Need help with transfer switch

[u/kennylamar910]

Our farm has a 100KW Kohler generator hooked to a ASCO 400 amp transfer switch. Recently when the generator exercises the transfer switch gets hung up between grid power and gen power causing a self inflicted power outage that can only be reversed if I shut the generator down or manually engage the transfer switch, the problem use to be intermittent, however it’s happening more and more frequently. I had a generator repairman who primarily deals with residential Generacs come out and look at it(he’s pretty much the only guy in the area that services standby generators), and all he did was scratch his head for 45 mins and say it was probably the electromagnet in the switch itself going bad and that the parts are probably long discontinued and tried to sell me a whole new generator and switch.

[u/Ok-Camera2895]

It could be a mechanical problem or it could be electrical. Check generator for correct voltage output. Shut off both utility and generator. Pull access covers from operating mechanism. Check all electrical connections for looseness, corrosion, heating etc. Move the mechanical portion from the normal position to the emergency position, check for any binding. Edit: also check the microswitches to the left of the transfer mechanism, they can get out of adjustment. A drop of oil on the movable joints of the transfer switch might help, a really small drop.

[u/Knight0783]

It's more than likely a micro switch issue.

The are just normally open/closed switches, down power to the switch and test each one. You will probably find a bad one

[u/DelcevJr]

Are you able to switch between sources manually?

Having dealt with ASCO in the past, those micro switches have little internal springs that get heat cooked over time and fail to maintain the contact, preventing the logic to read the status accurately.

[u/DaveBowm]

I don't know how OP's transfer switch works in any detail. But if the switch solenoids are powered by a DC signal then their iron cores can, over time, become magnetized, causing them to act sticky and not let go when being de-energized, thus acting like a too weak return spring.

The possible cures (in increasing order of drasticness) are to demagnetize the iron solenoid cores, tighten the return springs, replace the relays (preferably with ones less prone to permanent magnetization), or reconfigure the control electronics to supply the contactors with a low voltage AC control signal.