Noisy Contactor

It's probably some crud between two parts that are brought together when the contactor is energised.

Either strip and clean, or component-exchange maintenance.

Noise in the contactor could be due to Chattering (improper coil voltage, no shading rings, improper mounting of shading rings, loose core laminations, dust on core surface, etc.), Humming (dust on magnetic surface, inter-turn short in coil, improper coil voltage, etc.). Please check for the above.

But, your case could be more serious as you have said that the cores are touching. This clearly indicates that the contactors effective mechanical life is over and you need to change the contactor immediately.

The failure possibilities are that the contactor may fail to drop off even when the coil supply is removed, if your cores are touching. This could be serious.

core is not touching

coil voltage rating is 440-480VAC,measured voltage on coil terminal 474V

no loose core lamination

core surface is clean

shading rings mounted near surface of core

17 contactors is having same problem

revised question:

we are having these noisy contactor for our 110KW,480V.A.C.,60HZ motors,we observed that there is no gap on the contactor contacts and the magnetic core is clean of any dirt but when the contactor is closed a loud humming sound can be heard.the power supply of the magnetic coil is 480vac/60hz...what could be the cause and possibilities that this will fail???

The causes for a contactor to hum or chatter have all been given.

However..... Do the contactors (17 of them as you say) switch on simultaneously? If so, the coil inrush of so many may cause a voltage dip which would result in that noise. This assumes that the noise happens only at switch-on point, not when they are fully On.

A hum of about 40dB is normal and ok. Anything more is indicative of incipient malfunction.

the contactors are not switch on simultaneously,some is in off condition but whenever any of these contactor is switch on this loud noise will take place

the loud noise will stay for a couple of days after contactor is closed then gradually reduced but still humming

A couple of days, that is strange. In my experience, hum is due to imperfect seating of magnet surfaces, mainly due to dust (even a few microns is enough), also due to poor manufacturing, which may cause friction on the moving system. Who is the manufacturer ?

A broken shading ring causes such a violent noise that it is unmistakable. It will also cause rapid destruction of the contactor. Not likely in your case.

Magnetostriction causes a mild hum and is almost undetectable. Well below 30dB. Not to worry.

Eddy current, hysteresis etc are part of ferromagnetism, and any designer worth his salt takes care of these in design. Use of a good grade of CRNGO laminations with a good organic insulation on them will take care of these. Almost universally used.

Check whether a 50Hz coil is being given by the manufacturer. Check whether the supply is strong enough not to dip due to the coil inrush current, which can be 10X of the sealed (steady state) current.

If nothing comes to light, think of using one of the new contactors which have microprocessor-driven coils like ABB's AF contactors. Worth the price.

http://www.abb.com/product/ap/seitp329/286bf18a1f08aa2ac12577c100484835.aspx

the contactor manfacturer is Furnas(size 5)

Wow. Siemens and Furnas are two of the most respected names in the contactor business. They invented many danged things in that line

i am curious as to what they will have to say about your problem. If you are in USA, a call will bring them swarning to study and solve your problem i am sure. They will take pride in their products. At least they should

This is a small cameo in their Innovaplus contactor range....look at the simple, brilliant idea....

A question within a question... Would running 60Hz equipment in a 50Hz world cause a problem, or is a coil a coil and it doesn't care ??

In most cases, there is a difference, due to change in inductive reactance when the contactor is open and again when it is closed. So the 60Hz coil needs to be different from the 50Hz one. Since Furnas is American, the default design is 60Hz. In some smaller contactors, a 50Hz coil can be re-rated for a higher voltage at 60Hz.

Nowadays, since the trend is towards electronically controlled coils wherein the coil is inherently a DC one, it does not matter, the same coil is offered for DC, 50 and 60Hz control supply.

So.... If a 60Hz coil was being energized by a 50Hz source would it pull in " harder " or make and break at a lower rate causing some hum or vibration ? ( I ask these questions as I have never been around a 50Hz source ).

In general ... Yes.

A normal 60Hz coil, if energised on a 50Hz supply, will draw more current, and in due course, may burn out. It will also close with more impact, perhaps with more contact bounce, so some small detrimental effects. Sometimes, it will be possible to dual-rate the coil, like here....(please note the highlighted ones)

i am, however, impressed by the new microprocessor-driven coils. Here is an example from ABB....note that the same coil is used from 48V to 250V ! And for DC, 50 and 60Hz. Since the coil is inherently fed by pulsed DC...

Thank you..... I now have my mind wrapped around that information... It doesn't serve me now, but it will in the future......or maybe not..... but it will be there if I need it... Thanks again....

You are most welcome. The images are not that readable, since CR4 necessarily have to keep them small, so if you need the actual catalogs, please ask, i can give links. Or the actual documents if you give me your mail id.

Good luck.

Sir it would be great if you can share the link of the microprocessor based coils for contactors...

The best is this ABB patent... http://www.google.es/patents/US20090219119

You can also search for ABB AF contactor catalogues which are quite comprehensive. Nevertheless, there is no better way than to buy a few contactors and study them.

All contactor manufacturers have these electronic coils nowadays. You need to study different ones to see how they do their designs if you want to become knowledgeable. Good luck.

Thank you Sir!

Sir my contactor has coil of range 140- 270 v. It is silent at around 170 volts, as soon as I increase the voltage aroun 200V it starts humming...what can be the reasons for that...

