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7.0
The normal temperature rise for standard motors is 40°C above ambient temperature and, thus, it might appear
that the motor is operating at a higher than normal temperature. This situation is normal.
As a precaution against motor overheating, it is recommended that the pump be located where adequate
ventilation is available, It is also recommended that a MOTOR STARTER WITH THE PROPER OVERLOAD
PROTECTION BE SUPPLIED AS AN ADDITIONAL SAFETY DEVICE.
SYMPTOMS
1. Pump Motor Will Not
Operate.
2. Pump Does Not Deliver
Rated Capacity
3. Pump delivers
erratically.
4. Motor overheats thermal
overload activates,
5. Noisy Operation
5.1. In Pump
5.2. In Gear Reducer
MOTOR OPERATING CONDITIONS
TROUBLESHOOTING CHART
CAUSES
A. Blown Fuse.
B. Open thermal overload device in
starter.
C. Low liquid level in tank (where low
level cut-off is used).
D. Broken wire.
E. Low voltage.
A. Starved suction.
B. Leaky suction piping.
C. Excessive suction lift.
D. Liquid too close to boiling point.
E. Worn or dirty valves or seats, or
both
F. Viscosity of liquid too high
G. Low discharge pressure
A. Leaky suction line.
B. Worn or dirty valves or seats, or
both.
C. Excessive excursion of ball valves
from seats (indicated by ball chatter).
D. Insufficient suction pressure
E. Liquid too close to boiling point,
F Leaky system relief valve.
A. Power supply does not match motor.
B. Overload caused by operating pump
beyond rated capacity
A. Pump Valves.
A. Pounding noise at high discharge
pressure
SECTION IV
SECTION V
REMEDIES
Check for short circuit or overload
Reset.
Fill tank.
Locate and repair.
Check for too light wiring.
Look for blockage in suction line.
Replace suction piping with larger size.
Pressure test, repair or replace defective piping.
Rearrange equipment location to reduce suction lift.
Lower temperature or increase suction pressure slightly.
Clean or replace valve assembly.
1.
Reduce viscosity by heating or other means
2.
Increase size of suction piping
3.
Increase suction pressure slightly
A minimum discharge pressure of 25 psi is required to
insure proper capacity control
Repair or replace piping.
Clean or replace valve assembly.
Increase backpressure.
Increase suction pressure.
Raise tank level.
Reduce temperature or raise suction pressure.
Repair or replace relief valve
Check power supply against motor nameplate data.
Check operating pressure against pump manufacturer
data plate maximum rating
Valves must move to open and close, and they will make
a clicking noise as they operate. These noises are
sometimes amplified by natural resonances in piping
system. They are usually indications of normal valve
functioning.
Fluid compressibility causes reversal of load on gears at
end of pressure stroke, Not considered detrimental.
21
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