ATS Won't Transfer

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thanksinadvance Associate Join Date: Mar 2010 Posts: 33 Good Answers: 2	ATS Won't Transfer 03/09/2010 10:28 AM
	I currnetly have a square D ATS and I am almost positive it is a 3 pole 480v. The problem lies when I kill utility power the Gens fire up and and the ATS switches and life is good, but when Utility comes back the Transfer switch won't transfer back instead the open transisition starts to transfer then it stops halfway through and I have no power to my load, so I lost the data center. I am visiting the site next week I need a good plan of attack. Could it possibly be a ground fault located somewhere preventing the return to utility? Circulating currents on the ground? Square D ATS are crap (Square D service techs have nothing) Anybody experience anything like this? __________________ guest
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#1 Re: ATS Won't Transfer 03/09/2010 1:12 PM
	The first problem is that Sq. D doesn't really *make* transfer switches. They *sell* them as parts of a piece of gear, but they buy products from someone else. So sometimes it is Asco, sometimes it's Kohler, sometimes Russell, etc. etc. I recently saw that their parent company, Schneider, bought some Chinese mfr who makes cheap residential ATS', so it that's what you have, heaven help you. Usually it stems from a problem with the sensing devices. For the ATS to transfer back, it has to "know" that the utility supply is back and correct. It relies on a protection relay or has a sensing circuit that determines this. if anything is incorrect, it failsafe: i.e. no re-connect. Start there. __________________ All I every really wanted to be, was... A LUMBERJACK!.
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Haajee Guru Join Date: Feb 2006 Posts: 1758 Good Answers: 6	#2 In reply to #1 Re: ATS Won't Transfer 03/10/2010 4:00 AM
	Regards. A good Answer but I may have the privilege to add: ATS should also sense the Synchronizing of bothh supplies. It is a MUST. In case of manufacturers: All manufacturers of OEMs do not manufacture all components & Assemblies themselves but use most of those either from OFF-THE-SHELF* or from different manufacturers if some custom design requirements exists. This is only true for Major manufacturers. * small industries.
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Anonymous Poster	#3 Re: ATS Won't Transfer 03/10/2010 11:01 AM
	I was leaning toward the synchronization of the main grid with the genset as well. There should be a failsafe built in that will not allow you to bring the main on with the genset without the two dynamos being in sync, usually with the genset leading just a bit so that the grid won't start running the genset before you take it off the line and resume normal operation off the grid. Or, it could be just a crappy ATS. We had one that was also a Square D that would not hold the load. Four tech reps standing around scratching their heads when in walks a guy with a can of WD-40 and sprays the hell out of it, and presto, it worked fine.
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