ELECTRICALLY HELD VS. MECHANICALLY HELD CONTACTOR

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lizzie14

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could someone please clarify the difference between a mechanically held and an electrically held lighting contactor. also, how to select which one is appropriate for certain applications
 
Re: ELECTRICALLY HELD VS. MECHANICALLY HELD CONTACTOR

electrically held contactors require a constant current and a constant power dissipation to hold the circuit. a common relay or motor starter is a good example of this type of contactor.

a mechanically held contactor is held in place without the need of a constant power drain. the coil on these type of contactors is far less likely to burn up as it is only energized momentarily.
 
Re: ELECTRICALLY HELD VS. MECHANICALLY HELD CONTACTOR

opinion:

mechanically held cost more usually...make no noise except when switched on or off; perhaps less likely to fail over the long haul (again opinion)

electrically held can be a bit noisey;
cost less; use power when on (although not much)
 
Re: ELECTRICALLY HELD VS. MECHANICALLY HELD CONTACTOR

the control sequences are different. the mechanically held contactor requires a voltage to close it and also a voltage to open it. while the electrically held will drop out or open upon a power outage.
 
Re: ELECTRICALLY HELD VS. MECHANICALLY HELD CONTACTOR

Mechanically held usually require additional control relays to operate with photo-eyes. when used with building automation controllers a mechanically held requires both an On and an Off contact

In a super quite area like a broom closet in a library you might hear the coil "hum" from a electrically held device so a mechanical one would be preffered. In a basement boiler room who care about noise.

Life of the coil is not really a concern for most vendors. Magnetic motor starters are all electically held and there are not a large amount of coil failures. But if the device is going to stay on for hours at a time why pay for the coil losses of a 400A contactor, in this case use a mechanically held device.
 
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