Re: Bridgeport 440 volts to 220 volts.

Jeff,

Thanks for the reply.
I am starting to think it might be easier to replace the switch.
Mine has the high/low switch plus it has the emergency stop switch.
Bridgeport manual says the heaters are in the switch box and are
very hard to get at. I have looked and you can not see the typical
coil type overload heaters.

Thanks

Gary

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "washcomp" <jeff@w...> wrote:
> Gary:
>
> The motor starter is sometimes called the contactor. It is
> sometimes combined with a safety switch (combination starter).
The
> three things you look for:
>
> 1) The heaters (overloads) will be pretty ovbious to any
> electrician with motor experience. If you contact the
manufacturer
> of the starter, they can help you locate the heaters. Depending
on
> the vintage of the starter, they may look like a losenge with a
> number on them or may look like a spring. They will break the
coil
> circuit if they are overloaded.
>
> 2) Check the coil voltage of the starter. If your tool uses high
> voltage control, the coil may be 440v and have to be changed.
>
> 3) Check the current rating of the starter. The motor will draw
> about twice as much current at the lower voltage. Since starters
> are sized by current, if yours was marginal at 440 volts, you may
> need to change the starter.
>
> Regards,
> Jeff
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "cncgramps"
<cncgramps@y...>
> wrote:
> > --- 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