Anti Plugging relay

Hi all,

The anti plugging relay coil burned up on my 1946 EE. Fortunately I have another in my box of spares.

My question is, what would cause this? Should I be looking for another failure elsewhere?

Thanks,

Jim

Hickory said:

Hi all,

The anti plugging relay coil burned up on my 1946 EE. Fortunately I have another in my box of spares.

My question is, what would cause this? Should I be looking for another failure elsewhere?

Thanks,

Jim

Click to expand...

Is this a square-dial machine? Motor/generator (MG) or WiaD (Works in a Drawer) tube drive machine?

Do you spend a lot of time running it at higher RPMs? What were you doing when the relay failed? Is dynamic braking working?

The coil of the AP (Anti-Plugging) relay sits across the armature of the spindle motor and is designed to take the full armature voltage for extended periods of time. There are several possibilities for the cause of the failure:

• Old age
• Spindle voltage too high coupled with extended use at higher RPMs (above 50% on the speed control). Check the voltage between A1 and A2 when the machine is running well above 50%.
• Failure of the dynamic braking circuit/resistors can cause high voltages to appear across the armature and thus the coil of the AP relay. Repeatedly deceleration from high speed or load would put a lot of stress on the AP relay coil.

Cal

Hickory said:

Hi all,

The anti plugging relay coil burned up on my 1946 EE. Fortunately I have another in my box of spares.

My question is, what would cause this? Should I be looking for another failure elsewhere?

Thanks,

Jim

Click to expand...

Lots of turns of very fine wire + old age @ 72 a failure is to be expected from time to time.

Bill

The lathe is rarely run above 2000 rpm. I'm going to check the voltage, but my first impulse is to blame this on old age. Old age is the cause of many inconveniences,
I'm starting to experience this myself. Thank you for your help.