Lathe motor starter help

[Thumper68]

My Sheldon lathe was working just fine, I shut it off and came back not even 30 minutes later and it wouldn't start, when I push the start/on button it makes a buzzing sound but no click like it used to, I'm guessing that there is something wrong with the motor starter or the switch, I tested the momentary switch and it works.

Square D
Nema size 00
Class 8536
Type A

M0330-F

Looks very much like this one, sorry I am having issues uploading pics so a image from the web will have to do.

http://bullseyeindustrialsales.com/square-d-class-8536-nema-0-motor-starter-type-sbg2-240v-coil-3ph-enclosure-111341

I have a few questions
1) is there a way to bypass the unit? I have a job that needs doing and since it is Friday I doubt I can get one before next week.

2) can anyone point me to a suitable replacement? Motor is a 1hp 240v 3ph

Any and all help is appreciated!!

 

[Thumper68]

Bump

 

[sdwalter]

Here is a suitable replacement starter for what you described. In terms of trouble shooting, i would start with the over current protection. Make sure the fuses are not blown or the circuit breakers tripped (in the starter, not the panel)
https://smile.amazon.com/gp/aw/d/B0...r+3ph+240v&dpPl=1&dpID=31kklo4LSeL&ref=plSrch


Sent from my SM-G920V using Tapatalk

 

[bri_man57]

Does it start if you spin the chuck by hand while it's buzzing?

Sent from my SM-G900T3 using Tapatalk

 

[metlmunchr]

Have you verified that the overloads aren't tripped? Doubt you'll find anything over the weekend as the home center type places don't typically keep anything in 3 phase equipment.

Another thought.... does the starter have a line voltage coil or is it reduced voltage like either 120V or 24V? If it has a control transformer to provide a reduced voltage control circuit then you might check for proper voltage at the leaving side of the transformer. If you found a dead 120V control transformer then you could temporarily supply the 120V control power via disconnecting the wires from the leaving side of the txfmr and tying them to another source of 120V power, such as a piece of cord plugged into an outlet and wire nutted to the control circuit.

Assuming your lathe has a clutch lever on or near the apron for engaging the spindle drive, you could bypass the starter on a temporary basis to get your job done as the starter in that setup does nothing but start the motor and provide overload protection. OTOH, if pushing the start button normally starts the spindle then I'd say it would be way too unsafe to bypass the starter even temporarily.

In reality, you could bypass the contactor section of the starter and still keep the overload relay section in the circuit by adding jumpers across each leg of the contactor. But, to do this you'd need to be familiar with how the starter is wired, particularly relating to any NO or NC auxiliaries and whether any of them might need to be disconnected to prevent backfeeding.

I'm relatively sure some of the more code-obsessed members will let us know you'll likely die if you bypass anything, but sometimes you just gotta do what you gotta do to get the job done. I had a 100 amp 3 pole breaker feeding one of my cnc turning centers that decided to puke on a Sunday afternoon when I was about 3 hours away from finishing a job I'd promised for first thing Monday. Took me about 10 seconds to decide whether I'd worry about codes or grab a piece of 10/4 SO cord, wire it into the main disconnect on the lathe, and plug it into a nearby 50 amp 3 phase outlet. The thought of making an excuse to the customer, or delivering the work and pocketing a $4500 check by 9am the next morning made that decision real easy

 

[Thumper68]

Here is a suitable replacement starter for what you described. In terms of trouble shooting, i would start with the over current protection. Make sure the fuses are not blown or the circuit breakers tripped (in the starter, not the panel)
https://smile.amazon.com/gp/aw/d/B0...r+3ph+240v&dpPl=1&dpID=31kklo4LSeL&ref=plSrch


Sent from my SM-G920V using Tapatalk

Thanks for the link.
The over load seems fine.

Does it start if you spin the chuck by hand while it's buzzing?

No it does not, from my rudimentary knowledge the momentary switch just closes the contacts and that is what is not working.


Sent from my SM-G900T3 using Tapatalk

Have you verified that the overloads aren't tripped? Doubt you'll find anything over the weekend as the home center type places don't typically keep anything in 3 phase equipment.

