Boxford 280 T. electrical fault

[Tony Burdett]

I have converted this lathe with the help of members to run on 240v about 5
years ago and it’s run fine ever since but after using it all morning I
switched it on this pm and blew the RCD .I now can’t use the start switch or
12v light to run it but by jamming the contactor in I can run it by means of
the multi speed switch I fitted at conversion. I have tested the transformer,
there is 240v input but no 12v or 110v output, before I invest in a new
transformer is there any thing I may have not considered, is it not uncommon
for a transfer to fail and are there any cheaper 250 v>110 >12v transformers
out there than a Boxford one.
https://www.polytechforum.com/img/77

[David Billington]

On 04/05/2021 22:18, Tony Burdett wrote:
> I have converted this lathe with the help of members to run on 240v
> about 5

> years ago and it’s run fine ever since but after using it all morning I
> switched it on this pm and blew the RCD .I now can’t use the start

> switch or
> 12v light to run it but by jamming the contactor in I can run it by
> means of
> the multi speed switch I fitted at conversion. I have tested the
> transformer,
> there is 240v input but no 12v or 110v output, before I invest in a new
> transformer is there any thing I may have not considered, is it not
> uncommon
> for a transfer to fail and are there any cheaper 250 v>110 >12v 
> transformers
> out there than a Boxford one.
> https://www.polytechforum.com/img/77
>
>

I don't know that lathe but have a few machine tools with varying
voltages for different applications such as main motor, feed motor etc.
I've seen transformers fail and a pain if they're odd sized and fit in a
tight enclosure with little chance of an off the shelf replacement. What
is the 110V and 12V used for, you've indicated the 12V may be for the
light, what is the 110V used for? You could probably just use a 240V to
110V transformer and a separate 240V to 12V transformer both suitably
rated for the load.

[chris]

On 05/04/21 22:18, Tony Burdett wrote:
> I have converted this lathe with the help of members to run on 240v about 5

> years ago and it’s run fine ever since but after using it all morning I
> switched it on this pm and blew the RCD .I now can’t use the start

> switch or
> 12v light to run it but by jamming the contactor in I can run it by
> means of
> the multi speed switch I fitted at conversion. I have tested the
> transformer,
> there is 240v input but no 12v or 110v output, before I invest in a new
> transformer is there any thing I may have not considered, is it not
> uncommon
> for a transfer to fail and are there any cheaper 250 v>110 >12v
> transformers
> out there than a Boxford one.
> https://www.polytechforum.com/img/77
>
>

If the rcd has tripped, it suggests leakage in the motor windings or
other powered item to ground. You need to isolate both and use a
megger or solid state equivalent, to check for leakage from any
winding to frame. Quite common for insulation to fail an older
motors.

Assume this is a single phase motor ?. I rebuilt a Boxford A a few years
back. Put in a 3 ph 2hp motor and vfd. Kept all the original pulleys
and set the vfd for 25 to 75Hz o/p. Reason for the 2hp motor is that
power goes down quite a it at 25Hz drive. Great range of speeds
though...

Regards,

Chris

[David Billington]

The OP mentioned he could run the motor by manually actuating the
contactor so not the RCD. RCDs can go bad, mine started tripping
whenever I turned on my TIG welder so I had the TIG welder tested and it
was perfect so had the RCD tested and it was bad and got replaced. The
electrician advised using the test switch on the RCD at least every 3
months to exercise it, a mate recently replaced his and the sheet with
it said once a month.

[chris]

Perhaps he can run it, but it's not safe to do so until the failure
reason is known. RCD's are there for a reason and bypass them at your
own risk. Foolish thing to do, especially in what may be a damp workshop
environment...

Chris