6-1
6. Troubleshooting
The following table lists causes of failures and their actions. In the event of a failure, however, you should
carefully investigate the problem and ask the vendor to carry out any actions that are not easy to take.
Problem
Cause (Reference page)
Action (Reference page)
Done by *
The pump does
not start.
Wiring is disconnected or broken. (3-4)
Check the wires and connections.
Repair or replace.
Vendor
The power fuse is blown.
Replace it with an appropriate fuse.
User
Tripping of the thermal relay
Check the thermal relay.
User
Poor connection or contact of power wires
(3-4)
Check the wires and connections.
Vendor
The power voltage is too low. (2-2)
Check the power voltage.
Contact the power company.
User
The motor has failed.
(e.g. broken wire of
the stator winding)
Repair at vendor's shop.
Contact the vendor because disassembly
and inspection are required.
Vendor
Foreign matter is caught in the impeller.
Disassemble, clean, and repair.
Contact the vendor because disassembly
and inspection are required.
Vendor
The bearing is rusty. (5-1)
Replace the bearing. (5-1)
Contact the vendor because disassembly
and inspection are required.
Vendor
Overload and
overcurrent of the
motor
The rotation speed is too high.
Check with the tachometer.
User
The voltage is too high or too low.(2-2)
Check the power voltage.
Contact the power company.
User
Fluctuation of the voltage
A 50Hz pump is run in the 60Hz power
zone.
Check the nameplate. (2-3)
User
The stator winding is broken, shorted, or
grounded.
Contact the vendor because disassembly
and inspection are required.
Vendor
The stator and rotor are in contact due to
wear of the bearing. (5-1)
Replace the bearing. (5-1)
Contact the vendor because disassembly
and inspection are required.
Vendor
The motor is running in open-phase
condition.
Check the wiring.
User
The dynamic viscosity of the pumping liquid
is too high.
Use a liquid with low dynamic viscosity.
User
The discharge rate is high.
Throttle the sluice valve to adjust the rate
as per the specifications.
User
A rotating part is in contact with another
part.
Contact the vendor because disassembly
and inspection are required.
Vendor
The pump starts,
but cannot
achieve the
specified
discharge rate
and the specified
head.
The pumping liquid contains many bubbles. Prevent the formation and suction of
bubbles.
User
The rotation direction is reverse. (4-1)
Correct the wiring so that the motor rotates
in normal direction. (4-1)
User
The piping loss is high.
Check the diameter, route and length of the
pipes.
User
The piping is clogged with foreign matter.
Check and clean the piping.
User
The impeller is worn.
Replace the impeller.
Contact the vendor because disassembly
and inspection are required.
Vendor
Foreign matter is accumulated in the
impeller and in the casing.
Remove the foreign matter, and check the
connections.
Contact the vendor because disassembly
and inspection are required.
Vendor
The impeller is rusty.
Check the liquid used.
User