Davey 4 Submersible Borehole Pumps SERIES J - Manual (Page 7)

7
Operation and maintenance
While Davey submersible pumps do not require regular maintenance, it is a good practice to monitor the conditions and
performance of the pump and motor. This diagnosis may be carried out by checking the maximum pressure (shut valve
for a very short period) generated by the pump, and by checking the amperage draw of the motor at standard duty flow
rate.
Both these figures should be compared to pressures and current draws recorded when the unit was initially installed. Any
reduction in pressure may indicate wear in the pump, while any increase in motor current indicates a possible overload
condition. Consult the pump service chart for further diagnosis of possible causes.
The pump must not be operated with the delivery valve shut off (closed head) for more than a few sec-
onds otherwise the motor will overheat, possibly causing permanent damage, not covered by guaran-
tee
Pump service chart
The following chart offers a means of diagnosing general pump problems.
Problem Possible Causes
1. Overload protector trips - Control box or thermals in the sun or near heat source.
- Incorrect thermals or control box fitted.
- Low line voltage.
- Phase failure (3 phase only).
- Faulty motor
2. No water delivered - Water level in bore too low.
- Check valve installed backwards or stuck closed.
- Inlet screen on pump clogged.
- Hole in delivery piping below bore top.
- Motor failure.
- Broken pump shaft or coupling.
3. Low water delivered - Pump rotating backwards (3 phase only).
- Water level too low in bore.
- Discharge piping clogged, corroded or ruptured.
- Pump installed too low in bore and covered in sand or
other solids.
- Inlet screen partially clogged.
- Worn pump.
- Check valve stuck partially closed.
- Motor related problem.
4. Pump starts and stops too often - Water logged pressure tank.
- Pressure switch differential adjustment incorrect.
- Pressure tank too small.
- Other control problems (eg. probes too close).
5. Fuses blow but overload does not trip - Fuses too small.
- Fuse receptacles dirty or corroded.
- Loose connection in fuse box.
- Defective incoming power leads.
- Ground wire connected to wrong terminal.
- Motor failure.
6. Electric shock from water pipe or electrical components - Incorrectly wired incoming power leads.
- Ground wire connected to motor control equipment.
- Defective motor starter or control box.
- Incorrectly grounded motor.
7. Pressure gauge fluctuates with flow surges - Water level too low in bore.
8. Pump and/or motor corrosion due to electrolysis - Pump earthing to ground through poor splice
connection or cable chaffing.
- Unsatisfactory pH levels.
- Active single wire earth return electrical distribution
system.