Grundfos MTD Montage- Und Betriebsanleitung Seite 10

Fault
1. Motor does not run
when the power
supply is switched
on.
2. Motor-protective
circuit breaker trips
immediately when
the power supply is
switched on.
3. Motor-protective
circuit breaker trips
occasionally.
4. Motor-protective
circuit breaker has
not tripped but the
pump does not run.
5. The pump runs but
gives no liquid, or
pump performance
is not constant.
6. Leakage in shaft
seal.
7. Noise.
10
Cause
a) Power supply failure.
b) The fuses are blown.
c) Motor-protective circuit breaker has
tripped.
d) The thermal protection has tripped.
e) The main contacts in the motor-
protective circuit breaker are not
making contact or the coil is faulty.
f) The control circuit is defective.
g) The motor is defective.
a) A fuse is blown or the automatic
circuit breaker has tripped.
b) The contacts in the motor-protective
circuit breaker are faulty.
c) The cable connection is loose or
faulty.
d) The motor winding is defective.
e) The pump is mechanically blocked.
f) Motor-protective circuit breaker
overload setting is too low.
a) Motor-protective circuit breaker
overload setting is too low.
b) Low voltage at peak times.
a) Check 1 a), b), d), e) and f).
a) The pump strainer is partly blocked
by impurities.
b) The liquid level in the tank is too low.
c) Pump draws in air.
d) The pump rotates in the wrong
direction.
e) The impeller is damaged.
a) Shaft seal is defective.
a) Cavitation.
b) Pump does not rotate freely (frictional
resistance) because of incorrect
pump shaft position.
c) A bearing is damaged.
d) The pump is running single phase.
e) Some parts have come loose.
Remedy
Connect the power supply.
Replace the fuses.
Reactivate the motor-protective
circuit breaker.
Reactivate the thermal protection.
Replace contacts or magnetic coil.
Repair the control circuit.
Replace the motor.
Replace the fuse or cut in the circuit
breaker.
Replace the motor-protective circuit
breaker contacts.
Fasten or replace the cable
connection.
Replace the motor.
Remove the mechanical blocking of
the pump.
Set the motor-protective circuit
breaker correctly.
Set the motor-protective circuit
breaker correctly.
Reestablish constant power supply.
Clean the strainer.
Increase the liquid level.
Check the inlet conditions.
Change the direction of rotation of the
motor by switching any two of the
phases.
Replace the impeller.
Replace the shaft seal.
Check the inlet conditions.
Adjust the pump shaft.
Replace the bearing.
Check the electrical conditions.
Check the installation conditions.