Grundfos MTA 110H-180, Installation And Operating Instructions Manual

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7
English (US)
8. Fault finding
Warning
Before starting fault finding, switch off the power supply.
Make sure that the power supply cannot be accidentally switched on.
Fault Cause Remedy
1. Motor does not
run when power
supply is
switched on. a) Supply failure. Connect the power supply.
b) Fuses are blown. Replace the fuses.
c) Motor-protective circuit breaker
has tripped. Reactivate the motor protection.
d) Main contacts in motor-protective
circuit breaker are not making
contact or the coil is faulty. Replace the contacts or the
magnetic coil.
e) Control circuit is defective. Repair the control circuit.
f) Motor is defective. Replace the pump.
2. Motor-protective
circuit breaker
trips
immediately
when power
supply is
switched on. a) Fuse on one phase is blown. Replace the fuse.
b) Contacts in motor-protective
circuit breaker are faulty. Replace the contacts in the
motor-protective circuit breaker.
c) Cable connection is loose or
faulty. Fasten or replace the cable
connection.
d) Motor winding is defective. Replace the pump.
e) Pump mechanically blocked. Remove the mechanical blocking of
the pump.
f) Overload setting is too low. Set the motor-protective circuit
breaker correctly.
3. Motor-protective
circuit breaker
trips
occasionally. a) Overload setting is too low. Set the motor-protective circuit
breaker correctly.
b) Low voltage at peak times. Check the power supply.
4. Motor-protective
circuit breaker
has not tripped,
but the pump
does not run. a) Cause may be the same as under
1 a), 1 b), 1 d) and 1 e). See remedy for 1 a), 1 b), 1 d) and
1 e).
5. Pump runs, but
gives no liquid,
or pump
capacity is not
constant. a) Pump inlet partly blocked by
impurities. Clean the inlet.
b) Liquid level in tank is too low. Increase the liquid level.
c) Pump rotates in the wrong
direction. Change the direction of rotation of
the motor by switching any two of
the phases.
d) Pumped liquid of too high density
or viscosity Change to a liquid of lower density
or viscosity.
e) Impeller wearing on foreign
objects Remove foreign objects from the
pump housing