Wacky Weekend: NERC to relax power grid frequency strictures

Jay Ashworth jra at baylink.com
Sun Jun 26 16:07:08 UTC 2011

----- Original Message -----
> From: "Michael DeMan" <nanog at deman.com>

> It is my understanding also that most commercial grade gensets have
> built into the ATS logic that when utility power comesback online,
> that the transfer back to utility power is coordinated with the ATS
> driving the generator until both frequency and phases are within a
> user specified range?

I don't believe that's actually true, Mike.  In a *load transfer* 
configuration, it's really not all that critical if the power presented 
to the load skips phase a touch on the transfer; there's a 50-500ms gap
in the power anyway, since such transfer switches are required by the
NEC to be non-shorting, so they don't electrocute power workers.

-- jra
Jay R. Ashworth                  Baylink                       jra at baylink.com
Designer                     The Things I Think                       RFC 2100
Ashworth & Associates     http://baylink.pitas.com         2000 Land Rover DII
St Petersburg FL USA      http://photo.imageinc.us             +1 727 647 1274

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