Re: [CAD_CAM_EDM_DRO] 3-Phase motor running from Single Phase Supply ?

I'd have to see the actual motor to be sure, but as I recall from my
military eletrical training, some motors were provided with taps to provide
dual voltage use. This works something like transformers with multiple taps
for multiple voltage outputs. In this case only part of the windings would
be used when operating on 240V.

Smoke
-----Original Message-----
From: Dick Ganderton <dick@...>
To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
Date: Sunday, December 31, 2000 10:20 AM
Subject: Re: [CAD_CAM_EDM_DRO] 3-Phase motor running from Single Phase
Supply ?

>Older motors were often permanently connected in star. The star point was
>burried inside the windings. Modern motors usually have all the six ends
>connected to the terminal board in such a manner that a simple ling change
>will connect it either in star (for 414V), or delta (for 240V). 414V
>3-phase is the prefered industrial supply in the UK, so most industrial
>motors run star connected.
>
>Perhaps the clue with your Bridgeport motor lies in the word
>"dual-voltage". Bridgeport must have some magic way of getting the 414V
>star connected motor to run with the same power on 240V!
>
>
>>> On Sat, 30 Dec 2000, Dick Ganderton wrote:
>>> > I am using a 2.2kW invertor to convert from 240V single phase to 240V
>>> > 3-phase. Gives me variable speed and other 'goodies' like acceleration

and

>>> > decceleration, remote control, etc.
>>> >
>>> > Disadvantages are that you have to be able to connect the motors for

delta

>>> > instead of star and this is not always possible, or easy to achieve,

on

>>> > older motors.
>>
>>Hmmm? Why is that? It can be proven electrically that a delta-connected
>>motor is indistinguishable from a Wye-connected one, without opening
>>it up and looking. (Thevenin's theorem.) So, is this wiring change only
>>to change motor voltage, or what?
>>
>>I am using a VFD to drive a Bridgeport dual-voltage motor, and it is set

up

>>for Wye only, as the center of one of the wye windings is inaccessible.
>>My inverter seems to like it fine.
>>
>>Jon
>>
>>
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>
>
>Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems, for CAD, CAM, EDM, and DRO.

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