Contactor Coil Vibration

Have you checked that you're actually getting 220V at the coils?

Has the vibration started recently? Did it starting coincide with any changes or maintenance work?

i checked that 225 v.

the motor stored for one year then we operated it recently.

no changes or maintenance work occured.

i have cleaned the contacts and i raised the volt from 209 to 225

the vibration still exist

Two possibilities spring to mind :

1) Some dirt or debris has got in between the pole faces and is preventing them from closing. This causes the poles to vibrate heavily.

2) Damage to, or loss of one of the shading rings that are fitted to the pole faces. This also causes the poles to vibrate heavily.

Those also came to my mind, but 1) the contacts have been cleaned, and 2) it seems that all of the contactors are evidencing the vibration - unlikely that they've all been damaged.

I'm at a loss.

Point 1) is more valid as the rusting during idle condions after operation.

point seems not as valid as during storage [that is un-used period after some operatin it is the remotest probability.

As others have said, a broken shading ring or a dirty magnet is most likely to be the cause in most cases. But not here i guess, since you say all contactors are vibrating. Hold on though ... all three? In a wye-delta starter, at any time, only TWO contactors should be on. If all three are ON at any time, there will be a short circuit....?

Dirt or damaged shading rings is correct answer. 1 coil vibrating may fool you into thinking all coils are vibrating. loss of full contact of the coil laminations will cause higher coil currents eventually burning the coil out. Try disconnecting the mains and energising each coil seperatly to find the bad one.

For some time now,u hv nt been using this contactors and no maintenance has been done,so they are likely to vibrate(unusual humming) more than usual.

1) Check and makesure yr A1/A2 coil contact terminals are cleaned for good contact.(2) Check the contactor core surfaces and makesure they are properly cleaned with emery paper and they are well seated,and there is no gap or insulation inbetween upper and lower surfaces.(3) Clean the laminations properly and ensure there is no dirt.(4) Check if the core springs are still active or weak and change spring if possible.(5) Makesure u maintain good 220volts potential at the A1/A2 energising terminals of the coils,even when the motor must have started and running.The coils should not be underfed and not overfed with voltage.(6)Test each contactor seperately and check the vibration(humming) sound,energise and de-energise each several times and vibration would minimise or stop.It may nt be all the contactors that are vibrating,so u can change the one affected.(7) If all is giving u too much vibration,then change their coils and cores or rather change all the contactors,and who knows if the contactors are inferior contactors,u may have to change all,but first,test with a new quality contactor and makesure its okay.Also check if the contactors are appropriately rated to handle the load.

If u dont want to change the contactors despite this unusual vibration,due to cost or any other reason,use them until the noise minimise with time,but ensure that u protect yr motor with good undervoltage and phase failure relay should any line/delta contactor fail.This is not a good option remember.

Patrick Whowha

May not the panel itself that holds the contactors be resonating, because close to the motor?

Pls. make a trial.

Cut off te power line by loosing the motor outputs. This trial will allow you to eliminate the bad contact effects and avoid the confussion.

And now press start to pull the contactors. Two of the three contactors must be pulled at the same time.

Check for any vibration. If yes it may be sourced due dirt on the magnetic surfaces or the shaded pole ring has been broken due the impacts by the time.

You can visually check the (Copper) rings.

Kindest Regards

My experience on situations like this is;

If it WAS working fine before storage, and you have already eliminated a control voltage problem (*or did you? see below), and NOW it is making noise, and it is TRULY making noise on ALL 3 CONTACTORS, then this is going to be rust on the pole faces of the armatures in the contactors. In my entire 30+ year career I have seen exactly 3 broken shading coils, so the likelihood that you have broken shading coils on ALL 3 CONTACTORS is astronomically small. If it was working before being put in storage, that eliminates the possibility of a bad design, incorrect sequence etc.

* But when you checked the coil voltage, did you check it WHEN the contactors were operating? One issue that comes up a lot is that Star-Delta starters are often used on larger motors, which is sometimes the EXACT reason why you get a voltage drop. So if you checked the coil voltage when the motor was Off, the value is essentially meaningless because the very act of energizing that 160kW motor may in fact cause a severe voltage drop that eventually gets to the control circuit.

Apply varnish to the coil and the laminations, it will solve the problem. I had a good experience with the same kind of probem. and I got good results

Spare the mating-faces

I think the problem is caused by a relay used to turn on the contactors, perhaps in the control circuit.

<...how to repair...>

Some possibilities:

• Clean its insides.
• Tighten anything that is loose.
• Replace it.