. I am attaching the relevant files for your kind review and technical support to analyze the behavior of the relay. Looking forward to receive your feedback as usual. With best regards, ------------------------------------------------------------------------------------------ AttachmentTrip Log- 30-12-2018.pdf (124 Downloads) |
Last edited by: Jen_Moderator at: 2/13/2019 11:15:17 AMNew subject after splitting |
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2/13/2019 7:56 AM | |
Joined: 12/18/2014 Last visit: 9/21/2024 Posts: 33809 Rating: (4200) |
Hello MILYAS, at first welcome to the forum. This is a forum, where users help other users, if they can. If you want contact to Siemens directly, start a Support Request. |
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