Grundfos MTR - 10.2 The motor-protective circuit breaker trips immediately when the power supply is switched on; 10.3 The motor-protective circuit breaker trips occasionally

10.2 The motor-protective circuit breaker trips immediately when the power supply is
switched on
Cause Remedy
A fuse is blown or the motor-protective circuit breaker
has tripped.
Replace the fuse or reset the motor-protective circuit
breaker
.
The contacts in the motor-protective circuit breaker
are faulty
.
Replace the motor-protective circuit breaker contacts.
The cable connection is loose or faulty. Fasten or replace the cable connection.
The motor winding is defective. Replace the motor.
The pump is mechanically blocked. Remove the mechanical blocking of the pump.
The overload setting for the motor-protective circuit
breaker is too low
.
Set the motor-protective circuit breaker correctly.
10.3 The motor-protective circuit breaker trips occasionally
Cause Remedy
The overload setting for the motor-protective circuit
breaker is too low
.
Set the motor-protective circuit breaker correctly.
The voltage is low at peak times. Ensure a constant power supply.
10.4 The motor-protective circuit breaker has not tripped, but the motor does not run
Cause Remedy
Power supply failure. Connect the power supply.
One or more fuses are blown. Replace the fuses.
The thermal protection has tripped. Reactivate the thermal protection.
The main contacts in the motor-protective circuit
breaker are not making contact, or the coil is faulty
.
Replace the contacts or the magnetic coil.
The control circuit is defective. Repair the control circuit.
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