Old GE Motor Problems

[Cozumel]

Please allow me to re-awaken an old set of posts (https://www.electro-tech-online.com...ld-ge-single-phase-dual-voltage-motor.150379/) and I apologize, in advance, for my lengthy introduction.
I am facing a problem similar to JonesPrecision. I inherited a property in upper New York State that includes a very balky tramway powered by a 1960's vintage single phase 2 hp GE motor. I'm working on replacing the control panel for this system, but to get it right I need to understand the wiring of the motor itself. I've spent hours on the internet and this is the only message board that seems to come close to my problem. The system was designed by a GE engineer at the GE Research Labs in Schenectady, now deceased. The only documentation that I've found are a bunch of tags on the wires leading from the control panel to the motor and a couple of hand scribbled notes inside the cover of the motor junction/capacitor enclosure. None of this is consistent. Some of the wires coming out from the motor have numbers on them, others are clipped and unmarked. The GE wiring diagram on the same panel is identical to the one posted by JP at the beginning of the above thread.

In my Dad's files I found an old GE motor catalog and the model number of the motor appears to be 5KC182JI (maybe JL)240. Nowhere does it tell me if this is a capstart/caprun or just capstart motor. It does use two 340-408 mfd caps rated at 115-125 VAC. Power to the whole system is supplied by two hot leads from a single phase residential supply, implying that the thing is wired for high voltage. The control panel uses four DPST power contactors and two 4PDT power relays for managing the control (pushbutton stop-up-down) inputs and reversing the power to the starting coil(s).

I'm gradually working out how the relay and contactor logic works, but the connections at the motor junction box remain a mystery. There are nine leads coming from the control panel to the motor plus a ground wired to the motor chassis. Two of the leads go to the electric brake and disengage that brake when power is applied to the motor. The remaining six, if I can believe the numbering on the leads coming from the motor are as follows:

1 and 2 connect to the terminals of one of the capacitors
4 connects to one terminal of the other capacitor and the other terminal connects to the control panel relays via a heavy duty yellow lead
5 is connected directly to another heavy duty yellow lead to the control panel
9 and 10 connect to a heavy duty red wire each going to the control panel
Haven't found anything marking 3,6,7, and 8, but at least one of these pairs is wired together

It's hard to tell what's going on with the unmarked leads because they have been clipped short and are hidden behind the rat's nest of other wiring. None of this seems to match with what the formal GE wiring diagram suggests. I believe power to the main windings is supplied via two heavy duty wires coming from the power contactors. Somehow it is also supplied to the two yellow leads that go to the up/down control relays and returned in forward or reverse mode via the two red wires to the start/auxiliary windings and related capacitors.

If someone can help with this, I would be happy to get in direct contact and/or to post photos of various parts of the system. I am reluctant to take apart the motor because it is embedded in a fairly massive arrangement of electric brake, drive shaft, gear box, and cable spool. I'm not an engineer or electrician but am reasonably handy with tools, etc. and have a healthy respect for electric power. My ultimate goal is to replace the current control panel with SSR's and microprocessor logic using an Arduino.

 

[shortbus=]

A schematic of how it is wired or you think it is wired, will help you get more help.

 

[Cozumel]

shortbus=: Don't have a scanner here so here's a photo of a sketch of what I know. As mentioned in my original post, the black leads (which would probably be considered L1 and L2) are connected directly to clipped wires coming out of the motor. There are also two other clipped wires from the motor that are tied together. None of these have numbered markings. The "notes" on my sketch are from the inside of the capacitor/junction box and read:
1,2- Start (Small)
3 4 Run
4- Always 220
5&8 Yellow
9&10 Red
Sorry I can't be more informative at this point.

 

[KeepItSimpleStupid]

Bottom-right hand corner:

Typical symbol for a thermocouple. Red/yel is K (most common). https://www.pyromation.com/Downloads/Data/ColorCodessheet.pdf Possible? If it is a thermocouple, you should get a small voltage (mV) from it. Check for resistance too.
he wires might look different.

 

[shortbus=]

Don't have a scanner here so here's a photo of a sketch of what I know.

If this is a dual voltage motor you need to first figure out how it is wired for voltage, Then the control wiring can be sorted out. There should be a diagram in the lid of the wiring box on the motor, or near the name plate.

There are two members here who are much better at this than me, MaxHeadRoom78 or Les Jones . Maybe they will come and help now that I tagged them.

 

[Cozumel]

KeepItSimpleStupid: I don't think a thermocouple is involved. I believe there is a centrifugal switch on the motor shaft and I need to understand how that connects with the starting capacitor(s).

shortbus=: Part of my problem is that the observed connections don't seem to match the wiring diagram in any way for either voltage. Everything I've learned so far points to the motor running on 230 V. Following is a close-up of the two 4PDT control relays. The thick yellow and red wire pairs coming up from the bottom are the ones wired to the motor in my hand-drawn diagram. Given the cross-over structure seen in the red wires, I believe this is how power to the starting coils is reversed. The top relay activates when the tramway runs up, the bottom one when it goes down. The thinner wires on the two right legs of the relays are the inputs from the various up/down/stop buttons and the limit switches at the top and bottom of the tram rails:

 

[shortbus=]

Well after seeing that rats nest, no disrespect meant, I'd probably pull it all out and start over. Trying to figure out what someone else did and didn't document is a nightmare in my view.

