Thermoking KD II SR will not run under standby power

[Timberwolf17044]

Having trouble with a KD II SR, I can't get this unit to function under standby power. Voltage is 230 volt 3 phase and rotation is correct. Engaging the contactor manually will run the motor so the motor is good. I have checked oil pressure switch and it is good. It appears as if there is no voltage being provided to engage the contactor. I even tried swapping out the main pc board with no improvement. Any additional thoughts on this is appreciated.

[Timberwolf17044]

Wow! 24 views and no one has a clue to offer. Surely someone has had this issue before?

[chillerman2006]

Hi Timberwolf

without a schematic its hard to help you and even more so with the limited info you have supplied

you say you have checked the oil pressure switch, is this earthing the standby relay?

does the relay have a live feed ?

Is there a switched live present at the relay ?

Is the stanby relay energising ?

If not have you removed and checked the relay operates ?

Have you checked thermostat operates ok ?

Does the unit run ok in diesel mode ?

This is an old unit with fairly basic wiring which you should be able to back trace from the contactor

[Timberwolf17044]

Working from last to first...
Unit runs fine in diesel mode.
Thermostat operates correctly.
Relay's are sealed components on the main pc board.
There is no standby relay to my knowledge unless you are referring to the electric motor contactor in which case no it does not operate as it is not getting the required 12 VDC to engage the coil.
When I manually engage the motor contactor the motor will run. This indicates to me that the overloads are functioning properly. There is a NC switch also on the overload with is operating correctly dependent upon the state of the overload relay coil, (energized or not).
The oil pressure switch is simply a safety device that tells the main pc not to run the standby motor if that switch is open (indicating a positive oil pressure, meaning the engine is running).
Referring to the Oil display on the control panel it shows "----" when the unit is running in diesel mode, and "0" when the unit is off, since it is a simple mechanical switch it does not have the capability to derive an actual oil pressure reading electronically, all that said I am assuming that the ---- and 0 indicators on the display are proper and the switch is functioning.
Lastly, as I have been pondering this away from the job site it has occurred to me that the phase correction/reversal module could be a culprit however I do not know its relationship to the main pc. There is an icon on the control panel when the unit is plugged in showing electric power is provided, this I assume has to be provided by the phase correction/reversal module. But could there also be something defective in that module preventing the necessary 12VDC from being provided to the motor contactor via the PC board?

[chillerman2006]

when the engine is not running the oil pressure switch is the earth for the stanby relay

when the engine runs the oil pressure opens the contacts in the switch removing the earth to the standby relay

you can remove this relay and give it an earth and live to check it operates

with the relay removed you can then check the relay socket for live feed and switched live and earth

this relay is the 12vdc supply to pull in the contactor

its bed for me now bud, hope you get it sorted

[MRW]

are you getting any fault codes? have seena problem with phase modules

[Timberwolf17044]

The only fault code is 31 or 36 Electric Motor Failed to Run

[chillerman2006]

[QUOTE=Timberwolf17044;235842]When I manually engage the motor contactor the motor will run. This indicates to me that the overloads are functioning properly. [QUOTE]

Well it does not to me, as the overloads are part of the control circuit which you have just over ridden by maually pushing the conatctor in

[The Fox]

try the phase correction module, top right on pcb. we have lots of prblems with them. 9 times out of ten its the problem

[Timberwolf17044]

Update:
I've determined that it is an oil pressure sensor that is defective. Is there anyway to bypass the sensor so that I can run the unit on standby other then providing a separate ground to the motor contactor?

[cadwaladr]

if you have control of this unit,provide the ground until you get a new oil pressure switch/sensor,have you changed the oil and filters you could have a sludgey oil problem use a oil flushing agent to clear residue.

[Reeferdoc]

i wouldnt thnk it was the phase sensor if there is standby icon on cab command. I would switch out oil pressure switch then if not that pull wires off contactor coil and supply 12 volts to see if contactor engages with good 12 volt power supply. alot of times contactors have good continuity through but coils which pull them in can be bad. if still not that swap out micro.

[djbe]

i wouldnt thnk it was the phase sensor if there is standby icon on cab command. I would switch out oil pressure switch then if not that pull wires off contactor coil and supply 12 volts to see if contactor engages with good 12 volt power supply. alot of times contactors have good continuity through but coils which pull them in can be bad. if still not that swap out micro.

I have seen it, standby icon but phase sensor faulty.

[symon22]

try the continuity through the deisel electric switch. the wire through to the o/p switch is 20a. 9 times out of ten it will be the deisel elec switch...