Round-dial 10EE overload relay and field winding problem

perky2 · Jan 26, 2022

Ok, its been a few years since I restored this lathe and i forgot much of what i knew. Lathe started going wonky. Tripped breaker in dc panel. I reset it and it would run for about thirty seconds then kick out again. Started getting worse and would not reset. Would run if I manually press contact in. Then got really weird and when i tried to change speed would stop and go in reverse without touching anything else and forward contact stayed engaged. Turned on motor generator today and it smoked the breaker.Where can I get a new breaker? Any help would be much appreciated. Unfortunately I am not an electrical wizard. Thank you.

Cal Haines · Jan 26, 2022

That overload relay won't cause the symptoms that you're describing; it's the canary in the coal mine. You have some other problem that's overloading the DC panel. It might be a short in the field of either the spindle motor or the generator or perhaps a short in the generator rheostat. What do you mean by "the lathe started going wonky"? What exactly was going on when the problem first happened?

If someone doesn't have a spare overload relay, it can be replaced with a fuse. (The square-dial DC panel uses a 1A fuse instead of an overload device for the same circuit.) If you do find a spare, know that you have to move the heater from the old relay to the new one. The heater is the oddly shaped metal strip, located below the reset button and mounted with two screws. The heater is what controls the current level that trips the relay.

Cal

perky2 · Jan 27, 2022

It was running fine till it started tripping the breaker. I let it sit overnight and it would run for maybe 5 minutes then would trip the breaker. I checked all the brushes and they all seem to be making contact. Checked for loose connections and did not find any.The stopping and going in reverse is what I meant by going wonky.When the breaker tripped and would not reset I manually pushed the contact closed and the spindle motor would run. When I tried changing speeds it would change rpm if I turned the speed control slowly. If I tried changing speeds quicker it would stop and go in reverse just like you flipped the headstock lever to reverse without changing anything so I would quickly shut it down to prevent any damage. I actually have not run this much since I restored it but it always ran fine. The motor generator seems to run fine. Is there a way I could check the voltage coming into the breaker without killing myself or if you could walk me through some troubleshooting I would be grateful. If there is any information you need let me know and I will get it to you. Thank you

perky2 · Jan 27, 2022

Its not brush timing,I checked all the brushes and holders for problems. I know how to set timing with equal speed in forward and reverse. If I manually close the contactor it will run. When I change the speed is when things go haywire. I have only tried running it for a few seconds. I dont want to do anymore damage so I thought I would ask for help. I know you and Cal know these machines like the back of your hand. I dont have a schematic or the electrical knowledge to go poking around on my own so I thought I would ask for help. Thank you

perky2 · Jan 27, 2022

That may well be the case. The first time this breaker kicked out on me I started tugging on wires in the dc panel looking for loose connections or any bare spots. It ran ok for a while after that. I really would like to diagnose and fix this before I do anymore damage. This was a US navy machine with the original drivetrain all intact and funtioning. Thank you

Cal Haines · Jan 27, 2022

First of all, this is not a circuit breaker, so let's stop calling it that. It's an overload relay. The typical AC circuit breaker is a two-terminal device that functions as a resettable fuse, both sensing and interrupting the current through the device. An overload relay is a four-terminal device: two terminals are used to sense the load current; two terminals are used to control something. If the two halves are wired in series, it can function like a circuit breaker, but that's not how they are typically used.

On this model DC control panel, one overload relay senses the current to the DC panel and everything that it feeds, including the fields of the generator and spindle motor, as well the big Ohmite rheostats. When that one operates, it kills power to the entire DC panel. The second overload relay senses the armature current and interrupts the forward/reverse relay control circuit, shutting down the spindle motor and generator.

The overload relay in question is probably the one that protects the DC panel. If that's the case, when you forced the main contactor closed, you forced the armature circuit to run, but without the spindle motor's field. When that is done, the spindle motor can rapidly run away and all sorts of strange/bad things can happen. In the future, never do that again; it's right up there with putting a penny in a fuse box. You probably have a short or perhaps a rheostat problem that's overloading the DC panel.

I'll have to do some digging to find the spindle motor and generator resistance tests; maybe I can do that this evening. In the meantime, I want you to do two quick tests to verify the identity of the overload relay:

Set your Ohmmeter on it's lowest range, usually 200 Ohms
Tests are done with the machine shut off.
Check for continuity between terminals E1 and E1-2 at the bottom of the DC panel. Use the metal tags on the wires to verify that you're on the correct terminals.
Check for continuity between terminals C3 and E2.

