365 Main reason for outage report published

Deepak Jain deepak at ai.net
Fri Aug 3 18:59:34 UTC 2007

> Register4Less recently reported a power failure in Montreal where the
> return of a single cycle from the utility tricked generators into
> shutting down all three cycles, throwing the data center onto UPS until
> the batteries died.  They did not report make of generator or of the
> board that failed them.

Many generator control systems (and transfer switches) do not monitor 
all three phases for voltage, and stability (phase sync). Any of these 
can cause a UPS to use its batteries (without charging) and not fire up 
the generator. Or conversely, allow a generator to power down.

Its happened to lots of people in various places, but I am not going to 


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