Re: Converter or Inverter for 2hp Bridgeport mill

David, you should remove the overload relay between the VFD and
motor. If it should ever open, the transients could damage the VFD.
As a rule of thumb, you should not have any type of switches between
VFD and motor unless special considerations are in place to stop the
VFD before opening the switch.

~petev

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ibewgypsie"
<ibewgypsie@h...> wrote:

> I used a toshiba single phase in, 3 phase out inverter. I used the
> bridgeport relay to turn on with dry contacts, left the overload in
> place (overkill since inverter monitors too). I gutted the cnc

drives

> and upgraded at that time too thou. Inverter works great.
>
> My phase convertor made the head rattle, inverter is much smoother.
> Money well spent. I have my machine on a 30 amp 220 single phase
> circuit now. Like I said I upgraded the cnc drives too. The 3 phase
> cnc drive transformer had to go.
>
> David Cofer
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "john_glynn57"
> <john_glynn57@y...> wrote:
> > I have just taken delivery of my own Bridgeport mill and want to
> > know which is the best option for powering the machine : an

inverter

> > or a converter.
> > My research to date suggests that a Hitachi L100 inverter is the

way

> > to go however I want to question this as follows:
> > 1. I can run a dedicated 20A or 30A supply to the machine which
> > should be able to handle the startup current demand of a

converter.

> > 2. If I use a converter I can use all the original Bridgeport
> > systems without mosification ie Bridgeport speed control,forward

and

> > reverse,3phase coolant pump and shaping unit which is attached to
> > the machine.
> >
> > My plan is to circumvent the original Bridgeport wiring and drive
> > the Main motor(s) directly from the hitachi unit and setting the
> > motor speed at the low speed of 1400 and not using the valiable
> > speed control of the machine at all. The hitachi will give me

speed

> > control by varying the frequency however I do intend to use the
> > original forward reverse switch. In addition I plan to replace

the

> > coolant motor with a single phase model.
> >
> > Am I doing the right thing.