I have just bought a 3 phase Boxford STS and would like to convert it to single
phase by fitting a single phase motor ,is it possible to use any of the existing
switching . Regards Tony email@example.com
I have just looked at the data plate on this Boxford T 280 and found that it
looks as if it is a dual voltage Brooks motor 380v- 450 v / 220- 240v so I need
to find out how to wire it for 240v and if the various switches are compatible .
You've found that you have a dual voltage motor which is good but won't
help you run it off single phase very much. The motor will run off 415V
3 phase when in Y configuration or 240V 3 phase in delta configuration.
These days you will find you can likely buy a new single phase to 3
phase inverter for a similar cost to a new single phase motor, maybe
cheaper, and you can get the benefit of variable speed if required.
Earlier on in the year I bought a package from
with a 1hp motor and inverter and the
likely use the current switches with an inverter but would need to wire
them as direction inputs to the inverter rather than swapping phases as
inverters don't like having their outputs disconnected under load from
what I have read, or the ABB inverter I used just had a direction switch
on the control panel. The motor in the package I bought was 415V/240V
and had to be changed to 240V for the inverter operation as it converted
240V single phase to 240V 3 phase.
I strongly recommend the inverter route in which case all the switch
functions are dealt with by the inverter.
The existing stop and start button can possibly be re-used but the
internals are of no use in this application.
I fitted a Jaguar inverter and 3 phase motor my STS 10-20. I made my own co
ntrol unit which fits on the front of the lathe, but buying the inverter ma
nufacturers pendant or control unit may be a simpler option. The existing p
anel switches could be used for inverter control suitably rewired plus the
addition of low voltage relay, and variable speed pot instead of a separate
control unit. I retained the use of the front panel start & stop switches
which operate the internal contactor powering the inverter but that's proba
bly overkill. Changewheel cover switch and foot stopswitch are also wired i
nto the inverter control circuit. The single phase coolant pump wiring is u
nchanged and still operated from the front panel switch. Variable speed inv
erter operation makes the machine so much more flexible and would definitel
y be the preferred option.
I bought one about 5 years ago and successfully converted to single phase using
existing switch gear and contractors as the main contractor is 230v it was a
matter of rewiring the contractor to suit this operation. The lovely thing with
a single phase induction motor is to reverse is you require the reversing switch
to reverse the start winding/capacitor. I managed the buy a good but cheap
second hand 1hp from online auction site and made up a new mounting adaptor with
a replacement drive belt. Let me know of you need any further details.
Thanks for the reply Doug.I eventually went down the inverter route, I had
originally thought that inverters were still the big rotary affaires but
following advice from this site I bought a digital one for under £100 ,this
allowed variable speed control via a potentiometer and forward and reverse. Do
you have an original manual for your Boxford ? Kind regards Tony