There are quite a few schematics showing what you want to do online and they all follow similar conventions of motor control. But to try and adapt one of them to the wiring that you already have? Not something I would try and tackle, if your time is of any value over the cost of new wiring.

 

[Cozumel]

shortbus=: No disrespect taken and I really appreciate the time you've taken on this. "Rat's nest" was my immediate reaction when I first opened up the control panel AND the junction box on the motor.

Anyone: To "start over," what I'm really hoping for is that someone might be able to draw for me a more complete diagram than the standard GE wiring diagram shown on the motor, showing where the capacitors tie in and how the relay-based phase reversal circuitry should connect to the motor. Below is a hand-drawn copy of the GE wiring diagram which is on a tiny printed label that would be unreadable if I just take a photo of it. Since this is a dual voltage motor, I assume the main and auxiliary windings both consist of two separate coils. Where would they connect? Where might the centrifugal switch tie in to disconnect the start capacitor as the motor approaches full rpm? Given that the two capacitors have the same mfd rating, is this motor designed to run with both capacitors always active? GE must have made a bunch of these motors. This one is vintage 1967. Is anyone out there familiar with the internals of their Tri/Clad KC182T models? Sorry, lots of questions.

 

[shortbus=]

Hi, here is a thread over at AAC that is similar to what you are wanting to do, And he is using motor starters instead of relays. I would use them too if doing this, many relays aren't up to motor control, unless they are chosen for the start up amps of the motor not the running amps.

 

[Cozumel]

Took a look at reversing motor starters. They appear to be overkill for my application (and expensive). A motor starter is nothing more than a contactor plus overload protection. Since we've never had an overload failure on this system, the contactors and relays used are adequate for the application.

Am still hoping there is someone out there familiar with the internals of my motor and able to confirm that this is a cap start, cap run motor with two main windings and two start windings, both operating in series at 230 VAC. How do these hook up inside the motor to the centrifugal switch and outside the motor to the two capacitors? That would certainly reduce the number of variations I need to consider for understanding how the motor has been wired.

 

[Les Jones]

If it is the normal capacitor start capacitor run motor the main winding is straight across the mains. The auxiliary winding has the run capacitor in series with it and the free end of the capacitor and the free end of the run winding connect to the mains. The centrifugal switch is in series with the start capacitor and connects the start capacitor in parallel with the run capacitor until the motor is up to speed. The motor is reveresed by reversing the polarity of either the main winding or the auxiliary winding (But NOT both.) The start capacitor is the one with the largest capacitance value. I can't see any information in your notes to identify the main winding terminals, the auxiliary winding terminals and the centrifugal switch terminals on the motor.

Les

 

[Les Jones]

I have just read back through the thread from the begining. (In post #11 I was just responding to post #10.) I think 1 and 2 are one half of the main winding and 3 and 4 are the other half. I don't think they will connect directly to the incomming mains. I think they will be connected to L1 and L2 when forward and reverse are selected. I think the polarity will be the same for forward and reverse. I susspect that the two red wires that cross over in the picture of the relays are where the polarity reversal is done for forward and reverse. I think these will connect to 9 and 10 on the motor.
Can you measure the resistance between 1 &2 and 3 & 4 on the motor. As I think this is the main winding I expect low readings (Probably less than 10 ohms.) and the reading to be about equal value.
Can you trace out a schematic of all the thick wires from the contacts on the relays ? Can you take a picture of all of the control panel and also the controls used by the driver. (buttons, switches levers foot pedals etc so we get a better idea og tyhe whole thing ?

Les.

 

[Les Jones]

While looking for information on GE dual voltage motors I found this thread that could be a help. (I was involved in this thread but had totaly forgotten about it.) The second schematic in post #7 is not quite right as it shows the centrifugal swtch connected between 9 & 10. This can't be right as swapping over the connections on 9 & 10 would not reverse the motor. I think the schematic is correct but I think the centrifugal switch is not directly connected to both 9 & 10. If you can do some resistance measurments to identify which connection numbers got the the centrifugal switch it would be a great help. It should show a resistance reading of very close to zero ohms. Also if you can check the actual wiring to see how the capacitors are connected that would also help.
I think the motor is only capacitor start. I think the centrifugal switch will be between either 1 or 4 and 9 or 10.

Les.

 

[shortbus=]

Les Jones, hi Les, was hoping you would show up in this. It's a little over my head. Trying to trouble shoot long distance. I have seen no mention of any limit switches yet, which should be in the mix. To keep it from stalling at the end of travel.

