Hello,
It has been a while since our wheel stopped functioning. It was fixed last week.
The schematic diagram mentioned in the previous posts is not quite the same as ours.
I have attached our diagram.
The issue we had is that the protection switch kicked in after a few turns of the wheel.
It turned out that the cause of this was a failed capacitor in the field circuit. This capacitor shorted out, causing a resistor to burn and a fuse to blow.
Even without field current there is some remanent magnetic field, and the armature could still turn. However, because the field is weak, the armature current was high. This caused the tripping of the safety breaker.
We replaced all capacitors, the burnt resistor and replaced the fuse. The wheel works fine now.
Ben
speed control pottery wheel forum.pdf