Another thought.... does the starter have a line voltage coil or is it reduced voltage like either 120V or 24V? If it has a control transformer to provide a reduced voltage control circuit then you might check for proper voltage at the leaving side of the transformer. If you found a dead 120V control transformer then you could temporarily supply the 120V control power via disconnecting the wires from the leaving side of the txfmr and tying them to another source of 120V power, such as a piece of cord plugged into an outlet and wire nutted to the control circuit.

Assuming your lathe has a clutch lever on or near the apron for engaging the spindle drive, you could bypass the starter on a temporary basis to get your job done as the starter in that setup does nothing but start the motor and provide overload protection. OTOH, if pushing the start button normally starts the spindle then I'd say it would be way too unsafe to bypass the starter even temporarily.

In reality, you could bypass the contactor section of the starter and still keep the overload relay section in the circuit by adding jumpers across each leg of the contactor. But, to do this you'd need to be familiar with how the starter is wired, particularly relating to any NO or NC auxiliaries and whether any of them might need to be disconnected to prevent backfeeding.

I'm relatively sure some of the more code-obsessed members will let us know you'll likely die if you bypass anything, but sometimes you just gotta do what you gotta do to get the job done. I had a 100 amp 3 pole breaker feeding one of my cnc turning centers that decided to puke on a Sunday afternoon when I was about 3 hours away from finishing a job I'd promised for first thing Monday. Took me about 10 seconds to decide whether I'd worry about codes or grab a piece of 10/4 SO cord, wire it into the main disconnect on the lathe, and plug it into a nearby 50 amp 3 phase outlet. The thought of making an excuse to the customer, or delivering the work and pocketing a $4500 check by 9am the next morning made that decision real easy

Thanks for all the direction, but since I am not really well versed in how exactly this stuff works I will just order a new starter.

BTW I realized as I was getting ready for bed that I am a idiot, until a few weeks ago I was running the lathe on a VFD, I switched it back to the motor starter and drum switch when I got the phase converter set up to run that and the mill, I will just set the VFD back up until I can get the new starter.

 

[larry_g]

Can you confirm the RPC by running the mill? That should eliminate it as a problem. I also said something about making sure the controls coils are not on the generated leg, this is one of the problems you can have. Not saying it is but could be.

lg
no neat sig line

 

[Thumper68]

Can you confirm the RPC by running the mill? That should eliminate it as a problem. I also said something about making sure the controls coils are not on the generated leg, this is one of the problems you can have. Not saying it is but could be.

lg
no neat sig line

Yup I made sure the mill still functioned and since I used plugs I switched outlets to make sure that it wasn't a bad connection and the mill runs fine.

I also made sure that the control power was not on the generated leg, I remembered that from the other thread and checked it, twice when I was wiring it and again today to make sure.

This is a old unit, from a school so I'm sure it was cycled 1000's of times and it just picked now to give up the ghost.

On Monday or Tuesday I will swing by Graybar and see if they have anything in stock, if not I will order one. The one in the link provided above looks like it will work.

 

[matt_i]

There is always the method of manually depressing the contact in the "relay" as a form of troubleshooting. A 1000vac insulated screwdriver is the best tool for the job but others have used pencils and plastic sticks and lived to tell about it. The actual parts making contact are usually well-insulated.

This gives you a very fast indication of whether the problem lies on the "power side" or the "control side" of the relay and also eliminates a hybrid issue like the coil voltage is too weak via high resistance connection or a "leak" to ground to fully snap the contact closed.

If its a true NEMA-rated contactor then I like to buy them used. New prices will not make you happy. If new is required then an IEC-rated contactor will be less money and do the same job. Your best bet might be at Automation Direct. The NEMA-duty starters are built for many years of heavy industrial switching, and the IEC versions, while adequate are not that heavy. Rough analogy: NEMA = 3500/F350/1ton, IEC = 1500/F150/0.5ton

 

[Thumper68]

Yesterday I switched the lathe back over to the VFD and it is running just fine now, I will be picking up a new Starter later this week if I have time.