REF - Restricted Earth Fault Protection

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kasrop Associate Join Date: Nov 2016 Posts: 38	REF - Restricted Earth Fault Protection 08/15/2018 10:13 AM
	Dear all when REF (Restricted earth fault protection) for power transformer operated we check the transformer it is ok then we check the CT polarity also ok. please what are the possible causes for operated REF (Restricted earth fault protection) thanks for all
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: REF - Restricted earth fault protection 08/15/2018 10:45 AM
	Was the wiring connected to the transformer checked as well? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#2 Re: REF - Restricted Earth Fault Protection 08/15/2018 11:35 AM
	..."Restricted earth fault protection provides earth fault protection for the secondary side of the transformer and the cables/busbars up to the incoming terminals of the LV incoming circuit breaker. This type of fault occurs upstream of the incoming circuit breaker and therefore can only be disconnected by the MV circuit breaker on the primary side of the transformer."... http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/321000/FA321225/en_US/technical_bulletin18_v4%20Restrited%20Earth%20Fault.pdf __________________ All living things seek to control their own destiny....this is the purpose of life
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PeterT Guru Join Date: May 2010 Location: Liverpool, NY Posts: 961 Good Answers: 131	#3 Re: REF - Restricted Earth Fault Protection 08/15/2018 4:06 PM
	You gave very little information for us to make even a guess at your problem. And since we can't see your transformer and your system, we can't figure it out for ourselves. It would be helpful to answer the following: 1. Was the transformer operating normally for a period of time, or did this happen when it was first turned on (new)? 2. Has this happened before, and if so, what was found then? 3. What disturbances on the primary feed to the transformer were known or recorded? Was there any change in the system, both primary and secondary? 4. Was any new work done on the system prior to this event happening? 5. A single-line drawing of the system would help, including showing the REF relay connection and any other protective relays. 6. Did any other relays indicate any fault? 7. What specific investigation and testing was done to prove that "the transformer is ok"? 8. What testing was done on the relay to prove that it operated properly? And I could go on. You should hire a competent testing firm to investigate this for you. We cannot do it for you remotely. __________________ To get the right answers, first you need to ask the right questions.
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