Danfoss APP W HC Series, Operation Manual

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Service guide | Trouble shooting guide for APP, APP S and APP S 674 pumps
66 | © Danfoss | DCS (im) | 2022 .01 180R9410 | AQ282628894589en-000801 | IOM APP W HC 15-30 Pumps
Cause Remedy Comments
3.1 Too high outlet pressure from pump 3 .1 .1 Check fluid salinity .
3 .1 .2 Check temperature .
3 .1 .3 Check pressure drop across RO membrane .
Pump conditions may change (more salt, lower
water temperature or scaling of RO membrane)
causing higher pressure, resulting in higher
motor torque .
3.2 Pump starts against pressure
3 .2 .1 Check that electric motor is correctly sized .
3 .2 .2 Check internal parts (see item 2 .1) .
3 .2 .3 Systems with more than one electric
motor installed:
Start motors simultaneously .
Pumps run in parallel with cascade start, may
switch off the motor relay due to too high
torque caused by high outlet pressure .
3.3 Constant torque
3 .3 .1 Please contact Danfoss High Pressure
Pumps sales office .
If the electric motor is too small for the APP, APP S
or APP S 674 pump, it cannot provide sufficient
torque .
3.4 Water pump damage
3 .4 .1 Dismantle pump and check for wear . Too heavy damage in the pump will increase
friction causing a high torque (see item 6,
Typical signs of wear) .
3. High torque on electric motor