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Page 20 F00633
Troubleshooting
Maintenance
Electrical Drive Pumps
CAUSE CORRECTIVE ACTION
I. ELECTRICAL
A. No voltage in power system Check phase-to-phase on line side of starter contactor.
Check circuit breaker or fuses.
B. No voltage on one phase Check phase voltage on line side of starter contactor. Isolate open circuit
(Three Phase Units) (circuit breaker, fuse, broken connections, etc.)
C. Low voltage at motor Running voltage across each leg of motor must be ±10% of nominal
voltage shown on nameplate.
D. Motor leads improperly grouped Refer to lead grouping diagram on motor nameplate.
for voltage
E. Control failure Check control device, starter contactor, H-O-A selector switch, etc.,
for malfunction.
F. Thermal overload switch open Check phase-to-phase on line side of starter contactor.
G. Installation failure Check motor or windings to ground with megohmmeter.
H. Open windings Check leg-to-leg with ohmmeter.
I. Frequency variation Check frequency of power system. Must be less than 5% variation from
motor nameplate rating.
II. MECHANICAL
A. Flow through pump completely or Locate and remove obstruction. Refer to Repair Instructions
partially obstructed for disassembly.
B. Wrong direction of rotation Reverse rotation of three phase motor by interchanging any two leads.
See manufacturer’s Instructions for reversing single phase motor.
C. Pump not primed Reprime. Inspect suction system for air leaks.
D. Internal leakage Check impeller for wear of controlled clearances (See Repair Instructions).
E. Loose parts Inspect. Repair.
F. Stuffing box not properly adjusted Adjust gland.
III. SYSTEM
A. Pressure required by system at design Compare pump pressure and flow rate against pump characteristic curve.
flow rate exceeds pressure rating of pump Check for closed or partially closed valve in discharge piping system.
Reduce system pressure requirement. Increase pressure capability of pump.
B. Obstruction in suction piping Locate and remove obstruction.
C. Pressure rating of pump exceeds pressure Compare pump pressure and flow rate against pump characteristic curve.
requirement of system at design flow rate Inspect discharge piping system for breaks, leaks, open by-pass valves, etc.
If necessary, reduce flow rate by partially closing discharge valve.
PROBABLE CAUSE
SYMPTOM GROUP I GROUP II GROUP III
ELECTRICAL MECHANICAL SYSTEM
ABC DE FGH I ABCDEFABC
Pump runs, but no water delivered X X X X
Not enough water delivered X X X X X X X X
Not enough pressure X X X X X X X X
Excessive vibration X X X X X X
Abnormal noise XXX XX XX
Pump stops X X X X X X X X
Overheating X X X X X X X X X