"Christopher Tidy" wrote in message
...


Jerry Martes wrote:
"Christopher Tidy" wrote in message
...

Still thinking about a phase convertor...

I've just seen this transformer on eBay which is rated at 10 kVA. It says
the primary is rated at 240 - 480 V and the secondary at 120 - 240 V. Do
you think this might be suitable for a phase convertor if used in
reverse? Perhaps there is some way to reduce the voltage slightly before
feeding it to the idler motor, or perhaps the motors would stand 480 V?
We don't get the full 240 V from our supply anyway.

Here is the link:

http://cgi.ebay.co.uk/10kva-Transfor...cm dZViewItem

Chris


Chris

The single phase 10 KVA transformer looks like it can be wired to take
240 vac up to 480 vac. Transformers dont mind being reverse connected,
as you probably know, even though the primary is conventially wound
closest to the core. The eBay transformer would be a good choice for
your need to use a 480 vac idler to make 480 vac 3 phase from a 240 vac
power source..

Thanks for the advice. Out of curiousity, why is the primary traditionally
wound closest to the core? This transformer is tempting, but my concern is
that the "official" voltage in the UK is 415 V, so I will be supplying a
somewhat excessive voltage to the motors. What do you think?

I asume that you are more comfortable with 480 vac than I am. I hate
480.

I'm pretty careful. I only ever once had a shock, and that was off a
capacitor which had held a charge for a while. After that I was very wary
of capacitors.

Chris

Chris

The only reason I know about for winding the primary close to the core is
to give it maximum capability to couple to the magnet core. That would
ninimize the losses even while no load is applied (idling time)

The ratio of IN to OUT voltage as determined by the jumpers on the eBay
transformer is the imprtant factor for you. Can you put 208 VAC single
phase into the eBay transformer?

There is a problem with 480 other than electric shock. 480 has the
ability to vaporize metals and spray it around. I have seen the results of
dropping things across 480 and I'm probably overly 'scared of it.

Jerry