Subject: Re: Converting 3-pahse VAX Power.
To: None <port-vax@NetBSD.ORG>
From: None <cjn@isd.se>
List: port-vax
Date: 03/29/1996 08:22:50
> Ja, ja. Just a little common sense and a bit of electronics
> background is all you need. Put in single phase fans and the mod will
> work. Exactly where/how to do it on a 86X0 (or a 88X0 for
> that matter) I have no idea , I'm not very familiar with
> those machines. Goodness knows what line current one of those ECL
> machines will draw using single phase power , I would make sure the
> cables are ADEQUATELY rated ! This of course is the REAL reason for
> using a multiple phase supply on such a machine (not just to run the
> fans and make your life difficult). It reduces considerably the line
> current , and in doing so allows cables of reasonable cross section
> to be used , obviating problems with voltage drops over long cables ,
> etc. Also , the ripple at the output of the 3-phase rectifier of
> higher frequency than that obtainable with a single phase rectifier
> (you have 3 voltage (or current) cycles per 360 degrees) , so you can
> get away with smaller smoothing caps also.
The 86x0 require huge amounts of electricity, 30 A a phase if I
recall myself right (The powerconnector on my machine is about 3.5cm
in diameter that would be about 1.3") And changing the fans would be
a horrible project since they are kind of mounted in the bottom of
the machine, wich means that you have to strip it all down (You dont
turn a 86x0 upside down... ;-)
But i guess thats all hypothetical since anybody with enough
airconditioned space to house probably got a three phase connector
aswell (or can afford to install one)..
/Chris