The Motor-Protective Circuit Breaker Trips Immediately When The Power Supply Is Switched On; The Motor-Protective Circuit Breaker Trips Occasionally; The Motor-Protective Circuit Breaker Has Not Tripped, But The Motor Does Not Run - Grundfos MTR Montage- Und Betriebsanleitung

10.2 The motor-protective circuit breaker trips immediately when the power supply is
switched on
Cause
A fuse is blown or the motor-protective circuit breaker
has tripped.
The contacts in the motor-protective circuit breaker
are faulty.
The cable connection is loose or faulty.
The motor winding is defective.
The pump is mechanically blocked.
The overload setting for the motor-protective circuit
breaker is too low.

10.3 The motor-protective circuit breaker trips occasionally

Cause
The overload setting for the motor-protective circuit
breaker is too low.
The voltage is low at peak times.

10.4 The motor-protective circuit breaker has not tripped, but the motor does not run

Cause
Power supply failure.
One or more fuses are blown.
The thermal protection has tripped.
The main contacts in the motor-protective circuit
breaker are not making contact, or the coil is faulty.
The control circuit is defective.
Remedy
Replace the fuse or reset the motor-protective 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.
Remedy
Set the motor-protective circuit breaker correctly.
Ensure a constant power supply.
Remedy
Connect the power supply.
Replace the fuses.
Reactivate the thermal protection.
Replace the contacts or the magnetic coil.
Repair the control circuit.
19