Contactor sound

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etalaat

Member
When i tested a panel contains a contactor, i found that it produce a sound or something like that as a resonance, what is the reasons of this sound?
 

bphgravity

Senior Member
Location
Florida
The contacts are held closed by an electromagnetic coil which likely consists of several layers of laminated steel. The resulting magnetic flux and eddy currents about the coil will cause small vibrations that combine to create sound. This and the sound of the energized contactor within a metal enclosure will be quite noisy but completely normal.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I have disassembled contactors that have cores like I-E transformer cores, with the coil on the stationary E section and the contacts operated by the moving I section.

The moving section usually has a pivot to permit alignment. I have been able to quiet down loud contactor hum by lubricating and excercising the pivot of the armature.

The tighter the moveable part meets the face of the stationary part, the less the hum. If you've ever tried to pry apart an energized contactor or solenoid, you know how loud the buzz can get.
 

mxslick

Senior Member
Location
SE Idaho
Have you guys ever encountered....

Have you guys ever encountered....

...a mercury contactor? :D I use a three-pole one from Grainger's and it makes a peculiar "percolating" sound when energized, regardless of load.

Because of the hazard of the mercury, I don't want to open it up to find out why. :smile:
 
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