Boxford 280 T. electrical fault

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.
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On 04/05/2021 22:18, Tony Burdett wrote:



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.
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On 05/04/21 22:18, Tony Burdett wrote:


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
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On 05/05/2021 00:16, chris wrote:



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.
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On 05/05/21 13:17, David Billington wrote:



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
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