Cal

perky2 · Jan 27, 2022

Oh, believe me , I am old enough,64, to know I am way out of my element. I am very good at mechanical things when I can see how it is supposed to work.I have tried many times over the years to understand electricity and I just can not get a grasp on it. I can not see what it is doing so I can not diagnose what is wrong because I don't know what it is suppose to be doing. I don't know if that makes any sense to anybody but that's how I see it. I would be grateful for any tips on how and what to check.

Cal Haines · Jan 27, 2022

perky2 said:
... I would be grateful for any tips on how and what to check.

44 mg dc panel need help post #8

perky2 · Jan 27, 2022

Oveload relay it is. Continuity check on e-1 to e-1-2 has continuity,8.7 on meter. c-3 to e-2 has continuity, .3 on meter.

perky2 · Jan 28, 2022

perky2 said:
Oveload relay it is. Continuity check on e-1 to e-1-2 has continuity,8.7 on meter. c-3 to e-2 has continuity, .3 on meter.

I found a schematic close to mine. I should not have gotten continuity on one of those with the overload relay removed should I?

Cal Haines · Jan 28, 2022

What you're seeing is the resistance of the exciter's series field in combination with the spindle motor's field and some of the other stuff on the DC panel. But 9 Ohms is a lot lower than I would expect for that. Disconnect E1-2 at the bottom of the DC panel and it should read open.

Send me an e-mail and I send you my color coded version of the schematic for your machine.

Cal

Cal Haines · Jan 28, 2022

It will be at least tomorrow before I can pull together the resistance tests for you. (I have about 300 pages of saved posts to search through.)

Cal

perky2 · Jan 28, 2022

Cal Haines said:
It will be at least tomorrow before I can pull together the resistance tests for you. (I have about 300 pages of saved posts to search through.)

Cal

I really appreciate you taking time to help. If there is something I can do in return let me know. All my pictures and old posts from my restore must be gone, I can't find them.

Cal Haines · Jan 28, 2022

I found three of your previous threads, complete with photos, under the username perky:

reliance 3hp motor question
reliance motor problems
45 mg 10ee

In the last one, four years ago, you were reporting a problem with the DC panel overload relay and it doesn't look like it was resolved then.

Look in the first thread. I give directions for spindle motor resistance checks, start there.

Cal

perky2 · Jan 29, 2022

Cal Haines said:
I found three of your previous threads, complete with photos, under the username perky:
reliance 3hp motor question
reliance motor problems
45 mg 10ee

In the last one, four years ago, you were reporting a problem with the DC panel overload relay and it doesn't look like it was resolved then.

Look in the first thread. I give directions for spindle motor resistance checks, start there.

Cal

Did the tests. a1 to a2 3.0. f1 to f2 5.5. The other ones where open. I put a 2 amp fuse where the relay was and it blows the fuse as soon as I start the motor generator. I must have lost my password at some point and reregistered. Thanks. Apparently after rereading my old posts I was having the same problem back then and never fixed it. I have not touched the lathe since then. I restored a couple cars and built a cnc plasma table since then and just never got back to it. Did you know your memory starts to fade as you get older?

Cal Haines · Jan 30, 2022

perky2 said:
Did the tests. a1 to a2 3.0. f1 to f2 5.5. The other ones where open. I put a 2 amp fuse where the relay was and it blows the fuse as soon as I start the motor generator. ...

That's not good. You should see about 70 Ohms from F1 to F2. 5.5 Ohms suggests that three of the four field coils are toast and the fourth has an internal short.

Based on your earlier posts, it seems that the machine had a lot of electrical problems when you got it:

perky said:
... After cleaning the mouse nests out of the M-G i put power to it and hit the switch. Much to my surprise it fired right up. So i let the M-G run for about 5 minutes and it sounded fine. Turned the speed control all the way down and hit the lever and again the spindle runs. Now my question is i touched the paper insulation on one of the motor main field windings and it just crumbled. ...

perky said:
ok I finally got around to rewraping my field coils with # 27 3m tape and glyptol . Motor worked fine when i took it out. Insulation was half gone on field coils. On the bench i was reading 73 ohms at f1 and f2 and infinite on other poles. Put the motor in and i have bad brush sparking and motor only runs in reverse at slow speed. Now my readings are 54.6 ohms on f1 and f2 . A1 to f1 is 1.7 ohms and 1.6 at a1 to f2 . ...

