The Pump Operates But The Motor Protector Trips After A Short While; The Thermal Switch Of The Pump Trips After A Short While; The Pump Operates At Below-Standard Performance And Power Consumption; The Pump Operates, But Gives No Liquid - Grundfos DPK Series Installation And Operating Instructions Manual

9.2 The pump operates but the motor
protector trips after a short while
Cause
Low setting of the
thermal relay in the
motor protector.
Increased current
consumption due to
large voltage drop.
The impeller is blocked
by impurities.
The direction of rotation
is wrong.
9.3 The thermal switch of the pump trips
after a short while
Cause
The liquid temperature
is too high. Inadequate
cooling.
The viscosity of the
pumped liquid is too
high.
Fault in the electrical
connection.
9.4 The pump operates at below-standard
performance and power consumption
Cause
The impeller is blocked
by impurities.
The direction of rotation
is wrong.
22
Remedy
• Set the relay according
to the specifications on
the pump nameplate.
• Measure the voltage
between two motor
phases. Tolerance: ± 5
%.
• Clean the impeller.
• Check the direction of
rotation and possibly
interchange any two
phases in the power
supply. See section
Direction of rotation.
Remedy
• Improve cooling or
lower the liquid
temperature.
• Dilute the pumped
liquid.
• Check and correct the
electrical
connection (Y-
connection of pump to
D-connection results in
considerable
undervoltage).
Remedy
• Clean the impeller.
• Check the direction of
rotation and possibly
interchange any two
phases in the power
supply. See section
Direction of rotation.

9.5 The pump operates, but gives no liquid

Cause
There is air in the pump. •
The outlet valve is
closed or blocked.
The non-return valve is
blocked.

9.6 The pump is clogged

Cause
The liquid contains large
particles.
A float layer has formed
on the surface.

10. Technical data

10.1 Operating conditions

Operating mode
Liquid temperature
Maximum number of starts
per hour
2)
Ambient temperature
Maximum density of the
medium
pH
3)
Maximum installation depth
Maximum operating pressure 5.7 bar
Maximum operating altitude
2) If the pump is not completely submerged.
3) For DPK.V, maximum installation depth is 20m.
Related information
6.2 Operating modes
Remedy
Vent the pump twice.
• Check the outlet valve
and open and/or clean
it if necessary.
• Clean the non-return
valve.
Remedy
• Select a pump with a
larger size of passage.
• Install a mixer in the
pit.
S1, S3
0-40 °C
15 (19-22 kW range)
30 (0.75 - 15 kW range)
0-40 °C
1000 kg/m³
4-10
25 m
2000 m above sea level