Wadkin BRA 350 RAS capacitor wiring

[JamesH]

I have a bit of a problem with a refurbished wadkin BRA 350 radial arm saw I've just bought on ebay.
The motor wont turn when switched on, it just makes a humming noise. It will only start up if the blade is spun before switching on.
Part of the refurbishment was the installation of new wiring, and I'm convinced that the capacitor has been incorrectly wired, given the nature of the problem.
Currently, the blue wires from the motor and start switch along with an earth cable are connected to one terminal of the capacitor and the brown wires from the motor and start switch are connected to the other terminal.
I'm not an electrician but to me it seems that the capacitor is bypassed.
Does anyone here know how the wires should be connected on this particular machine?
Numerous emails to wadkin have gone unanswered - they just don't want to know.

Any advice would be greatly appreciated.

 

[CHJ]

Instruction Manual with wiring diagram PDF.

Unfortunately it does not go so far as showing connecting cable to motor and termination at motor.

 

[tomatwark]

Hi James

I would get a sparky to look at it for you.

I guess it is a 3 phase machine.

Wadkin will probably not be able to help in any case as it depends on if the machine is DC braked or not, the machine has been wired into a remote stop button at some point or made to operate an extractor on startup and are you running it through a phase converter all these things can make a difference.

Just because it has been rewired does not mean it will work with your set up as the seller may just have copied the existing setup and replaced the wires.

It is probably just a case of swapping a few connections around and a way you will go.

Tom

 

[JamesH]

CHJ, I have that manual, but as you say it doesn't go into a great deal of detail. Thank you all the same.

tomatwark, it's a single phase 240v machine, unbraked.
I hope it's just a simple matter of swapping connections rather than the capacitor or worse the motor.

Is it a permanent capacitor run motor? It doesn't have a centrifugal switch and there is only the one capacitor. Also the capacitor is quite a large, heavy box type located under the table of the machine.

James

 

[JamesH]

Would anyone be able to post any photos of the capacitor, start switch and motor terminal connections on their machines?
I may be able to work it out from there.

James

 

[JamesH]

Does anyone else here on the forum own a 240v wadkin BRA350 radial arm saw?

 

[Myfordman]

Wadkin quite often use an external starter. Look for a relay designed to switch in the capacitor during starting.

 

[JamesH]

The original external starter box has been replaced and there's no relay to be seen anywhere in the circuit. Should there be one?
I'm guessing the motor is an induction capacitor start/run type? There are no brushes or a centrifugal switch within the motor to cut out the capacitor.

 

[Myfordman]

Hi James,
Although I have never worked on a Wadkin BRA, I am surprised that it does not have either a centrifugal switch or a relay type starter.
Do you think that it is possible that whoever fitted a new starter did not understand that sensing relay starters were used and just fitted a modern NVR, found it did not work and sold it on ebay?

The wiring you describe above sounds strange so can you draw out a circuit of what you have and post it please.
Some photos would be helpful too.
Also do you have a meter capable of measuring resistance down to a few ohms and know how to use it? This would help me give you instructions of how to proceed.