Re: Bridgeport 440 volts to 220 volts.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

>
>
> cncgramps wrote:
>
> >I am about to hook up a Bridgeport Series 1 CNC that is wired for
> >440. I have the manuals and it shows and tells how to change to

220

> >which I need to do.
> > The part that I am in question about is the overload heaters

that

> >are in the switch. The manual says they are hard to get at and

that

> >they recommend getting a new switch wired for 220.
> > I looked in the switch box and I can not see the typical heaters.
> >Has anyone ever changed those overload heaters out so as to be

able

> >to run on 220 volts?
> >
> >
> You just have the little 2 x 2 x 4" drum reversing switch on the

motor?

> That has no heaters. The heaters would be in a device called

a "motor

> starter" and usually are mounted right on one of the contactors.

These

> break the control circuit if the heaters get too hot, indicating

the

> motor is drawing too much current on at least one phase. That way,
> they protect the motor from overload, single phase operation or
> internal shorts.
>
> If there are contactors in the motor box, one of them should have
> heaters on it. They may be quite small, like little cartridges

that

> plug in. You will need to change them, as the current draw on 220
> will be twice as high, and will cause the spindle to shut down very
> easily.
>
> Jon

No mine has a large box with a forward reverse "hi/low" switch plus
an emergency switch.
The manual talks about the heaters being in the main switch box for
the motor and being hard to get at. Thus the reason for replacing
the switch.

Gary