Contactor not pulling in

[VAsteamfitter]

Was scratching my head this afternoon. Replaced a PE switch for an Indeeco Duct heater. Calibrated thermostat, calibrated switch for when it sees 13psi of air the NO switch will close and send a 277 signal to my stage one contactor coil. Checked for continuity when the switch closed (13psi) before I applied power; good. Applied power, increased thermostat for full heat, stage 2 and 3 pull in but 1 doesn't. Manually pushed in stage 1 contactor , felt a slight bit of resistance but then it pulled in magnetically, stayed closed for a bit, had amp clamp on line side to heater and amps were within reason, then it opened. Cycled power, contactor made, then it broke. Decided to replace contactor. 2 pole, 30 amp, 277V coil. Wired it up exactly how it was and confirmed via schematic. Applied power with full heat call and nothing. Stage 2 and 3 close but 1 doesn't. Checked for potential across my PE switch 0. Check for voltage at coil ( coil terminal 1 and terminal 2 ) 0. Coil terminal 1 to ground 277, Coil terminal 2 to ground 277. Check the continuity of the wires all good. Any help would be great

[IRBH]

What's measured voltage ACROSS coil?

Stop measuring to grnd, measure v across switches etc to find the under-load poor connection.

[pecmsg]

277 to ground?

What PPE did you have at the time?

[IRBH]

277 to ground?

What PPE did you have at the time?

PPE?

Post Partum Elation?

[VAsteamfitter]

voltage across the coil was zero as I had stated but didn't describe it well enough. This is a duct heater from 1989. all circuits are 277. line side and coil side.

[IRBH]

Is your coil #2 out returning to the wrong leg of 277v ?

And you're sure there's NO v drop across actuation switch?

[timebuilder]

I think it's right in front of you.

You have zero across the coil, BUT you have 277 to "ground" on both sides. What does that tell you? It tells me that the common side of your coil is nearly open, has high resistance due to a bad connection, or there is a control in the common side that has high resistance.

Your problem, either way, is in the circuit on the side of the coil that does not have the PE switch.

[Deltashmelta]

Dumb question but is this three phase? I recently went round and round with a 220v pond pump and found out the voltage on the contactor coil, I was reading each side both from L1 and thought the contactor had voltage only to find that I had to have a jumper to the other L2 leg to make the 220v contactor work.

[VTP99]

Dumb question but is this three phase?

You get 277 volts from a 480 volt 4 wire Delta Y service. Any phase with the neutral will yield 277 volts.

[timjimbob]

Even though voltage is high, it is exactly like how 120 volts' neutral is derived on a 208 volt three phase service. Except the service is derived from 460 volt, three phase. 277 volt is never three phase, one side is at zero potential.

[Hrdworkingacguy]

There is a break somewhere between the coil and neutral...did they break neutral with a contact somewhere that is open?

[VAsteamfitter]

There is a break somewhere between the coil and neutral...did they break neutral with a contact somewhere that is open?

Every other switch within the circuits are closed , APS, manual and auto thermal cutout, and stage 2 and 3 heater contactors are closed and heating. those are all that is there.

[Hrdworkingacguy]

277v coil is a 277v line on one side and neutral on the other. If you have 277 on one side, and no 277 when you go across the coil, and it doesn't pull in, then you don't have a path to neutral, period...

Put one meter lead on neutral and work back to the coil, somewhere you will get 277v and that's your break.

[timebuilder]

I think someone else said that.

Wait a minute, that was me.

[primmers]

i love this site..

[Hrdworkingacguy]

I just said it in a different way after the op challenged our diagnosis.

In all honesty I skimmed after the first couple posts..

[BBeerme]

Pretty hard for a contactor to pull in with no potential on the coil.

Was scratching my head this afternoon. Replaced a PE switch for an Indeeco Duct heater. Calibrated thermostat, calibrated switch for when it sees 13psi of air the NO switch will close and send a 277 signal to my stage one contactor coil. Checked for continuity when the switch closed (13psi) before I applied power; good. Applied power, increased thermostat for full heat, stage 2 and 3 pull in but 1 doesn't. Manually pushed in stage 1 contactor , felt a slight bit of resistance but then it pulled in magnetically, stayed closed for a bit, had amp clamp on line side to heater and amps were within reason, then it opened. Cycled power, contactor made, then it broke. Decided to replace contactor. 2 pole, 30 amp, 277V coil. Wired it up exactly how it was and confirmed via schematic. Applied power with full heat call and nothing. Stage 2 and 3 close but 1 doesn't. Checked for potential across my PE switch 0. Check for voltage at coil ( coil terminal 1 and terminal 2 ) 0. Coil terminal 1 to ground 277, Coil terminal 2 to ground 277. Check the continuity of the wires all good. Any help would be great

[Hrdworkingacguy]

LoL seriously...He has power to the contactor, just not a complete circuit.

[timebuilder]

Pretty hard for a contactor to pull in with no potential on the coil.

He has power, but he was using "ground" for that check.

One side (the neutral) of the coil is not connected somewhere, so he can't read across the coil.

[timebuilder]

Every other switch within the circuits are closed , APS, manual and auto thermal cutout, and stage 2 and 3 heater contactors are closed and heating. those are all that is there.

Have you found the solution yet, or are you stumped? I can give you my number.