Re: How much current safe for 30m extension?

From: Peter Bennett (peterbb_at_somewhere.invalid)
Date: 02/13/05 

Date: Sat, 12 Feb 2005 19:47:33 -0800

On Sat, 12 Feb 2005 11:08:03 -0800, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

>
>"Sammo" <noone@no-where.com> wrote in message
>news:95FB7BA1F25441A7D4@130.133.1.4...
>> I am in the UK (so mains voltage is about 230V or 240V).
>
>I'm in the U.S. and this gives me a flashback on what I was thinking
>about trying a few months ago. We have a PBX at work that's on 48V
>batteries, but the batteries are 9 yrs old and need replacing. They
>cost a bundle so I thought it would be possible to run a power cable
>underground to the big UPS we have in our computer room. Problem is
>that the PBX's rectifier takes 30A max at 120VAC, or about 3.6kW. And
>the distance between is about 1300 feet or about 400m.
>
>I would guess that the UPS output should go into a transformer and come
>out 480VAC, so the cable losses would be minimized. Then another transf
>on the PBX end to bring it back to 120VAC. But should I expect to have
>a max loss of 5% at max current, or what? I think I came up with 4GA
>cable, but at 480VAC, I'm guessing that it would have to be special
>insulated underground cable.

If you're going to use transformers at each end of the link, you can
make one of them tapped, so you can select an appropriate tap to
compensate for the voltage loss in the cable. 

-- 
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

Relevant Pages

  • Re: How much current safe for 30m extension?
    ... >I would guess that the UPS output should go into a transformer and come ... new newsgroup users info: http://vancouver-webpages.com/nnq ... Vancouver Power Squadron: http://vancouver.powersquadron.ca ...
    (sci.electronics.components)
  • Re: Combining dual secondaries of a toroidal transformer
    ... transformer (one an electronics tech would install inside equipment) ... The best way, regardless of the transformer marking or colour code, is ... new newsgroup users info: http://vancouver-webpages.com/nnq ...
    (sci.electronics.basics)
  • Re: Calculating DC Output Current From Unregulated AC Transformer
    ... Transformer is rated for 12VAC, ... bridge rectifier and capacitor after it easily enough but how does one ... Vancouver Power Squadron: http://vancouver.powersquadron.ca ...
    (sci.electronics.basics)
  • Re: Sizing circuit breaker and cables
    ... mounted sockets and a breaker to protect the transformer. ... I know it has to do with power factor but this ... new newsgroup users info: http://vancouver-webpages.com/nnq ...
    (sci.electronics.design)