Wacky Weekend: NERC to relax power grid frequency strictures

Sun Jun 26 21:43:57 UTC 2011

> 2) Allowing transformer fields to collapse. Even in phase, without a 
> delayed transition ATS you can end up with a partially collapsed 
> transformer field with a new field being created at non-ground state. 
> This can cause a transient back wave that can snap circuit breakers. 
> Yep, this one happened to us a few times before we switched to a delayed 
> ATS, was a PITA to debug and resolve.

a transformer should be switched to the network when phase is at
highest/lowest point, not at zero.
zero: highist current
highest/lowest point: lowest current
because it's a coil.

Kind regards,
 	Ingo Flaschberger