 

[Les Jones]

Hi SB,
I just went back to the first post to confirm it was described a a tramway, I remember as a kid we had trams in Liverpool and they had some sort if stepped speed (Or possibly torque.) contol You could feel and hear the step changes. This is why I did not join the thread at first as I assumed it would be some sort of motor that I knew nothing about. (I think the old liverpool trams ran off 500 volts DC) . I also now see that the OP had linked to the link I have just posted. The control panel in the picture looks to in good condition so I do not see why it needs replacing. The relays look rather small for a 1.5 HP motor but they could just be replaced by larger contactors. How's you EDM progressing ?

Les.

 

[shortbus=]

How's you EDM progressing ?

Hi Les. I have the main power board etched and some of the other stuff ready like heat sinks for the power mosfets, but with summer here my electronics projects take a back seat to other stuff. Then I had a series of heart attacks that threw me for a loop.

 

[Les Jones]

hi SB,
Sorry to her about your heart attacks. I hope you are taking it easy and not doing any heavy outside jobs. Like you I tend to do less electronics in the summer. I forgot to mention about limit switches. Witout seeing some pictures of the tramway it would be difficult to suggest a way to implement limit switches.

Les.

 

[Les Jones]

This is how I believe the motor is wired for both voltages.

These numbers are the numbers on the wires in the motor connection box. (A picture of this connection box would be helpful.) I don't know if the motor has the start capacitors fixed to it and not shown in the information on the plate in post #1 of the Jp thread. I don't know if the numbers are terminals in the connection box on the motor or just on wires. The centrifugal switch may be between 1 & 9 rather than 4 & 10

EDIT NOTE I HAVE MADE AN ERROR ON THE 110 VOLT SCHEMATIC. THE LINK FROM 10 TO 7 SHOULD BE FROM 10 TO 8.

Les.

 

[Cozumel]

Les:
Thank you for joining the conversation. My apology for being off line for a couple of days.

Your drawings in#18 look very promising, except there is one of the capacitors sitting on 1 and 2 and suggesting that L1 and L2 are not connected according to the GE wiring diagram (or the wires are mis-marked?). Sadly I have run out of time for working directly on this for this season. The tram is in upper New York State and I need to return home to California tomorrow.

FYI, there are NC limit switches at each end of the tram plus an NO limit switch that closes when the door to the tramway hut is opened. This to prevent someone from trying to run the tram if it is put away in its "garage." The user controls are simple: An industrial looking three button console at the bottom and another at the top. The Up/Down buttons are NO and the Stop button is NC. You only get to stop or start at the very top or the very bottom of the hill. Power management is done by the four high voltage NO-DPST contactors in the left portion of the control panel (see below photo) plus the left two legs of the 4PDT relays on the right. The top relay activates when an Up button is pressed, the bottom one for Down. I have NOT been able to sort out the relay logic -- a project for this winter. I also don't understand why it took four DPST contactors to manage the incoming power. Seems like a single DPST contactor should be able to do this. They are each rated for 30A @ 300 VAC, so maybe it's a way to somehow distribute the inrush current at start-up. The motor draws 12 A at 240 VAC once running at full rpm.

My problem with taking measurements at the motor is that markings on the ten brown leads coming out of the motor are only available for 1.2.4.5.9and 10. The rest are clipped short and without numbers. Two of them are simply tied together and the other two, I believe are connected to L1 and L2 coming from the control panel. Please see my post #3.

Here's the photo of the whole panel. I'll get one of the motor capacitor/junction box before I leave.

 

[Les Jones]

First note in post #18 I have edited it to correct an error I made.
The two wires from the motor that are tied tegether are probably 6 & 7 so the other two should be 3 and 8. Post #3 in the JS thread gives the resistance readings on his 1 HP motor. As your motor is 2 HP I would expect your readings to be about half of his readings.. Measure the resistance between wires 1 & 2 from the motor. This is half of the main winding. I would expect a reading of about 0.5 ohms. The other half of the main winding should be 3 & 4. 4 is marked so measure the resistance from 4 to each of the two unmarked wirers that are NOT joineed together. One of the readings should be about the same as the reading between 1 & 2. The wire that gives this reading will be wire 3. So by a procces of elimination the other one should be wire 8 Measure the resistance between the junction of the two unmarked wires (6 & 7 ??) that are joined together and wire 5. Do the same from the junction of these wires and the unmarked wire that I think is 8. I expect these two readings to be about the same. If there are no capacitors built into the motor I expect these readings to be about 1.5 ohms. If there are built in capacitors then the reading will be low at first but increasing with time as the capacitors charge up due to the test current from the meter. Are you sure that the two relays are 4 pole double throw ? I can only see 8 connections to the contacts. 4 pole double throw would have 12 connections to the contacts. If you look at the way the two poles are linked on the contactors you will see that they are in series so they are behaving as single pole contactors. (I think this is a safety measure.) How do the contactors behave when the up and down buttons are pressed ?

Les.