Motors and Motor Circuits Protection

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jinxnao Power-User Join Date: Mar 2007 Posts: 310	Motors and Motor Circuits Protection 02/01/2010 9:27 AM
	hello, pls show me with a simple motor protection including its circuit, when we use a motor protection relay (with protection features???), it means we protect the motor from short and overcurrent, but what about the motor circuit protection? do we coordinate line ampacity, fuse (of motor circuit relay ) rating and motor load or use a second protection device for the line?? __________________ jinxnao
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RDGRNR Guru Join Date: Dec 2009 Location: San Antonio, TX USA Posts: 844 Good Answers: 29	#1 Re: Motors and Motor Circuits Protection 02/01/2010 11:31 AM
	Here's a simple circuit. Try www.electrician2.com for calculation formulas. __________________ "Do not worry about your difficulties in Mathematics. I can assure you mine are still greater". - Albert Einstein
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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	#2 Re: Motors and Motor Circuits Protection 02/01/2010 11:34 AM
	The fuses protect the wiring. In the event of a short-circuit, these operate, disconnecting the circuit. The motor overcurrent protection device operates to protect the motor. Making sure these two operate in the correct way is called co-ordination. Does that help? __________________ "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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Anonymous Poster	#3 Re: Motors and Motor Circuits Protection 02/02/2010 1:56 AM
	Dear Mr. jinxnao First, Please tell us the application of Motor load. Decide the complete specification of motor. then as per the criticality of protection required, whether a simple microprocessor based OLR is required or motor protection relay. There are lot of manufacturers in this world like Siemens,ABB,Schneider etc which manufacturers MPR. Please check with the manufacturers for the same. The MPR comes with various options
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Anonymous Poster (1); PWSlack (1); RDGRNR (1)

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