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From: ron@brl-tgr.ARPA (Ron Natalie <ron>)
Newsgroups: net.periphs,net.news.sa
Subject: Re: uninteruptable power supply for a VAX
Message-ID: <11237@brl-tgr.ARPA>
Date: Thu, 6-Jun-85 17:23:38 EDT
Article-I.D.: brl-tgr.11237
Posted: Thu Jun  6 17:23:38 1985
Date-Received: Sat, 8-Jun-85 02:14:43 EDT
References: <1218@cbosgd.UUCP>
Organization: Ballistic Research Lab
Lines: 30
Xref: watmath net.periphs:783 net.news.sa:118


> The CPU has a funny round plug which is described to me
> as "single phase, 20 amp, 120V", which sounds like an ordinary
That connecter, known to the Natioal Electronics Manufacturers
organization as an L5-20, is an attempt to keep you from plugging
it into an inadequate circuit.  This is the locking variety (keeps
it from becoming unplugged) of the 5-20 which looks like a normal
plug.  You could change it to a 20A regular plug.

That was for a 750 by the way, 780's use L21-30 which is three phase.
Actually, there is no 3 phase in there, but 3 phase 30A is a lot easier
to come buy in a lot of places than what you'd need in single phase
power to run the entire VAX.  

> circuit with lots of capacity - I don't understand why the funny
> plug at all.  The tape drive (TE16) and one of the disks (RM05)
> have their own special plugs, too.

The disk drive takes an L6-20.  This is 208Volts not 120, do not change
the plugs.  The tape drive uses an L5-30, this is 30A service.

> Has anyone figured a reasonable way to keep such a machine running
> through a typical one second power hit from a thunderstorm?  What
> do you do?  Has anyone concluded it can't be done or is a bad idea?

Short of full blown UPS (expensive) we just use a power distribution
unit which catches the transients and other environmental nasties and
nicely shuts the power off to everything.

-Ron