Sporadic motor trip

[EEENGRX]

I have a three phase Motor that keeps tripping sporadically every time it is turned on. Would not even run for more than 5 mins without tripping.I think this is more of an electrical trip as it is not over amping which has been confirmed
Kindly assist with a troubleshooting plan to use.my thoughts are
Electrical wiring
Bad coil
Aux relay
Start/stop
Skinned wire

 

[LittleInch]

If it runs for a while then it could be overheating?

Very vague description which doesn't tell us much, if anything.

E.g. is this a 5kW machine or a 5 MW machine?
220V or 6.6.kV ?

Tripping sporadically and every time it is turned on are not the same thing. Sporadically means only sometimes, not every time.

You've started 11 threads and only bothered replying to 6. Why?


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EEENGRX]

Thanks for your response.it’s a 230/460 V
4.4/2.2 Amp with S.F of 1.15 motor. It runs for like 5-6 mins and then shuts down.it’s not over amping as that’s already confirmed .What do you think?

 

[LittleInch]

How does it "shut down"? if the breakers are not being tripped?

Somewhere the power is being tripped due to something being out of range. We can't see what you can see so impossible to say.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EEENGRX]

Now I have new new info. It ran for a day and a half and then tripped on overload, next time it ran for half a day and tripped on overload and third time it ran for like six hours and tripped and now it runs for about six minutes and then trips. For each time it runs , the amp draw is checked and it’s usually at 2.1/2.2 eroding the possibility that it’s over amping

 

[Compositepro]

Perhaps a loose electrical connection near a heater in the starter.

 

[EEENGRX]

Aiite.. thanks for your input

 

[LittleInch]

Check the breaker.

What is is powering as it is running at 100% load.

But it's a 1kW motor. Just replace it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[edison123]

Faulty breaker. Change it.

Muthu

http://www.edison.co.in

 

[RRaghunath]

I guess the overload setting is lower than it should be considering the actual loading and SF of 1.15. Did you check that possibility?

 

[EEENGRX]

Yes I did and it’s set correctly. I suspect bad coil, aux relay bad wiring or skinned wire

 

[RedSnake]

You haven't told us what your set motor breaker value is?
Or what kind of breaker it is?

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[jraef]

If the Overload Relay is tripping, it’s not a bad coil, aux relay, etc., an OL trips because the current is too high. Plain and simple.

Did you check the current in all 3 legs to make sure they are balanced? IEC and Solid State OL relays will skew the trip point to be lower than the setting if there is a phase loss. So even if the current in one or two of the phases is “normal”, it can still trip if there is no or low current in the 3rd phase.

Another possibility is that your control signal that engages the starter is chattering, making the motor starter bounce on-off-on-off-on-off really fast. That causes the current heating effect in the IL relay to trip it off line even though when you read it at steady state, it appears normal.

Another possibility is that vibration has worn away the insulation in the motor connection box and occasionally the mechanical movement in the motor causes it to short to ground, but in a high resistance manner that is not causing the breaker to trip first.

Bottom line, this needs sone expert troubleshooting based on starting with what you KNOW moving toward what you don’t know.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[EEENGRX]

It is not tripping on overload. It just runs for a few minutes and shuts down. Trip settings is correct and Amp draw is also good. Do you now understand my point?

 

[RedSnake]

Do you run it on a converter or on a old fashion motor breaker?
Is motor connected Y or D ?
I think the start current can be much higher the 1,15 Amps for a short while.
1,15 is what the motor can take in short periods with enough cooling in between.
Have the motor got a fan or a break?

Sorry if I have a many of questions..


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[RRaghunath]

If Overload relay is causing trip in spite of setting being correct and the motor current at below the set point all the time, we need to suspect the relay itself. Questions to be addressed are:
* Is the relay Bimetal type?
* Is the relay tested and its performance confirmed?
Bimetal relays are known to lose calibration over a period of time.
In case of Single phasing also, the bimetal relay is supposed to operate at currents below the setting, hence, checkout - Is there a possibility of single phasing (loss of one of phases from supply side, for whatsoever reason) just before the trip is happening.

 

[LittleInch]

One of your posts said it trips on overload, then you keep saying it's not tripping on overload??

It appears to be set very close to the max current.

What is this motor driving? Can you get occasional overload?

What type of breaker do you have?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EEENGRX]

O thanks for the solid info. I’ll look at the breaker and troubleshoot the breaker down to the motor itself

 

[RedSnake]

For a none American and someone who don't have English as my first language, I need to ask, are you being sarcastic now?

It would be much easier to help, if you answered our questions.

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[jraef]

“Shutting down” is not something a motor that size does on its own, SOMETHING is either tripping or dropping out. If as you seem to believe, nothing is tripping, then it’s a control circuit problem somewhere. A bouncing contact, an interlock you were unaware of, a broken control wire, something like that.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden