Emerson Damcos, Service Manual

Page: 49 / 144

Damcos LPU: Troubleshooting Guide LPU Service Manual
February 2017 SM 8000-100-01 Ed 04
49
Motor not running and is hot
Action: Check that electrical connections to motor and capacitor are OK! Open bypass to release possible
pressure on pump and try to run the motor with opened bypass.
Then if: • Motor is running, but stops when bypass is closed.
Incorrectly connected motor or fault on motor or wires.
– Low supply voltage.
– Defective flow reducing valve, see “Motor ”diving” in RPM in end position ” on page 63.
• Motor is not running at all, even though bypass is opened.
– Disconnect current to LPU for measurement of resistance from N to CL and from N to OP on
printed circuit board (the easiest way is to disconnect the capacitor). Resistance must be
15

. The capacitor can on rare occasions be defective.
If connections and resistance are OK, the pump has stuck. New pump set is then mounted,
see “Replace Pump in LPU” on page 93. Reason for defective pump should be found, e.g.
insufficient quantity of oil, no stop of motor, impurities in oil etc.
Note! For LPU-Ex the temperature cut-off box might have interrupted power to motor due to too
high motor temperature. If this is the case the motor needs time to cool down, then 24 V
to LPU-Ex is interrupted for 10 seconds and LPU-Ex should be ready to run again.
Motor not running and is Cold
Action: • Check that there is 220 - 230 V AC over “N” and “open” or “close”, respectively when trying to
operate.
• Check that electrical connections to motor are OK. If the black wire is not connected, motor can-
not run.
• Dismount the motor wires. Check the resistance on the printed circuit board from “N” to the
centre motor wire, and from “open” and “close”, respectively to the two other motor connec-
tions. There must not be a measurable resistance.
• Check the resistance in the motor itself, there must be approximately 15

. between the black
wire and each of the others. If the resistance differs widely, the motor is to be replaced.
Note! For LPU-Ex the temperature cut-off box will interrupt power to motor if 24 V is not present
or bounces when it is connected.