Cause
Remedy
The self-holding function of the
contactor malfunctions.
Check:
• The contactor connections.
• The voltage in the control circuit in relation to the rated voltages
on the coil.
• The functioning of the stop-level regulator.
• Whether the voltage drop in the line at the starting surge causes
the contactor's self-holding malfunction.
If the problem persists, then contact a sales or authorized service representative.
Always state the serial number of the product, see
on page 12.
7.5 The pump runs but the motor protection trips
DANGER: Crush Hazard
Moving parts can entangle or crush. Always disconnect and lock out power before servicing
to prevent unexpected startup. Failure to do so could result in death or serious injury.
NOTICE:
Do NOT override the motor protection repeatedly if it has tripped. Doing so may result in
equipment damage.
Cause
Remedy
The motor protection is set too
low.
Set the motor protection according to the data plate and if applicable
the cable chart.
The impeller is difficult to rotate
by hand.
• Clean the impeller.
• Clean out the sump.
• Check the clearance between the propeller and the pump
housing.
The drive unit is not receiving full
voltage on all three phases.
• Check the fuses. Replace fuses that have tripped.
• If the fuses are intact, notify a certified electrician.
The phase currents vary, or they
are too high.
Contact a sales or authorized service representative.
The insulation between the
phases and ground in the stator is
defective.
1. Use an insulation tester. With a 1000 V DC megger, check that
the insulation between the phases and between any phase and
ground is > 5 megaohms.
2. If the insulation is less:
Contact a sales or authorized service representative.
The density of the pumped fluid is
too high.
Make sure that the maximum density is 1100 kg/m
3
(9.2 lb/US gal)
• Change the impeller, or
• Change to a more suitable pump.
• Contact a sales or authorized service representative.
There is a malfunction in the
overload protection.
Replace the overload protection.
Always state the serial number of the product, see
on page 12.
7 Troubleshooting
82
P7030, P7035, P7040 Installation, Operation, and Maintenance Manual
