I think I have a burned out relay

What kind of machine are we dealing with here?
Post a picture of the tag on your motor.
I see your in Michigan. I probably have a good used contactor with overloads.......if you pay for shipping
Cincinnati 2ML

Main motor
main.jpg

Overarm motor
overarm.jpg
Do you know the history of the machine? If it's a 3 phase machine it's likely it could be wired either 220V or 440V. If it was originally wired 440 and is now running on 220 it's likely the overloads (heaters) are too small. I had a similar problem with a Bridgeport. It was originally run on 440 and later changed over to 220. It would run a few minutes, or sometimes only a few seconds then quit. A little investigation found whoever changed over the wiring hadn't replaced the overloads. At 220V the overloads were undersized and couldn't handle the current.

I would also check the coils for the contactors. If they're 440 coils they likely won't pull in or hold the contactors when run on 220 volts.
It was originally wired for 440. I rewired for 220. I am unsure if the machine even has heaters as it looks like they have all been jumped. I believe this is the case with the overarm.

Take the wires off the coil. Wire in a pigtail that you can plug into a wall to energize the coil with the coil energized use your meter to check the far right set of contacts on the motor starter. These appear to be the latch circuit. A latch circuit is what holds the contactor on when the on push button is not depressed.
I have already done this and the coil seems to lock up solidly.
 
I will be unable to make it back out to the shop until Friday so it's going to be a couple of days.

As I said before, I am not adverse to updating the circuits to something a bit more modern. At this point would that be a good option?
 
Stop this!

Wrong things being suggested, rather wrong process.

Do NO corrective action as it is intermittent and you need to measure things to determine fault.

When working or not working measure major points or if not sure print a few copies of photos and with your voltmeter measure voltage on every terminal.

Circuit is very simple.

Power routed through a normal open push button (start) to the coil of the contactor.

Other side to return or neutral.

Power also to contactor line connections and an extra for latching.

This output is usually routed back to the coil via the heaters (circuit breaker like devices) and a normally closed push button (Stop switch), when normal this line holds the contactor closed, if any of them open then coil releases.

Measure and confirm voltages along these lines, does holding the start button stop the chatter?

Yes then latch line

No then contactor

Make corrective action only when you find an issue then treasure to confirm your repair was correct.

This is really easy if you take your time.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
It is not intermittent as he has the same result everytime he tries to start the machine.
If someone doesn't have a good understanding of electricity and how to troubleshoot with a meter then suggesting that they work on a live circuit with an unknown meter and leads and without them knowing exactly where they are going to be probing with those leads doesn't sound good or like it will achieve quick or accurate results.
Instead deenergize the panel and start using an ohm meter with your drawing in hand.
You will START to learn and understand the circuits and will probably find the issue without possibly being shocked.
 
I have looked over the posts from the git-go, I couldn't find for sure where I got the impression. So I ask point blank if the machine is being run from single phase power. I see the photos of the motor, three phase. If so, it is quite possible that control power is being drawn from the "synthetic" third phase. Whether using a Rotary Phase Converter, a capacitor bank, or a VFD really doesn't matter. If one side of the control power is coming from that synthetic third phase, it will be, at best, unstable at the start. It will smooth out some as the motor comes up to speed, but still not as it should be. Follow that through and make sure that control power is from the two leads where power is solid under all circumstances.
The coil of the starter is in bad shape. It should be replaced, whatever the circumstances. If I were at work (been a while) the entire starter would be changed out. Having only two overload heaters dates the starter from long ago. They have had three for as long as I can remember. For machine tools, the third is superflous but is the norm today. It might be more cost effective to find a Chinese made starter rather than trying for a coil and two heaters.

The "insight" came from sleeping on the problem. Having been out of the electrical field for ten years plus, my mind is not what it once was. But look into where control power comes from, make sure it is from the line, not the third, synthetic line.

.
 
It is not intermittent as he has the same result everytime he tries to start the machine.
If someone doesn't have a good understanding of electricity and how to troubleshoot with a meter then suggesting that they work on a live circuit with an unknown meter and leads and without them knowing exactly where they are going to be probing with those leads doesn't sound good or like it will achieve quick or accurate results.
Instead deenergize the panel and start using an ohm meter with your drawing in hand.
You will START to learn and understand the circuits and will probably find the issue without possibly being shocked.
No, it is intermittent and seems (seat of the pants) to follow load.

In reply to sd, I am fairly familiar with circuits and am "comfortable" working with live circuits. I am just not all that familiar with control circuits.
 
