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12
chapter discard.fm Page 12 Tuesday, June 7, 2011 9:29 PM
Possible causes
1. Pressure switch is not prop-
erly adjusted or is defective.
2. Level control is not properly
set or is defective.
3. Insufficient air charging or
leaking tank or piping.
4. Tank is too small.
5. Pump is oversized.
1. Low voltage.
2. Starter overloads are set
too low.
3. Three phase current is
imbalanced.
4. Motor is shorted or
grounded.
5. Wiring or connections are
faulty.
6. Pump is bound.
7. Defective capacitor (single-
phase motors).
8. Motor overloads at higher
ambient temperature than
motor.
How to check
Check pressure setting on
switch and operation. Check
voltage across closed contacts.
Check setting and operation.
Pump air into tank or dia-
phragm chamber. Check dia-
phragm for leak. Check tank
and piping for leaks with soap
and water solution. Check air
to water volume.
Check tank size and air volume
in tank. Tank volume should
be approximately 10 gallons
for each gpm of pump capac-
ity. The normal air volume is
2/3 of the total tank volume at
the pump cut-in pressure.
Install pressure gauges on or
near pump suction and dis-
charge ports. Start and run
pump under normal condi-
tions, record gauge readings.
Check voltage at starter panel
and motor.
Cycle pump and measure
amperage.
Check current draw on each
lead to the motor.
Turn off power and dissconnect
wiring. Measure the lead-to-
lead resistance with an ohm
meter (R x 1). Measure lead-
to-ground values with an ohm
meter (R x 100K) or a mega-
ohm meter. Record values.
Check proper wiring and loose
terminals.
Turn off power and manually
rotate pump shaft.
Turn off the power and
discharge the capacitor. Check
with ohm meter (R x 100K).
Use a thermometer to check
the
ambient
temperature
near the overloads and motor.
Record these values.
Fault
C. Pump cycles too much
D. Fuses blow or circuit
breakers or heaters trip
Troubleshooting Chart
How to fix
Readjust switch or replace if
defective.
Readjust setting (refer to level
control manufacturer’s data).
Replace if defective.
Replace as necessary.
Replace tank with one of cor-
rect size.
Convert PSI to feet (Measured
PSI x 2.31 ft. / PSI = ____ft.)
Refer to the specific pump
curve for that model. Ensure
that total head is sufficient
to limit pump delivery within
its design flow range. Throttle
pump discharge flow is neces-
sary.
If voltage varies more than ±
10%, contact power company.
Check wire sizing.
Increase heater size or adjust
trip setting to a maximum of
motor nameplate (full load)
current.
Must be within ± 5%. If not,
check motor and wiring.
Rotating all leads may elimi-
nate this problem.
If an open or grounded wind-
ing is found, remove the motor,
repair and/or replace.
Tighten loose terminals. Re-
place damaged wire.
If shaft does not rotate eas-
ily, check coupling setting and
adjust as necessary. If shaft
rotation is still tight, remove
pump and inspect. Disass-
emble and repair.
When the meter is connected
to the capacitor, the needle
should jump toward “0” ohms
and slowly drift back to infin-
ity. Replace if defective.
If ambient temperature at
motor is lower than at the
overloads, especially where
temperature at overloads is
above 104°F ambient compen-
sated heaters should replace
standard heaters.
