Big contactor

[Eire79]

Well guys ,
I have been looking at a big contactor for a power factor unit which is buzzing mad and causing a lot of vibration/noise to adjacent containment
So I opened up the front end and to me the contacts have a lot of wear from loading as you will see on attached images .
Would you agree that it's a cause or making problem worse as I know the inductor is below it and that humms also.

 

[James]

if the contactor is buzzing, change it for a new one. it will help.
however that looks like an old contactor from pre 1980, has the PFC equipment been serviced recently? because there can be problems with capacitors of that kind of age.
partley due to the way they were made and the possibility of them containing pcp's
also, due to the age they can be worn out and ready to fail.

You really need to know what you are doing to be working on equipment like that, be careful.

 

[R-fur]

I agree with everything James said.
Rather than changing to a new contactor it may be worth considering an air circuit breaker with electrically charged springs, that way you can combine the protection and control elements.

 

[Eire79]

It's 1991 on the wiring diagram, so it's old and possibly due an upgrade . Built by Nokian capacitors.

 

[Lucien Nunes]

Those contacts aren't too bad overall. They've seen a fair amount of use which is why there are deposits on the arc chutes etc, but they are not deeply cratered and have not lost that much metal. Unless there is some other reason for them to be arcing, they are not the source of your buzz. That's most likely mechanical, a quick clean of the armature and pivots and a check for any loose fasteners might cure it.

 

[Pete999]

It doesn't look as if this contactor is subject to any form of maintenance regime, those contact need dressing, cleaning to ensure correct seating when engaged, yes that could be the root of your problem, certainly some chattering will ensue if the problem is not addressed on a regular planned maintenance schedule.

 

[Eire79]

Contactor hasn't been opened since install 19 yrs ago id say and it's usually always in circuit to 400 kvar caps. Does the armature come out from the front end also

 

[Andy-1960]

As Lucian says, those contacts are not too bad at all, however I can see surface rust on the contact springs, if there is rust on the armature facings it will buzz like mad. What make is the contactor?

 

[Pete999]

As Lucian says, those contacts are not too bad at all, however I can see surface rust on the contact springs, if there is rust on the armature facings it will buzz like mad. What make is the contactor?

Sorry LUCIEN "Not to bad" they are far to pitted and need dressing and adjusting to perform at 100% efficiency or as near as possible to 100% sadly lacking in maintenance.

 

[David Prosser]

Contactor hasn't been opened since install 19 yrs ago id say and it's usually always in circuit to 400 kvar caps. Does the armature come out from the front end also

29 years ago ??

 

[Eire79]

i forget the make at this stage but yes the rust is pretty bad and i will remove the armature and give it a clean down, and yes 29 yrs my mistake its a fair long time in service at this stage so maybe a whole new system should be on the cards.
also today while looking at it the inductor is also contributing a fair amount of humming to the overall noise and even the fan on the door when operating causes a fair bit of rattle to the door.

 

[Megawatt]

Well guys ,
I have been looking at a big contactor for a power factor unit which is buzzing mad and causing a lot of vibration/noise to adjacent containment
So I opened up the front end and to me the contacts have a lot of wear from loading as you will see on attached images .
Would you agree that it's a cause or making problem worse as I know the inductor is below it and that humms also.

The buss and contacts have changed colors and that tells me it’s lost it’s ability to conduct electricity and I’m sure it hums

 

[marconi]

It's 1991 on the wiring diagram, so it's old and possibly due an upgrade . Built by Nokian capacitors.

Out of idle curiosity would you be kind enough to send me the wiring diagram - perhaps take a photo.

My tuppence worth of advice is:

1. Check the voltage across A1 A2 is still in spec.
2. Check the sealing current is in spec.
3. To extract dust suck with a vacuum cleaner instead of blow with an air line.
4. Think about whether the coil has overheated and caused some obstruction/resistance which now prevents the magnetic circuit limbs closing properly to minimise the air gap.
5. What new loads have been installed over time which in amalgam may now be distorting the mains voltage waveform and thence the current through the contactor coil and extra harmonics for the PF circuitry to handle. eg: LED lighting in lieu of flurry? Switched Mode PSUs....
6. Find out if the site is charged £sfor reactive power; a dumb blunt PFC system may no longer suit and a smart PFC system may become cost-effective.

This is an interesting and rather unusual topic for the EF so would you please provide some updates?

 

[Eire79]

Out of idle curiosity would you be kind enough to send me the wiring diagram - perhaps take a photo.

My tuppence worth of advice is:

1. Check the voltage across A1 A2 is still in spec.
2. Check the sealing current is in spec.
3. To extract dust suck with a vacuum cleaner instead of blow with an air line.
4. Think about whether the coil has overheated and caused some obstruction/resistance which now prevents the magnetic circuit limbs closing properly to minimise the air gap.
5. What new loads have been installed over time which in amalgam may now be distorting the mains voltage waveform and thence the current through the contactor coil and extra harmonics for the PF circuitry to handle. eg: LED lighting in lieu of flurry? Switched Mode PSUs....
6. Find out if the site is charged £sfor reactive power; a dumb blunt PFC system may no longer suit and a smart PFC system may become cost-effective.

This is an interesting and rather unusual topic for the EF so would you please provide some updates?

I will indeed send on a photo, I have also since stripped down the contactor to clean the internals with a hoover of course but the buzzing remains and I know at this stage the inductor is causing a lot of it properly due to loosening of the varnish sealing around it , age etc.
Then a few days later the coil went in the contactor so they have no pf in that part of factory now and iv noticed that the screen is reading .96/.97 which is due to no load on in that bay due to downturn in production.
I also maintain that it must have been over compensating because if the unit was now in operation the bank would be pulled in as it never seams to be off.
I have also contacted ABB about replacement contacts and coil but the model is no longer available so they have specified a replacement type.
Going forward i am pushing for a new system plus i guess a power quality analisis to see true load and spec new cap bank for same, also as you suggest the load has changed since original installation due to completely new machinery and the latest upgrade of led lighting approx. 500/600 fittings in that bay alone.
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And even now as I think about it the production maintenance lads had a lot of expensive power supplies blowing on drives in grinders which could be as a result of over compensation harmonics etc.