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Potters Wheel, conversion from DC to AC and upgrade

I am a potter and have a 40 yr. old potters wheel driven by a DC motor which has reached the end of its life. I have a replacement AC motor which I wish to fit. The wiring is both ancient, Black & Red plus earth, and is set up for DC. The power is fed in via a domestic three pin plug.

The on/off switch is old and temperamental as well as the on and off function it also has a circuit breaker – which further complicates the wiring. The on/off switch is connected to a speed controller which is also original and the wires to the motor attach by a multi pin plug – which is perished. The company who manufactured it is no longer trading.

The long and short of it, is that I think a root and branch transplant is needed!

My thoughts are to replace the on/off switch with an RS Pro non fused panel mounted unit and to replace the controller with a modern electronic fan speed controller. The existing unit has a small gear cog which connects with a quadrant cog connected by a rod to a foot peddle. The housing,  cog and connecting system are all in good order and can be reused. Wiring wise I hope to use water proof 3 core cable I have in stock.

All the electrics are housed within the wooden cabinet of the wheel, and although the water side of operations is separate ingress cannot be completely ruled out.

Any comments and advice is very welcome.

I plan to do the set-up myself and then have it checked by an electrician.

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Comments

March 30, 2020 09:14

Hi, interesting and sounds like a timely project!
Not a solution but areas to think about.
First the new AC motor, my first thought is the normal shaft speed at full speed suitable? What fraction of full speed will it be at in normal use, it can be quite difficult to run the motor at substantially lower speeds.
This brings me to the fan controller, has it adequate power ratings for the new motor?
Many AC motors have a cooling fan built-in on the shaft, the cooling efficiency drops as the speed is reduced so there is the question as to whether there will still be adequate loading.
Also, how does the fan controller control the speed? The best methods are variable frequency controllers, but I have only used these on 3phase motors where they work very well.
Regarding construction, I would consider having all the mains related items, speed control and circuit breaker in an external box away from any water. I would look to have the switch ideally control a low voltage on/off feature on the speed controller for safety and also go for a suitable IP rating to ensure water is kept out and it can be washed down.
The only mains power in the "wooden box" would then be to the motor and via a suitable IP junction box. The motor and all metal parts should then be earthed,
Just some thoughts for consideration, I have not considered the speed control from the foot pedal as I can't visualise the current arrangement. There will be other points to consider but I hope this gives some areas to consider to progress.

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