Thread: Intermittent starting problem 1945 10EE MG

i bought one of those eurotherms. it was wrong for the application so i sent it back.

1945 was the very end of round-dial production; as far as I know, the last round-dial was built in July of 1945. Every 1945 round-dial that I've seen thus far has had the same motor/generator set and DC control panel that was used in square-dial 10EEs. Based on the photo of the MG terminal panel that you posted, you don't have a square-dial MG set. That's important because the DC panels are significantly different.

I need to see a good photos of the DC control panel and the terminal panel on the MG. The ones you posted are very low resolution and it's hard to see what's going on.

What is the serial number and build date of the machine?

Regardless of which MG set you have, the AC inputs to the MG are the bottom three terminals on the MG terminal panel. For the third time, what are the voltages between those terminals (T1, T2 and T3), under normal circumstances and when the machine is "bogging"?

Cal

serial 28386
date 7-1945
voltages T1-T2 263v
T2-T3 247v
T1-T3 275V
under normal conditions spindle idle
same when the spindle is turning

i couldn't get the voltages when bogging

i just went out there and started the machine
it bogged the first two times i tried to start it
i got a video of it. PM me your cell and i will send you the video and some better pics

the machine only bogged twice, then started normally
it may only bog when it cold
i couldn't get it to bog again to measure the voltages

Originally Posted by lectrician1

i bought one of those eurotherms. it was wrong for the application so i sent it back.

As said, they are for working with a 4Q 514C-16 Solid State Armature supply. it's about setting high & low limits, sensitivity, stability, ramp rates, and making use of the alarm signals to disable Armature power if Field power is too low, etc.

An MG with DC panel & contactor reversing both retained, OTOH, what has been working- starting with "inline exciter" models where exciter fail was common, has been the relatively crude, but robust Field supply substitutes.

As basic as a full-wave bridge, optionally a transformer, not always even a capacitor for smoothing.

Lot of those running.

Even if not all hit the 115 VDC for full torque, only around 90 VDC instead, they DO seem to operate those sensitive relays reliably.

Originally Posted by lectrician1

serial 28386
date 7-1945
voltages T1-T2 263v
T2-T3 247v
T1-T3 275V
under normal conditions spindle idle
same when the spindle is turning

i couldn't get the voltages when bogging

i just went out there and started the machine
it bogged the first two times i tried to start it
i got a video of it. PM me your cell and i will send you the video and some better pics

the machine only bogged twice, then started normally
it may only bog when it cold
i couldn't get it to bog again to measure the voltages

You'll have to e-mail them to me. PM sent.

Do the voltages sag when the spindle is started?

It looks like the artificial (generated) phase is on L1. You can verify that by checking the voltages from ground: the real phases will be about 120 VAC, the artificial phase will be higher. Assuming that you have the original Cutler-Hammer AC contactor, only two of the three phases pass through the overload heaters, so you normally want the real phases on L1 and L2. (That involves moving a wire on the contactor so that the starting circuit is on the real phases, see this link: 10EE MG Starter Circuit with Cutler-Hammer Contactor - Revised)

We need to find out if the voltage is sagging when the MG slows down. If your meter has a hold feature and can be set to capture the minimum voltage, you might want to set it up after the MG is running, but before you start the spindle the first time. Reading the artificial phase to ground will tell you if it's sagging on startup. If you have a clamp-on ammeter, you should check the phase currents as well.

Your phases aren't very well balanced, so you may need to adjust the run capacitors, especially if odd things happen when the load changes. If the RPC is otherwise well balanced when used with other equipment, you can add additional capacitors to the 10EE, after the AC contactor.

Cal

i sent you some emails
thanks again
Rich

Bogging problem is back.

this time i measured the voltage drops between phases
in the motor/gen terminal box

T1-T3 275v dropped to 220V during bogging 55v Drop
T1-T2 258V dropped to 210V 48v drop when bogging

T2-T3 245V dropped to 240v this phase only dropped 5V during bogging

the wires from the motor starter in the headstock to the generator have been changed recently by a previous owner they are #10awg.

Any help or opinions are greatly appreciated
thanks
Rich

Are there brushes in the motor/generator that need replacing or maintenance?

Originally Posted by lectrician1

the wires from the motor starter in the headstock to the generator have been changed recently by a previous owner they are #10awg.

#10 is good for more than double the nominal load, but how good are his terminations?

Are there brushes in the motor/generator that need replacing or maintenance?

Yes. Both the "main" generator" and the "exciter" generator. The final drive motor has two sets of two as well.

Look for posts on PM with fotos and narrative as to refinishing the commutators, FITTING new brushes, and TIMING the brushes after fitting-in.

Monarch doesn't MAKE them but they know which ones to special-order for their stock. Due to age, it is not realistic to try to ID the proper ones from current maker's catalogues nor which item needs how many of what to make up a full set.

Their pricing is reasonable, and buying from Monarch reduces your risk of waste or hassle.

DAMHIKT, but another vendor's price seemed to be too good to be true. It was.

I got ONE brush instead of Monarch's SET of four!

i checked brushes on spindle motor and generator. I removed the exciter and replaced it with a dc power supply. All brushes looked good with nice contact surfaces. I cleaned up any debris. commutator surfaces look good. No scoring. I little dirty.

You could be having problems with you service, it was really bad for years at my house because of the old infrastructure. Starting motors pulls the lights down etc., that made starting my MG iffy at times, and often pulling the MG down to the point of the machine kicking off. The line voltage was off balance, and became worse when a 110v side was loaded.

Originally Posted by lectrician1

I removed the exciter and replaced it with a dc power supply.

Easy to do, but it isn't a 100% positive move.

