ATS Overlapping Neutral vs Switched

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highriser

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In the midst of an ATS replacement or retrofit (ASCO 940 - to something else). This 940 has an overlapping neutral. Question has come up - if we replace do we stick with an overlapping neutral or go to switched. Seen several opinions on the general question - including from GE - saying the overlapping neutral doesn't provide a real benefit. But, then I see that ABB (which took over GE's switches) is selling switches with overlapping neutrals at a premium (ZTS series).
 

highriser

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Interesting read, I knew the reasoning behind the overlapping neutral, but GE’s engineers say it’s a none issue.
As long as the switched neutral is break-last/make-first, and there aren't large regenerative loads - which leads me to ask if their non-overlapping neutral switches are still break-last/make first, and what regenerative load is considered large.
 

zooby

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Since I believe ASCO had the first patent on overlapping neutrals, they have white papers that are pro-overlap.

I think the data is significantly obscure, and we choose overlap if the manufacturer offers it (which some do not), and switched if it isn't offered by the vendor.

Nice link! When I saw "white paper" I thought why bother? It'll be wayyyy over my head. That is a good read. Thanks Ron
 
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