Synchronizing DG Sets

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ramvinod Guru Join Date: Jun 2007 Location: chennai,India Posts: 592 Good Answers: 19	Synchronizing DG Sets 04/27/2009 12:01 PM
	Dear all We have peculiar problem in one of the installations in chennai,India. There are two DG sets 10kV,2000 kVA with Mitshubishi engine and kato alternators. These two sets are to be operated in parallel. The control panel has been provided with Woodward EGCP 3 controller. The star point of the alternators are earthed thru neutral grounding resistor.The neutral grounding panel has been provided with isolator. The system is designed to open the neutral isolator when both sets are made to operate in parallel.Each DG set has been provided with Potential transformer of ratio 10/root3/110/root for instruments and EGCP sensing. We are in a position to synchronise the sets.The load sharing is fine. When ever we open one of the neutral isolators,after parallelingThe Potential transformer fails.(one phase of the PT failed) We are unable to ascertain the reason? Valuable suggestions/input are welcome to solve this problem. We have sofar replaced three Potential transformer __________________ Ramesh,Freelance Electrical/automation Consultant
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sivamugunthan Member Join Date: Nov 2008 Location: Frankfurt Posts: 6	#1 Re: Synchronizing DG Sets 04/28/2009 7:14 AM
	I am keen to suggest you provided you send me the following information NGR capacity of each Alternator what's the operating mechanism for NGR panel ( opening) After paralleling which NGR is going to be online Thanks and Regards S.MUGUNTHAN
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ramvinod Guru Join Date: Jun 2007 Location: chennai,India Posts: 592 Good Answers: 19	#3 In reply to #1 Re: Synchronizing DG Sets 04/28/2009 11:19 AM
	Dear Sir, Thanks for your contribution.As desired I am furnishing the following information: The NGR capacity is 63.5 ohms,10kV,200 A,10 sec. NGR is cut off by Mototr operated Isolator.For closing and opening of the Isolator motor operated mechanism is used. After parelling the Master DG which was closed first,has to be ON and the neutral isolator of the second one (slave) has to be switched off. Hope to get some more inputs from you. ramesh __________________ Ramesh,Freelance Electrical/automation Consultant
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harry potter Power-User Join Date: Nov 2008 Location: India Posts: 333 Good Answers: 6	#2 Re: Synchronizing DG Sets 04/28/2009 10:24 AM
	Dear, I have come across similar problems with other distribution class PTs also. There, it was concluded that the star point of PTs seconday was not properly grounded. Due to this, floating neutral caused the high voltages, damaging PT coils. Same may happen to you. Try with PT common to be grounded directly to earth. by passing NGR only for PTs. In any case, whatever DG may be master or slave, PT common shall always be grounded for both the DGs. This may solve your problem. __________________ Exploring the Science of Electricity
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ramvinod Guru Join Date: Jun 2007 Location: chennai,India Posts: 592 Good Answers: 19	#4 In reply to #2 Re: Synchronizing DG Sets 04/28/2009 11:23 AM
	Dear sir Thank you for your suggestion and we will check and try this and revert back. ramesh __________________ Ramesh,Freelance Electrical/automation Consultant
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Anonymous Poster	#5 Re: Synchronizing DG Sets 07/03/2009 3:22 AM
	Dear Sir I Am Sebastian From Bangalore. Now I Am Doing Synchronizing Work For BEL Chennai. 2X500 KVA & 1X125 KVA DG Sets With Woodward EGCP-2 Relay. For More Information: You Can Call Me +91-9900-453-791 OR Login to our website: http://www.s4sindia.hpage.com E-Mail: sebastian.solution4system@aol.in
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Anonymous Poster (1); harry potter (1); ramvinod (2); sivamugunthan (1)

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