relay coordiation

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Anonymous Poster	relay coordiation 02/25/2011 5:27 AM
	what is mean relay coordiation
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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: relay coordiation 02/25/2011 6:06 AM
	British Standard 7671. __________________ "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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RDGRNR Guru Join Date: Dec 2009 Location: San Antonio, TX USA Posts: 844 Good Answers: 29	#2 Re: relay coordiation 02/25/2011 8:11 AM
	__________________ "Do not worry about your difficulties in Mathematics. I can assure you mine are still greater". - Albert Einstein
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67model Guru Join Date: Dec 2010 Posts: 1686 Good Answers: 116	#3 Re: relay coordiation 02/25/2011 11:29 AM
	Coordination between relays used for protection usually refers to the desirable action that a fault is always disconnected by the device immediately upstream of the faulty load. Disconnection by a device closer to the supply, which will also disconnect other loads which are working normally is not desired. This requires (ideally) that the settings and operate time versus current curves of relays, [with allowance for tolerances from dial/plug settings and the behaviour of current transformers] are such that down-stream devices operate before up-stream devices for all possible fault locations. Sometimes, the "worst possible" fault at a downstream position can exceed the maximum breaking capacity of its local protection. In this case, upstream protection may be required to operate faster than local protection for currents exceeding local breaking capacity. Also, in case 4., the local protection device may be rated to carry, but not break the highest fault current for the operate time of its upstream protection [to ensure that it was still suitable for continued use after the fault]. In that case, the ratings are coordinated as well as the relay/in-built operate time.
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Coldspot Power-User Join Date: Apr 2010 Location: Where no man should ever live Posts: 195 Good Answers: 6	#6 In reply to #3 Re: relay coordiation 02/26/2011 7:40 AM
	I think it is great when people write and consolidate concepts - and sometimes get hammered for doing so - and when I do so I better understand the principle. GA from me. __________________ Who is so ignorant as not to know that knights-errant are beyond all jurisdiction, their only law their swords, while their charter is their mettle and their will is their decrees? Don Quixote
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rakesh_semwal Guru Join Date: Oct 2006 Location: India, 200 Km. North of Delhi. Posts: 1393 Good Answers: 53	#4 Re: relay coordination 02/25/2011 11:53 AM
	There are two types of relay coordinations in general. 1 Operating two or more electric relays in a systematic manner to achieve certain objective. 2 Click here for type two of relay coordination.
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ramvinod Guru Join Date: Jun 2007 Location: chennai,India Posts: 592 Good Answers: 19	#5 Re: relay coordiation 02/26/2011 12:47 AM
	Please see this link: __________________ Ramesh,Freelance Electrical/automation Consultant
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Anonymous Poster	#7 Re: relay coordiation 02/26/2011 11:08 AM
	Next question from the OP will be "why doesn't the fan stop when I turn the bathroom light off". Where in "what is mean relay coordiation" does fault level discrimination get a mention? The OP hasn't given enough information (as usual)
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