Fault Finding - Grundfos MTA 30 Instrucciones De Instalación Y Funcionamiento

9. Fault finding

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