Fault Correction - Grundfos DPK Series Installation And Operating Instructions Manual

15. Fault correction

Warning
Before starting work on the pump, make sure that the fuses have been removed or the mains switch
has been switched to off. It must be ensured that the power supply cannot be accidentally switched
on.
All rotating parts must have stopped moving.
For pumps with sensor, start fault finding by checking the status on the GU01 or GU02 front panel.
Note
See installation and operating instructions for GU01 or GU02.
Fault
Motor does not start,
fuses blow or motor
protector trips out
immediately.
Caution: Do not try to
start again.
Pump operates, but
motor protector trips out
after a short while.
The thermal switch of
the pump trips out after
a short while.
Pump operates at
below-standard
performance and power
consumption.
Pump operates, but
gives no liquid.
Pump clogged.
Cause
1. Supply failure; short-circuit;
earth-leakage fault in cable or
motor winding.
2. Fuses blow due to use of wrong
type of fuse.
3. Impeller blocked by impurities.
4. Level pickup, float switch or
electrode out of adjustment or
defective.
5. Motor phase malfunction
1. Low setting of thermal relay in
motor protector.
2. Increased current consumption
due to large voltage drop.
3. Impeller blocked by impurities.
4. Wrong direction of rotation.
1. Too high liquid temperature.
Inadequate cooling.
2. Too high viscosity of the
pumped liquid.
3. Fault in the electrical
connection.
(Y-connection of pump to
D-connection results in
considerable undervoltage)
1. Impeller blocked by impurities.
2. Wrong direction of rotation.
1. Air in pump.
2. Outlet valve closed or blocked.
3. Non-return valve blocked.
1. The liquid contains large
particles.
2. A float layer has formed on the
surface.
Remedy
Have the cable and motor checked and
repaired by a qualified electrician.
Fit fuses of the correct type.
Clean the impeller.
Check the level pickups, float switches or
electrodes.
Inspect motor and connections.
Set the relay in accordance with the
specifications on the pump nameplate.
Measure the voltage between two motor
phases. Tolerance: - 5 %/+ 5 %.
Clean the impeller.
Check the direction of rotation and possibly
interchange any two phases in the power
supply. See section 12.1 Direction of
rotation.
Improve cooling or lower the liquid
temperature.
Dilute the pumped liquid.
Check and correct the electrical connection.
Clean the impeller.
Check the direction of rotation and possibly
interchange any two phases in the power
supply. See section 12.1 Direction of
rotation.
Vent the pump twice.
Check the outlet valve and possibly open
and/or clean.
Clean the non-return valve.
Select a pump with a larger size of passage.
Install a mixer in the tank.
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