Hamworthy 4s12 control panel wiring question

[heydiver]

I'm new here and have a problem with a Hamworthy compressor console with under 200 hours, I bought on Ebay. The fire department that sold it said they couldn't keep the contactor engaged and got a new compressor. I bypassed the control circuits, hooked the power to the motor direct and found the compressor built up to pressure ok. It appears to have the safety switches for pressure, temperature, oil pressure and drains intact. It has a 230v 7.5hp single phase motor and the contactor has a 230v coil. All wiring is intact but for a single contactor coil wire. One leg of the coil is attached to one leg of the 230v live contactor input, and the other is not attached to anything, having a short piece of wire on it with some insulation off the end - it being attached to something in the control circuit in the past. Is there anyone familiar with the wiring that could point me in a direction to where the wire would go? I have pictures but don't have permission to post them yet.

 

[frogman62]

heydiver,
Do you know who assembled/manufactured the unit -- Eagle, American Bristol, OR ?????
One coil wire must connect to L2. Between L1 and the other coil wire are several safety switches - pressure switch, low oil level switch, high temperature switch and the ON contactor.
The three safety switches are "normally closed" switches and "OPEN" when pressure for shut off is reached OR oil level is low OR compressor gets too hot. Any one of the 3 conditions breaks the circuit and the electrical contactor "coil" loses power and the unit stops. These three switches are usually connected in series so anyone that "opens" causes the unit to shut down.
From what you described with a short wire to one side of the coil -- I would suspect the wire that is loose should be connected to L2.
If you need a better description, you can send a couple of pictures to me at my home email address
<jlshelden@sbcglobal.net>
Jim Shelden
316-992-0505

---------- Post added April 26th, 2014 at 05:10 PM ----------

Rick, I have looked at the pictures and with some discussion I think I can solve your problem The answer below has some incorrect information which we can clear up with a phone call. What is your phone# and I will call you. Send to my personal email address so it doesn't show up in scubaboard
Jim

heydiver,
Do you know who assembled/manufactured the unit -- Eagle, American Bristol, OR ?????
One coil wire must connect to L2. Between L1 and the other coil wire are several safety switches - pressure switch, low oil level switch, high temperature switch and the ON contactor.
The three safety switches are "normally closed" switches and "OPEN" when pressure for shut off is reached OR oil level is low OR compressor gets too hot. Any one of the 3 conditions breaks the circuit and the electrical contactor "coil" loses power and the unit stops. These three switches are usually connected in series so anyone that "opens" causes the unit to shut down.
From what you described with a short wire to one side of the coil -- I would suspect the wire that is loose should be connected to L2.
If you need a better description, you can send a couple of pictures to me at my home email address
<jlshelden@sbcglobal.net>
Jim Shelden
316-992-0505

 

[heydiver]

Great help Jim. Your explanation got it running fine. I'm going to think about changing the 230 contactor coil to 120 so not to have a live leg. Can't think of a downside.

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