[Discuss] Server Room Power

[jack at coats.org (Jack Coats)]

Back in the days of mainframes, 208 3ph was a normal choice.? Especially for
large disk drives (large datawise for back them, today they are just
large physically).

If you are doing mainframe datacenters, yes, 208 3ph is still a
reasonable standard.
And even APCC sells UPSes that deliver that too (as well as several
other vendors).

If you are doing a telco type data center, having 48VDC is a norm.
For years SUN
sold servers with power supplies especially for the telco.? This is
because they had
an SLA to provide service for 8 hours (at a minimum) after power
fails, and the most
reliable way is to run off of batteries all the time.? So the battery
bank was rated
appropriately.? Western Electric built some awesome 48VDC equipment.

Other companies did telco rated equipment too.? It was priced more like mil-spec
equipment because it was considered 'specialty'.? And normally it was higher
reliability designs.

When I helped build a small 20k sqft data center, we put in 3 1MW
diesel generators.
They fed power to a auto-switch unit that then ran power into 2 1MW APCC UPS's.
The UPS's fed two separate power buses (120V 1ph, one bus from each UPS).
We installed two power drop plugs above each rack, with 20A to each
(and twist lock plugs).