There is no gap in the core segments when the relay is closed ? May be it may not be visible but there can be rust on core, or it may not be properly aligned. These are the two main causes of core humming. If the relay is very old and if still it continues to hum due to chattering after cleaning and properly aliening we had a method of putting a copper ring inserted the core close to the face , which reduces the core humming. The core humming will cause heating of the coil and can cause failure of the coil. The important preventive check to be done is cleaning and realigning of the core and contacts to avoid failure.

magnetostriction

the noise maybe generating by eddy current lossess.....cheak the coil its becomming week so that the magenetic attaraction is poor thats why your core is not complety touching the coil core....

Sounds to me like you got a batch of bad contactors....It happens...Try a different brand in one and see...

If they're a few years old, and depending on their usage, I'd bet they're worn out, replace them all; believe me, down time and your time cost much more to the company.

Regards

Some brands of contactors are just built very cheaply and they make a lot of noise. There is also a serious problem now of Chinese counterfeits making it into the market, and they have no reason to make a quality product if the buyer is assuming they are buying a name brand product. If you purchased these at a price that seemed too good to be true, it was.

I have observed this with several different makes of contactors.

Sometimes it is just a little rust on the pole faces, a little dirt, the pole faces not coming together quite square.

Solution has been cleaning. If that doesn't work then replace.

It is also quite common the next time you open and close the contactor it will be quiet.

C21236, Dismantle the contactor and clean it, there is some foreign material between the armature and its base.

Best Regards

Joe

it has been dismantled and cleaned with same result...we are trying to replace this coil with a new one but we could not find same in the market, could be this type of coil has been phase out due to this problem,

If these are old contactors there is a high probability the guides for the armature are worn, especially if they have gone through numerous cycles. If the pole pieces don't line up square with each other they can make a racket. These are somewhat generic contactors. Don't look for pieces, replace the whole assembly.

No Mate, it probably has just sh*t itself, it happens mate. Things don't last forever.

Best Regards

Joe

Magnetic permeability maybe. We have a lot of older 250~400 HP. Starters, some are noisy some are not. We don't pay any attention to it unless an IR anomaly shows up on the camera on inspection. The "hummers" do make you think more about safety.

Please give details of contactor,data plate info, etc., and photo if possible, and perhaps we can find a suitable replacement.

Need motor data also,Voltage, FLA, Service Factor, in order to specify proper heater sizes.

Is it due to Power Quality ( specially presence of Harmonics) problem ? Just a guess, since all probable causes are explored and checked and found O.K.

Manindra.

I agree. Perhaps. Fluke 1735 could help you check power/load quality. If problem did exist, may be its time to replace a higher coil force to contact rating than existing ones.

Could be poor contact pressure because of failing coil

Check line current and compare with the other contactors

Check volt drop on this particular contactor when in and compare with others

Check for loose wire terminations

JS

Sounds like worn components inside(Guides,shading coils with hairline crack,or damaged armature). Replace the contactor.

The absolute toughest contactor I have ever encountered is a General Electric.It was in a reversing starter that ran clip controls for a textile oven.It cycled about once a second for 24/7 for 365 days a year, and was replaced annually as a matter of routine.It was still working fine, with no humming, although the armature was severely peened from over 3 million operations, and the shading coil was exposed and making contact on the stator when closed.Still worked flawlessly.

Unless your mounting space makes it impossible, replacing the contactor with any brand size 5 should be possible.I recommend making a backing plate adapter using the existing contactor as a template, and mounting your new contactor to it, then it will be simple to replace all of them quickly by prefabricating the adapter plate and pre mounting the new contactors.

hello disconnect the contactor disassemble the contact point then grad a sand paper clean it thougthly then assemble again then try to connect see what will happen, if the sound is still there i suggest you to replace a new one

Furnas stopped production of the NEMA Size 5 contactors even before Siemens bought them in 1995, partly because they had problems with the design. They (Siemens) quit supporting it with spare parts production in around 2004 I think. So 8 years after the final production of spare parts is a little long to be expecting to repair this thing. It's time to retire it.

This was a VLGD design contactor, Vertical Lift Gravity Dropout. The contacts were self-aligning and self wiping, a very good design as far as that goes, so the suggestions of sanding the contacts etc. are not only pointless with regards to fixing this issue, but will actually SHORTEN any remaining life in them. Most likely the problem is that the magnet wire in your coil is now old and suffering from insulation breakdown so it is "leaking" turn-to-turn, which means it is not providing adequate magnetic field strength. Your choices are as follows:

1) Buy a "NIB" (New In Box) replacement coil if you can find one somewhere, like FleaBay, or surplus components dealers such as PLC Center etc. Do not waste time buying a used coil, it will be as old or older than the one you already have. The NIB versions will be as well, but having not been used, they have not been subject to heat and corrosive environments like a used one will have.

2) Find someone who will rewind that coil for you. Good luck with that.

3) Throw in the towel on that old dinosaur and buy a new one. The only one like it on the market any more is the Allen Bradley Bulletin 509, specifically a 509-FOU (480V coil) and I personally would use the E1 Solid State overload relay, so option -A2N because it is adjustable from 60-300A, no more heater elements. You can get other IEC style horizontal action contactors, but often times people chose the Furnas or A-B VLGD contactors because they stand up to high vibration much better than horizontal or "bell crank" style contactors. If your starter is mounted to the machine directly, I would stick with what you already know lasted 20+ years. If it's in an old Furnas MCC, I know you can now replace it with a Siemens NEMA rated IEC style contactor (3RT12 I think) because Siemens UL listed them that way, but you will have to put in the ESP200 overload relays as well. If it's off somewhere else hanging on a wall, any contactor that will fit the space would do.