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3 phase circuit breaker on ONE phase genset

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Posted by Ignoramus25901 on December 30, 2004, 9:38 pm
 
I would like to install a circuit breaker on my generator, mostly so
that I can turn off power at will. The generator has its own circuit
breaker, but I cannot "trip" it when I want to, it only trips when
there is a real excess current.

My MEP-017A that I just sold, had a nifty circuit breaker on it that
could be turned on and off.

What I am thinking about is buying a 3 phase, 3 pole circuit breaker
and installing it on my electrical panel

http://igor.chudov.com/tmp/onan/Diesel/panel  

Question.

1. Is this appropriate.

2. What amps should I choose? My generator is rated for 7 kW, that's
about 32 amps. I suppose 30 amps is too low. What about 50 amps. It
won't have any protective job then (the genset will be protected by
its own circuit breaker) and will function as a simple power ON/power
OFF switch.

So, I am leaning towards buying a 3 phase 50A switch on ebay. Any
thoughts?

i

Posted by Rory Johnson on December 31, 2004, 2:55 am
 
You say you are only using one of the phases now.  Why not just use a
"regular" circuit breaker?  The other two phases aren't sending current
anywhere anyway.

Rory


Ignoramus25901 wrote:


Posted by Ignoramus25901 on December 31, 2004, 3:31 am
 wrote:

Well, I have two legs, to begin with. They both need to be switched.

i



Posted by m II on December 31, 2004, 7:05 am
 Ignoramus25901 wrote:


Ask the store about 'Switch Rated' breakers. They are used here for
things like warehouse lighting where there is no other convenient way
of turning the lights on and off.

The guts are a bit sturdier to make up for the increased use.

You may save money by using a single throw double pole disconnect
instead. Mount it so gravity tends to OPEN the switch...regardless of
internal spring. Wire hots on TOP, so when you open the switch, the
blades are disconnected from the power you should already have turned off.

An isolating switch is usually cheaper than a disconnect. It is not
meant to be used to disconnect active loads. Tell them the maximum
amperage you will be dealing with and they can tell you what you need.



mike

--

Getting an education was a bit like a communicable sexual disease. It
made you unsuitable for a lot of jobs and then you had the urge to
pass it on.

Terry Pratchett

Posted by Ignoramus31471 on December 31, 2004, 2:20 pm
 
Thanks. These breakers are relatively inexpensive on ebay. I set my
eyes on

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item862598700

i

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