Closed Transition Return to Normal

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thanksinadvance Associate Join Date: Mar 2010 Posts: 33 Good Answers: 2	Closed Transition Return to Normal 04/22/2010 3:32 PM
	Electrical System: (3) 2000kW Gen sets located on floor 1, (4) networked 2500kVA transformers on the basement. The Generators and service entrance transformers feed the emergency equipment via an ATS on the 8th floor. My question is to transfer the power from commercial to emergency I use an open transition to supply the load, but on return to commercial I want a closed transition from Generators to Commercial. I want to use the woodward GCP-31 governor for my gen's. To complete the closed transistion I must sync the generators that are supplying emergency power to the available commercial power. Now since the ATS are located on the 8th floor do I install CT's and PT's at the service entrance switchgear and have those talk to the woodward or should I do all this sync'n at the ATS. There is considerable distance between the ATS's and the service entrance gear and the voltage at the service entrance gear vs. the voltage at the ATS under load could be dramatically different. It seems resonable to do this - a closed transition on the return to normal at the 8th floor ATS, but so far I am the only ones who think so... The ATS is 3000A and there are 8 of them too. __________________ guest
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msamad Guru Join Date: Feb 2009 Location: Houston, USA Posts: 946 Good Answers: 244	#1 Re: Closed Transition Return to Normal 04/22/2010 6:58 PM
	If you install the CT's and PT's at the service entrance switchgear and have them wired to the Woodward GCP-31 governor, it should be ok. You also need the wiring between the GCP-31 and the ATS to send the close/open command to ATS and receive the status the ATS status. There might be one concern about the voltage drop in the cable along the length between commercial service entrance and the ATS. The Woodward GCP-31 will sense the voltage from the service entrance and the generator terminal but due to the voltage drop, there will be a difference between the two systems at ATS. If the voltage drop is within the tolerance of the synchronization, then it should work without problem. See this link for more detail for Woodward GCP-31 governor: http://www.precisioncontrols.co.uk/assets/downloads/woodward-lr/gcp-30-series-user-manual.pdf I am not an expert of Woodward GCP-31. So, I would suggest you to contact both Woodward and ATS before doing it. - MS __________________ "All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
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