Seems the "exciter" was tuned-into the overall MG system to not only provide the Field supply, but also play a role in load regulation. And now it cannot.

IF I were to do that, I'd also "wish to" use TWO DC supplies. One for the Field power- "only". The the other to operate controls, relays, and contactor coils. "Only".

But that is not as easy as it sounds, EITHER.

The FA and anti-plugging relays are mixed-players. Back to square one.

Each generation of 10EE drive systems was engineered, tested, optimized, tested again, field-proven, improved, etc... as a complete system.

Making a change to a whole DIFFERENT system, be it VFD, servo, or Solid-State DC Drive is one thing.

Hybridizing a mix of part old, part new is tougher.

Each person undertaking that loses what Monarch + Reliance / GE / Louis-Allis / early DC Drive Engineering teams contributed as to extensive testing and optimization - has to start-over.

Not that it is a "show stopper". "We" do it often, and chips get made.

Just that for every era of a 10EE's evolution, the system that was shipped was a well-tested "package" already tuned to be the best it could be.

Not the show-stopper here, either, so long as your DC supply has the balls to haul the load.

I'd have figured you've already have checked the incoming AC mains quality, but if not?

That was a good suggestion to do so. Cheap and easy enough, too.

Originally Posted by lectrician1

Bogging problem is back.

this time i measured the voltage drops between phases
in the motor/gen terminal box

T1-T3 275v dropped to 220V during bogging 55v Drop
T1-T2 258V dropped to 210V 48v drop when bogging

T2-T3 245V dropped to 240v this phase only dropped 5V during bogging

the wires from the motor starter in the headstock to the generator have been changed recently by a previous owner they are #10awg.

Any help or opinions are greatly appreciated
thanks
Rich

Are there brushes in the motor/generator that need replacing or maintenance?

OK. This has nothing to do with brushes or relays, etc. Your Rotary Phase Converter (RPC) is the culprit. You may have a wiring issue between the RPC and the Motor/Generator (MG) terminal panel or a problem with the RPC itself. I would start by looking at the run capacitors on the RPC. Either it doesn't have any or they've gone bad. Your real phases are T2 and T3 and they aren't sagging, so the problem is most likely the run caps.

You need to check the current on T1 when the RPC is slowing and compare it to the currents on T1, T2 and T3 when the machine is running normally. I suspect that you'll find that there's a big mismatch.

Cal

thank you for your reply. Just to make sure. My RPC does not slow down. The motor generator is slowing down. I haven't had any problems with the RPC starting any of my other machines. I have another 5hp lathe and a Gorton mastermill. The RPC is a phase-a-matic 15hp. But I will open it up and check it out. How do i check if the caps are good other than looking at them and seeing they are swollen?

Originally Posted by lectrician1

How do i check if the caps are good other than looking at them and seeing they are swollen?

Checking the RPC under similar loads and heavier loads should be good enough to eliminate it as probable cause. Done that already, but "we' didn't know it until it was asked.

As to caps? I have test gear to test caps, but never bother with that for these types.

Over ten years old, i just replace them. It isn't a lot more work nor expense, soon DONE.. and then you know you have another good ten years. Sometimes 20. Usually, anyway.

Here's an old trick..

Can you:

A) fully DARKEN the room the lathe is in?

B) safely position yourself to lay eyeball into the MG area, the motor compartment as power is activated?

C) Safely see if the darkness reveals any glow or arc where it is not meant to be.

Might need a helper? Even two?

Do you own, or can your borrow, even an El Cheapo "non contact" IR thermometer as can detect hot parts?

I did say "safely", yah? Lethal Voltages chase each other about inside a 10EE.

I just had a similar 10ee mg that i sold a couple of months ago and there was no such problem starting.
i do have a couple of those thermometers but there doesn't seem to be any part that is overheating
i had some sparking around the commutator of the spindle motor the other day but it was debris.
I will try the dark room tomorrow

Originally Posted by lectrician1

I just had a similar 10ee mg that i sold a couple of months ago and there was no such problem starting.
i do have a couple of those thermometers but there doesn't seem to be any part that is overheating
i had some sparking around the commutator of the spindle motor the other day but it was debris.
I will try the dark room tomorrow

Debris? What kind, and from where? Was there damage to that motor, previous home? Did something built a nest in it? Any possibility something is floating about and wedging, mechanically at odd intervals? Could its position be affected by the strength of the Armature or Field?

Sparking? Damaged brush lead, faulty tamper, hung brush? BENT brush-holder tracking erratically?

Or arcing? And "around" the commutator how?

When last, did you "time" the brushes, and is their mounting plate locked or loose and floating back and forth, in and out of time? Is it cracked?

there was a piece of thin rope that flew off the armature that was causing the sparking. it was the rope or twine that is wrapped around the armature and varnished to hold everything in place. The outer wraps of rope on my spindle motor are coming off.

i removed and inspected all the brushes yesterday. cleaned any debris. all brushes looked good. about an inch long. i didn't time them.
retaining springs where good. everything seemed tight. no more sparking


i just ordered six new capacitors for my RPC

thanks cal, i just ordered six new run caps for the RPC. be here tomorrow

I think I FOUND THE PROBLEM!!!!



Today i followed thermite's advice and operated the lathe in the dark while looking into the headstock cavity
while moving the speed control, i saw a bright continuous light, similar to a tig torch light coming from the rheostat nearest to the front on the machine. The spark or whatever you want to call it, was at the exact spot on the variable speed rotation knob that the machine would go into failure/ bogging mode. i removed the rheostat assembly to find that two of the wraps around the front unit were broken.
is there any way i can repair this?
possibly solder the two adjacent wraps together?
or i will buy one if anyone has one willing to sell

Thanks for all the help
Rich

here is another try at posting the pic