Relay/Contactor ????'s

[customcutter]

Replace the transformer today. The original was wired 110v input with 24v output 100VA. The replacement is 120V input 25.6v output 2amps, so +/-50VA. The original transformer burnt up when it was wired to 240v (see other posts).

Everything works up to the point of starting the lathe. It starts and runs for about 3 seconds, then the relay releases and it stops.

The lathe has 3 relays/contactors (not sure of the correct name), 2 C16G's and 1 C11G. The C16G have 10 contacts, plus one at the base that is 24v. The C11G activates when I turn the machine on. When I push the start button, the left C16G relay activates for about 3 seconds and drops out. All 3 relays have a push to test button. If I push the test button on the left relay it runs as long as I keep it depressed. If I push the C16G on the right it runs in the opposite direction until I release it. There are no controls on the front of the machine to reverse spindle direction??? There is a control to reverse the lead screw. Would it also reverse the spindle at the same time?

My main question is what is causing the relay, contactor, coil, solinoid whatever it is called to drop out after 3-5 seconds? Does it have a primary/secondary winding and the primary is pulling it in and then the secondary is "bad" causing it to drop, when the primary releases?

Do you think the transformer is too small, and doesn't have enough current to operate everything? I've got a 20amp VariAC that I could temporary up test if necessary?

Any thoughts or suggestions are appreciated.

thanks,
Ken

[becksmachine]

Doesn't seem like the transformer is too small.

There should be some overload protection somewhere (heaters), these need to be sized for the amperage draw, which increases/decreases when changing the voltage.

Are you moving a lever at the apron to start and stop the spindle? If so, try moving this lever the other way and see if maybe the spindle doesn't turn in the opposite direction. This is in addition to the leadscrew reverse.

Dave

[MaxHeadRoom]

As Dave mentioned, you need to know what else is in the coil circuit, it well could be O/L contacts of some sort, usually fitted to the bottom of the contactor and in series with the coil circuit.?
Max.

[customcutter]

Dave:

Yes, the heater was tripped from the original over voltage. I reset it, it tripped again and I increased it from 18 to about 20. It reads from 12-18 on the dial. The dial reads RC-AMP on the front? The heater is not tripping any more.

Ken

[Don Young]

It sounds like the machine might have recently been converted from 240V to 120V. If the overloads were not changed or adjusted, the increased current would cause them to open and drop out the motor relay.

There is surely some sort of spindle reverse switch on the lathe unless it has been removed or changed.

If the transformer does not overheat it is large enough.

[lakeside53]

What are the plate ratings on the motor?

[customcutter]

Are you moving a lever at the apron to start and stop the spindle? If so, try moving this lever the other way and see if maybe the spindle doesn't turn in the opposite direction. This is in addition to the leadscrew reverse.

Dave

Dave:

I tried moving the handle on the apron, SUCCESS! kind of. Apparently the handle was in a "bad" location. I thought it was in neutral, but where ever it was it had the relay messed up.

The lathe continues to run. It switched from forward to reverse spindle directions. However, I left in forward for a minute or so to make sure it wasn't going to drop out. Tried to shut it down and it would not shut down.

I finally had to unplug it. The contacts are welded in on the left (forward) relay.

So how to I unstick the relay. I tried tapping on it no success.

thanks,
Ken

[customcutter]

It sounds like the machine might have recently been converted from 240V to 120V. If the overloads were not changed or adjusted, the increased current would cause them to open and drop out the motor relay.

There is surely some sort of spindle reverse switch on the lathe unless it has been removed or changed.

If the transformer does not overheat it is large enough.

Yes, I think it must have been. That was part of the original problem, 220v plug so I wired it 220v, but apparently it is 110v.

Didn't realize the lead screw handle was a switch , but finally found it thanks to Dave.

The transformer is running cool.

thanks,
Ken

[customcutter]

What are the plate ratings on the motor?

2 HP, 220/110v, 1 phase, 1720rpm, 4 pole, 60Hz.

thanks,
Ken

[lakeside53]

Are the current ratings on the plate? That will tell you if your overload trip is within range.

Personally... at 2hp I'd run that lathe on 240 volts.