Grundfos SLV.65 Bedienungsanleitung Seite 24

11. Fault finding
Warning
Before attempting to diagnose any fault,
make sure that the fuses have been
removed or the mains switch has been
switched off. Make sure that the power
supply cannot be accidentally switched on.
All rotating parts must have stopped
moving.
Fault
1. The motor does not start.
The fuses blow or the
motor-protective circuit
breaker trips out
immediately.
Caution: Do not start again!
2. The pump operates, but the
motor-protective circuit
breaker trips out after a
short while.
3. The pump's thermal switch
trips out after the pump has
been operating for some
time.
4. The pump operates at
below-standard
performance and power
consumption.
5. The pump operates, but
delivers no liquid.
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Cause
a) Supply failure, short-circuit or
earth-leakage fault in the cable
or motor winding.
b) The fuses blow due to use of
wrong type of fuse.
c) The impeller is blocked by
impurities.
d) Air bells, float switches or
electrodes out of adjustment or
defective.
a) Low setting of the thermal relay
in the motor-protective circuit
breaker.
b) Increased current consumption
due to large voltage drop.
c) The impeller is blocked by
impurities. Increased current
consumption in all three
phases.
d) The impeller clearance is
incorrect.
a) Too high liquid temperature.
b) Too high liquid viscosity.
c) Wrong electrical connection (If
the pump is star-connected to a
delta connection, the result will
be very low undervoltage).
a) The impeller is blocked by
impurities.
b) Wrong direction of rotation.
a) The outlet valve is closed or
blocked.
b) The non-return valve is
blocked.
c) Air in the pump.
Warning
All regulations applying to pumps installed
in potentially explosive environments must
be observed.
Make sure that no work is carried out in
potentially explosive atmosphere.
Remedy
Have the cable and motor checked
and repaired by a qualified
electrician.
Install fuses of the correct type.
Clean the impeller.
Readjust or replace the air bells,
float switches or electrodes.
Set the relay in accordance with the
specifications on the nameplate.
Measure the voltage between two
motor phases. Tolerance: - 10 %/+
6 %. Reestablish correct voltage
supply.
Clean the impeller.
Readjust the impeller. See section
10.2 Adjusting the impeller
clearance, fig. 12.
Reduce the liquid temperature.
Dilute the liquid.
Check and correct the electrical
installation.
Clean the impeller.
Check the direction of rotation and
possibly interchange any two
phases of the incoming supply
cable. See section
rotation.
Check the outlet valve and possibly
open and/or clean.
Clean the non-return valve.
Vent the pump.
9.3 Direction of