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17. Diagnosing specific problems
Warning
Before removing the terminal box cover and before removing/dismantling the pump, make sure that the power
supply has been switched off and that it cannot be accidentally switched on.
Problem Possible cause Remedy
1. The pump does not run. a) No power to motor. Check voltage to motor terminal box. If no
voltage to motor, check starter panel for tripped
circuits and reset circuits.
b) Fuses blown or circuit breaker tripped. Turn off power and remove fuses. Check for
continuity with ohmmeter. Replace blown fuses
or reset circuit breaker. If new fuses blow or
circuit breaker trips, the electrical installation,
motor and wires must be checked.
c) Motor starter overload protection burned or tripped
out.
Check for voltage on line and load side of
starter. Replace or reset burned motor
protection. Inspect starter for other damage.
If protection trips again, check the supply
voltage and starter holding coil.
d) Starter does not energize. Energize control circuit and check for voltage to
the holding coil. If no voltage, check control
circuit fuses. If voltage, check holding coil for
short circuits. Replace bad coil.
e) Defective control devices. Check that all safety and pressure switches
function correctly. Inspect contacts in control
devices. Replace worn or defective parts or
control devices.
f) Motor is defective. Turn off power and disconnect wiring.
Measure the lead-to-lead resistances with
ohmmeter (RX-1). Measure lead-to-ground
values with ohmmeter (RX-100K).
Record measured values. If an open or
grounded winding is found, remove motor and
repair or replace it.
g) Defective capacitor (single-phase motors). Turn off power and discharge capacitor.
Check with ohmmeter (RX-100K). When the
meter is connected to the capacitor, the needle
should jump towards 0 ohms and slowly drift
back to infinity (h). Replace capacitor if
defective.
h) Pump is blocked or seized. Turn off power and manually rotate pump shaft.
If shaft does not rotate easily, check coupling
setting and adjust as necessary. If shaft rotation
is still tight, remove pump and inspect.
Disassemble and repair the pump.
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