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Transformer in reverse

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Joules:
Sounds much more sensible using it as an autotransformer.  I don't really understand how you're going to power your VFD with only equivalent of 2 phases though, surely it will just flag an error.  It's dark now so will watch for the flash on the horizon   :zap:


Be careful.

awemawson:
Joules, most VFD's take in three phase and rectify to some DC voltage using a three phase bridge rectifier. If you apply single phase 400  between two phase inputs then you still get the DC rail established, you just have to de-rate the VFD a bit.

The Gotcha is that some, but not many, VFD's have 'phase failure detectors' embodied that will fail out if you do this. You're fine in most cases though and I've done it many times reliably.

Joules:
Cheers Andrew, didn't know that.

philf:

--- Quote from: John Rudd on December 13, 2015, 12:20:59 PM ---Thanks for the advice guys....

I have a 3ph inverter that obviously needs a 415ac supply, if I can generate 415v single phase then I should be able to test it.... :zap:

I have a test rig that comprises a light bulb in series with the Live leg, then a switch, then a 13A socket, using my variac ( 500w rated) I can gradually wind the juice up using the lamp bulb as a current limiter....ok back to it.... :bugeye:  :zap:

--- End quote ---

John,

There was some discussion a while back on modifying a 415v input 3 phase VFD to run on 240v single phase. Have a look in this thread:

http://madmodder.net/index.php/topic,10679.msg123558.html#msg123558

I successfully converted an ABB VFD which is now happily powering my Fobco Seven-Eight drill.

Phil.

John Rudd:
Andrew,
Good idea about the tranny windings....I should have thought of that in the first instance.... :doh:

I'll give that a try...need to find the transformer out first....hidden in a pile of other stuff.

I'm limiting my chances of something going  :zap: all of the plugs have 3A fuses in them... :lol: and my nerves dont like big bangs...

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