lighting relay

[normbac]

I have 25 2x4 trough lights 277v when I connect them to a relay which has a 120 coil, 600v max rated 30a it got so loud I immediately shut it down, works fine with no load. it says when using above 240v to break all lines? Not sure what that means though. Any thoughts TIA :? Square D 8910DPA34V02

 

[jcbabb]

How much load?

How much load?

What type of lamps and ballasts do you have in each troffer? Do you know what your total load is?

 

[normbac]

not sure on ballast they were existing fixtures 3 lamp @ 277 approx 10a load

 

[Smart $]

Loud in what way? That is, describe the sound.

To "break all lines" means to switch all circuit conductors with the relay. If circuit(s) are MWBC, you can typically switch all the ungrounded conductors and not switch the neutral.

 

[normbac]

Same sound as when a contactor goes bad and humms so loud you a service call to come out and replace it

 

[Smart $]

Same sound as when a contactor goes bad and humms so loud you a service call to come out and replace it

Were you breaking all lines?

 

[normbac]

Not sure if I know what break lines means it is a four pole contactor and i put 277 leg to L1 and load on T1. I did not use L 2 3. Or 4. Or. T 2 3 or 4

 

[Smart $]

Not sure if I know what break lines means it is a four pole contactor and i put 277 leg to L1 and load on T1. I did not use L 2 3. Or 4. Or. T 2 3 or 4

Break all lines over 240V would mean for a 277V two-wire circuit you'd have to swich both the line and neutral conductors.

 

[normbac]

Oh ok let me try that. Thanks for the explanation

 

[capybara]

we assume there are 25 - 2 tube fixtures. each fixture approx 100w including its ballasts. 2500w/277v = about 10 amps like you said. should be no problem for a 30Amp contactor. and yes, I would use the contractor to open the neutral. if that doesnt work, that contactor maybe bad.

 

[Flux]

Sounds like a problem with the coil not the contacts you might want to look into a latching contactor with a momentary contact switches.
You could always open it up and take a look inside at the contacts deenergized and on the ground of course:thumbsup:.

 

[Smart $]

Sounds like a problem with the coil not the contacts...

He said "works fine with no load" in the OP... with load "it got so loud I immediately shut it down"... then later said "Same sound as when a contactor goes bad and humms so loud you a service call to come out and replace it."

If the instructions say break all lines for over 240V, it is likely because at the higher voltages the magnetic field produced by the make-contact arc (especially on reactive circuits) is enough to interact with the magnetic field of the coil, causing the contacts to "chatter".

 

[Flux]

Smart $ Uh yeah that was my other guess. I will have to hit the books on that one.