3 Phase Motor question


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8 Aug 2019
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I have a nice WEC 3 phase motor circa 1998 which says on the plate that it's 400V - no mention of 240. However when I took the cover off the connection box the terminals and wires are exactly as I would expect to find in a dual voltage motor. There are 6 wires going into the motor and they're laid out in the normal way connected by bars. The layout of the wires is identical to the dual voltage layout (u1 is opposite w2 etc) and there are even 3 connection bars in the box where only 2 are necessary for the existing wiring.

I suspect that it is a dual voltage motor - which suits me just fine because that's what I need, but does anyone know of a way to verify this?

Has anyone come across this before? I can see why a manufacturer might make all their motors dual voltage but label some as single voltage, after all the data on the plate is correct for the wiring as supplied.

Very common to find motors that are dual voltage only specify one voltage.
To see if it’s a 220/400 or a 400/700v motor look at how it’s connected at the moment. If it’s connected in Delta, you’ve lucked out. The motor is a 700 star, 400 delta motor. If it’s connected in star, happy days, the chances are it’s a 220 delta, 400 star motor. Not definitive as it may have been ‘tampered’ with the connections. If it runs properly, full power on delta connected to 400V it is a 200/400v motor.
Ace - that's what I suspected, as is it's connected star and was previously running at 400v. I'm certain it's unmolested as it's original on a lathe that was bought new by a school.

With a lathe it will I believe be a small motor, so it’s almost certain to be 220/400. It’s generally only the large KW motors that are 400/700 for star delta starting.