You had a short between the armature (probably the interpole coils) and the field, but I don't see what, if anything, you did to correct the problem. (For the record, the motor should have never been put under power with a reading that suggests a short between the armature and the field.)

The motor needs to come apart that the resistances of the individual coils needs to be checked. Each coil should also be checked with "megger" to determine the condition of the insulation, but I'm not hopeful. You'll probably need to have the coils rewound. Look around for a motor shop that's willing to rewind the coils for you (vs. doing a full rewind job on the motor), that can save you money. But a lot of shops don't want to deal with old motors and will give you a sky high price. My local motor shop might be able to help you if you strike out locally.

You should also reach out to PaulM in Massachusetts and see if he still has the motor that he offered you (link).

Cal

perky2 · Jan 30, 2022

Cal Haines said:
That's not good. You should see about 70 Ohms from F1 to F2. 5.5 Ohms suggests that three of the four field coils are toast and the fourth has an internal short.

Based on your earlier posts, it seems that the machine had a lot of electrical problems when you got it:

You had a short between the armature (probably the interpole coils) and the field, but I don't see what, if anything, you did to correct the problem. (For the record, the motor should have never been put under power with a reading that suggests a short between the armature and the field.)

The motor needs to come apart that the resistances of the individual coils needs to be checked. Each coil should also be checked with "megger" to determine the condition of the insulation, but I'm not hopeful. You'll probably need to have the coils rewound. Look around for a motor shop that's willing to rewind the coils for you (vs. doing a full rewind job on the motor), that can save you money. But a lot of shops don't want to deal with old motors and will give you a sky high price. My local motor shop might be able to help you if you strike out locally.

You should also reach out to PaulM in Massachusetts and see if he still has the motor that he offered you (link).

Cal

Yeah that seems strange because when the motor did run it ran fine right up to 2200 rpm.

Mr_CNC_guy · Jan 30, 2022

One easy thing to check is the commutator. Each of the segments of the commutator
should have equal amounts of arcing at their edge. If there is significantly more
arcing evident on some segments than others then you likely have a shorted turn in
the armiture. I don't think that is your principle problem here but you should
check it while you are in there.

perky2 · Jan 30, 2022

thermite said:
That motor will do a LOT of "normal appearing" things, even when rather badly crippled...

... so long as there is no LOAD on it.

The "specfied" 2500 RPM IS a loaded figure, BTW. I get 3,300 no-load at the output shaft on a well-tuned and healthy motor at max Field weakening.

I "tune" brushes for about 800-900 RPM at nominal max field. unloaded vs the 690 "base" RPM, on the dataplate, as that. too, is a "loaded" figure, and at 230 VDC, not the higher Voltages "available" when called for.

So 2200 RPM, unloaded, was not optimal.

Two of my motors came from PaulM. One - a 3 HP "small frame" Reliance, has moved-on, is powering another PM member's 10EE out West. Another - a 3 HP "large frame" Reliance survived potentially destructive testing, still runs fine.

Paul had more "back then"

I don't know if he still does, but there are others out there from part-outs (rare) or VFD downgrades (too damned common!) .

If they seem expensive?

BRAND NEW even CLOSE to the same "Type T" steam-turbine smooth performance, Reliance publishes a MSRP of about twelve THOUSAND US dollars.

Rewind of the complex lays of the coils can easily go above $2,000. IF one can even find Old Skewl motor shops familiar with DC lift/elevator, hoist & derrick goods.. coz those are the higher-volume industries where these motors originated.

If you can acquire another 10EE motor for $300 to $ 500, I would recommend it.

They are SOOOO rugged, problems of the sort you are seeing are exceptionally rare, so getting two "impaired" ones in a row is unlikely.

For really stable load regulation with rather basic controls, Monarch used them loaded at but 25% to 50% of their hard capability limit.

Run that lightly loaded - or even LESS - most all their lives, they "just keep on working".

Yeah , hence the problem. Finding somebody competent today? Thats why I'm here. I am pretty sure you guys are my best bet. Everybody today is a parts changer if they can even find the part on the computer. I would like to backtrack and get the relay to stop tripping before I condemn the drive motor.

Cal Haines · Jan 31, 2022

perky2 said:
... I would like to backtrack and get the relay to stop tripping before I condemn the drive motor.

The overload relay was tripping because it was OVERLOADED!!! Your field windings are shot. Fix the motor or get another motor. There was nothing wrong with the relay.

Cal

Round-dial 10EE overload relay and field winding problem

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