How to Commission a Deep Well Submersible Pump After Installation

Commissioning checks that a deep well submersible pump is correctly installed and can operate safely at its required flow and head.

A suitable pump can still fail during its first start because of an unprepared motor, damaged cable, incorrect rotation, low voltage, a closed valve or insufficient water. Follow the instructions supplied with the exact pump, motor, control panel and variable-frequency drive (VFD).

1. Confirm the Equipment and Well Data

Before applying power, record:

• Pump and motor models
• Rated power, voltage, frequency and current
• Pump installation depth
• Cable size and length
• Rising-main size and material
• Static and dynamic water levels
• Required flow and total dynamic head
• Distance from the motor to the well bottom

The complete pump and motor must remain submerged during operation and safely above sediment. Pump installation depth is not the same as pump head. Required head depends mainly on the pumping water level, discharge elevation, pipeline losses and required outlet pressure.

2. Prepare the Motor

Some rewindable water-filled motors must be filled with clean water before operation. The SLAPK QJ instructions show filling the motor cavity and allowing trapped air to escape.

For a field-filled motor:

1. Confirm the required filling liquid.
2. Remove the specified filling or vent plug.
3. Fill the motor completely.
4. Release trapped air.
5. Reinstall the plug and check for leakage.

Not every motor uses this procedure. Factory-filled, oil-filled and sealed motors should not be opened unless their instructions specifically require it.

3. Inspect the Installation

Check that:

• The wellhead and rising main are properly supported.
• Flanges, bolts and threaded joints are secure.
• The power cable does not carry the pump weight.
• Cable clamps do not damage the insulation.
• Check valves point in the correct flow direction.
• The discharge pipeline is restrained.
• Gauges and flowmeters have suitable ranges.
• The discharge route can safely receive water.

If the well may initially produce sand or turbid water, direct the first discharge to a safe drainage or settling area.

4. Complete the Electrical Checks

Qualified personnel should test the motor and cable before startup. Checks may include:

• Conductor and protective-earth continuity
• Motor winding resistance
• Phase resistance balance
• Insulation resistance
• Underwater splice condition
• Terminal tightness

Testing before and after lowering the pump helps identify installation damage. A major reduction in insulation resistance can indicate a damaged cable, crushed insulation, faulty splice or moisture entry.

Use the test voltage specified by the motor manufacturer. Disconnect a VFD and sensitive electronics when required before insulation testing.

Measure all phase-to-phase supply voltages. Check voltage again during startup because a weak supply, small cable or overloaded generator may produce acceptable voltage without load but excessive voltage drop when the motor starts.

5. Set the Protection System

Configure the control panel from the confirmed motor data. Protection may include:

• Overload and short circuit
• Phase loss or imbalance
• Under-voltage and over-voltage
• Ground fault
• Dry running
• Low water level
• Excessive starts

Do not increase the overload setting simply to prevent a trip. First check for low voltage, incorrect rotation, excessive flow, sand or mechanical resistance.

For a VFD, enter the exact motor voltage, current, frequency and speed. Confirm the permitted minimum frequency and acceleration and deceleration times.

6. Make a Controlled First Start

Clear personnel from the wellhead and discharge area. Set the discharge valve to the starting position specified by the pump manufacturer. Many centrifugal pumps start with the flow-control valve partly closed and then open it gradually.

Do not operate against a completely closed valve for an extended period.

Start the pump and immediately observe:

• Water arrival
• Discharge pressure
• Motor current
• Supply voltage
• Noise and vibration
• Leaks or pipeline movement
• Control-panel alarms

Stop the pump if no water appears within the expected time, the current is abnormal, voltage falls excessively or severe vibration occurs. Do not repeatedly restart a pump that fails this check.

7. Confirm Rotation and Operating Performance

A three-phase pump may rotate in the wrong direction if the phase sequence is incorrect. Reverse rotation can cause low flow, low pressure and abnormal current. A reverse-running pump may still deliver some water, so water at the outlet does not prove correct rotation.

Follow the manufacturer's method for comparing pressure, flow and current. If correction is required, isolate the power and have qualified personnel interchange two phases.

After confirming rotation, open the valve gradually. At the intended operating point, record:

• Flow rate
• Discharge pressure
• Current on every phase
• Running voltage
• Dynamic water level
• Pump speed or VFD frequency

Compare the result with the approved pump curve. If performance is low, check rotation, water level, valve position, pipe friction, check-valve loss, rising-main leakage and instrument accuracy.

High current may indicate excessive flow, low voltage, sand or mechanical friction. Low current may indicate dry running, low flow, incorrect rotation, a blocked intake or a broken shaft.

8. Monitor Water Level and Water Quality

Measure the dynamic water level while pumping at the required flow. If the level continues falling toward the pump, reduce flow or stop the test. Dry-run protection should stop the unit before the intake loses the required submergence.

Also check for sand, turbidity, air, gas and unstable flow. Persistent sand may indicate incomplete well development, excessive pumping rate or an unsuitable pump position. Continuous abrasive operation can wear impellers, bearings and check valves.

Confirm that water flows past the motor as required for cooling. Large-diameter wells, tanks and top-feeding wells may need a cooling sleeve.

9. Check Shutdown and Automatic Controls

Stop the pump normally and observe pressure decay, check-valve noise, reverse flow, pipe movement and water hammer. A loud impact may indicate check-valve slam or another transient problem.

After manual operation is stable, test automatic functions such as:

• Pressure or tank-level control
• Dry-run shutdown
• Recovery restart
• Phase-loss and overload protection
• Alarm output

Do not place the pump into unattended service until the main protection functions have been tested.

Commissioning Record

Keep a record of:

• Pump and motor identification
• Installation depth
• Static and dynamic water levels
• Flow and pressure
• Voltage and phase currents
• Insulation-test results
• Protection and VFD settings
• Water and sand condition
• Shutdown observations
• Corrective actions

These measurements provide a baseline for future maintenance.

Common Mistakes

Avoid starting an unprepared motor, assuming rotation is correct because water appears, checking only one phase current, ignoring dynamic water level, opening the valve too quickly, pumping excessive sand or repeatedly resetting a protection trip without finding its cause.

Frequently Asked Questions

Does every submersible motor need to be filled?

No. Fill only a motor designed for field filling. Do not open a factory-filled or sealed motor without specific instructions.

Why is the motor current too high?

Possible causes include excessive flow, low or unbalanced voltage, sand, mechanical resistance or operation outside the pump curve.

Why is the flow lower than expected?

Check rotation, pump speed, dynamic water level, total head, valve position, pipe loss, voltage and rising-main leakage.

How long should commissioning continue?

Operate long enough for the pump, pipeline and well level to stabilize. Water reaching the outlet is only the beginning of the test.

Conclusion

Deep well pump commissioning should verify the motor preparation, cable condition, power supply, protection settings, rotation, current, flow, pressure, dynamic water level and shutdown behavior.

Do not place the pump into normal service until its electrical condition, hydraulic performance, well response and safety controls have been confirmed and recorded.

Request a Deep Well Pump Commissioning Review

Send SLAPK your required flow and head, pump and motor models, well depth, installation depth, water levels, voltage, frequency, cable length and starting method.

Our engineers can provide the QJ or SP pump curve, motor data and startup requirements needed for your project.

Contact SLAPK for deep well pump commissioning support