[AusNOG] Question about hardware spec for a DC

[Bob Purdon]

On 24/04/2014 12:09 PM, Tony de Francesco wrote:
> Something I did learn from looking at aftermarket auto transfer switches
> is that not all of them can handle two power feeds that are not
> synchronised (whether that is a potential issue for your site of not?).

Even those that do, at least the ones I've seen, will enforce a short 
break during the switch (for good reason).  Usually short enough that 
most PSU's don't complain.

You want your A & B feeds to the rack to be on the same power phase if 
you're using a transfer switch.  Ultimately the A & B feeds will come 
together somewhere (that may be in the facility, or within the city 
power grid), and as a result, they will be in sync.

They can drift out of sync for various amounts of time during various 
failure scenarios though.