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I have looked over the posts from the git-go, I couldn't find for sure where I got the impression. So I ask point blank if the machine is being run from single phase power. I see the photos of the motor, three phase. If so, it is quite possible that control power is being drawn from the "synthetic" third phase. Whether using a Rotary Phase Converter, a capacitor bank, or a VFD really doesn't matter. If one side of the control power is coming from that synthetic third phase, it will be, at best, unstable at the start. It will smooth out some as the motor comes up to speed, but still not as it should be. Follow that through and make sure that control power is from the two leads where power is solid under all circumstances.
The coil of the starter is in bad shape. It should be replaced, whatever the circumstances. If I were at work (been a while) the entire starter would be changed out. Having only two overload heaters dates the starter from long ago. They have had three for as long as I can remember. For machine tools, the third is superflous but is the norm today. It might be more cost effective to find a Chinese made starter rather than trying for a coil and two heaters.

The "insight" came from sleeping on the problem. Having been out of the electrical field for ten years plus, my mind is not what it once was. But look into where control power comes from, make sure it is from the line, not the third, synthetic line.

.
I have an RPC. The transformer is not connected to the generated leg.
 
The controls, or at least the coil looks to be Allen Bradley. Hopefully you have a complete circuit diagram with a parts list. If not you can download them from the Allen Bradley website. Heaters and coils of this vintage are plentiful and cheap on eBay. Depending on the model coil you have they are available in the $10.00 to $20.00 range. There are also several contactors available in the same price range. Heaters (overloads) are in the $3.00 to $.500 range.

I have several machines with similar controls. It's far cheaper and far less labor to replace the faulty parts than convert to newer style controls. If you're considering repairing the current controls this is an excellent time to buy the needed parts, and maybe even a few spares. My machines with AB controls date from 1955 to 1982. They all have the original components except for the coils and heaters that had to be changed on the machines originally wired for 440V.

I have one lathe with Furnas controls. They are far more expensive than Allen Bradley. The contactors on this machine are getting worn. Rather than try to find replacement parts for this system I purchased a complete NOS panel with reversing starters, coils, heaters, etc., etc. for less than $100.00. When/if the time comes to make the change I should be able to replace the entire unit in an afternoon. The best part is I'll be able to use the original controls, including the gear motor that allows infinite changes of spindle speed.
 
No, it is intermittent and seems (seat of the pants) to follow load.

In reply to sd, I am fairly familiar with circuits and am "comfortable" working with live circuits. I am just not all that familiar with control circuits.
So the intention isn't to offend anyone but, OSHA pretty much made virtually all working on live circuits a violation about 15 years ago and that was in a trained professional environment.
Do people still do it? Sure, that doesn't make it a good idea.
Not having worked with a person I don't know their skill level, I rarely advise working on live circuits.
When the OSHA rulings came about I worked on virtually every thing live but the company would not allow that so I realized I could do alot of troubleshooting with the circuits deenergized.
No disrespect to the poster but after 30 years of working with people who said they knew or understood your post shows you don't. Again I mean no disrespect this is from decades of experience that I say this.
I believe you can and will learn this and more but I would prefer it would be without incident.
Obviously the latch circuit is you issue just for the fun of it deenergize the panel and use your ohm meter after some basic test with the ohm meter use a pigtail to energize just the contactor with the wires that were on the coil removed try that ohm meter between the off PB and the latch circuit intersection to the coil through the contacts on the motor starter.
A test of the motor starter coil will give you a value in ohms.
the circuit if good should be very close to that ohm reading if not you can safely touch, wiggle , remove and reattach the wires in the latch circuit until you find the issues.
 
If it was me I'd just replace the contactor, overload heater, switches, and transformer. Rewire the whole thing in the process. You have old heat damaged components, corroded terminals, and jumpered heaters. It'll cost you a bit of money, but if you have some feel for electronics it is relatively easy.

So the only question is with two motors ... do both motors run at the same time? Or is the photos shown of only one motor's control circuitry? *Ideally* the two motors would each have their own overload heater, set for their Full Load Amps (FLA) rating. If both motors run at the same time, you can use one 4 pole contactor rated at combined load, then split the power after the contactor through separate overloads to each motor. The control circuit becomes x----Stop----Run-----OL1-----OL2-----contactor coil-------x
Where x is the two 120v outputs of the transformer,
Stop is just the stop switch
OL1 is the switch contacts on the overload heater to motor 1
OL2 is the switch contacts on the overload heater to motor 2
Run is a little trickier, it is

--RS--
| |
--| |----
| |
--C4--


Basically the run switch (RS) in parallel with the 4th set of contacts on the contactor (C4).

Hopefully in this case C4 doesn't correspond to explosives ;)

Ah well, the html processor eats my spaces on the RS/C4 diagram. Apparently the [PRE] tag doesn't work here. Grr.
 
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