calling john t, o wizard of electrons...help!!

john, my spray booth went down today at the shop, 220v 3phase, runs two 5 hp 3 ph motors, one for the main burner , one for the exhaust stack. popped a 60 amp fuse on the 220 side. both 110 legs were good. exhaust stack motor got hot. replaced all 3 fuses, main burner and blower will start but not exhaust stack. motor on stack is still good. looks like maybe the contactor is the problem. it will not close. have 110 v power at both top terminals behind the 3 ph feeds, see pictures. i can manually close the contactor switch and the exhaust fan will run. any way to test the contactor??? pay no attention to the shaved off paint stick stuck in the contactor to close the switch, but cars have to get painted and delivered. any thoughts? called my booth guy, but he cant get here for a few days and i gotta get this thing running.
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Did you reset your overload switch. Could be a bad coil or overload unit, if it does not reset it will not pick up the coil to close the contacts, have had many go bad, have saved a few by remelting the solder and letting it cool then resetting the overload.

I believe your contactor is bad. If they are similar, swap them between motors and see if the stack fan runs but the burner does not. If the case, it is the contactor. Ohm out the pull in coil of the contactor, it should conduct, if Infinite resistance, it is toast. JimN

thanks jim, i will try that tomorrow. any idea why it would toast the fuse on the high side of the 3 ph leg? maybe burned contacts on that leg in the contactor?

Hi Glenn,

As you know, I don't offer repair advice via internet on gas/fuel/electrical as someone will surly die.

Your relay/contactor is most likely good and is in the "SAFETY" part of the circuit where any of 3 too 10 components could have failed causing a no start condition.

T_Bone

I see an overload switch in the lower section of the starter/contactor assembly. Push that, if you feel a click, it just reset. These are typically wired in the controls to the coil circuit. Still doesn't answer what blew the fuses, but ??

heres the update. got the overload switches reset on the contactors, check over the wiring best i could, and now the contactors are working properly. so far it seems like all is running. could not find any reason why it blew the 60 amp fuse on the high side, no burned wires, no excessive current draw on either motor. did find out this morning the power company was replacing lines on the north end of town yesterday, wonder if that could have caused the problem?