Common Faults of Deep Well Pumps

Submersible deep well pumps commonly experience six major types of on-site frequent faults: motor failure, insufficient water output, no water delivery, tripping, abnormal noise & excessive vibration, water leakage & electric leakage, and overheating & motor burnout.

I. Complete Loss of Water Supply (Most Common Fault)

Reverse rotation (after new installation or rewiring)

The three-phase power phase sequence is connected incorrectly, causing the impeller to rotate backward with no water output.

Solution: Swap any two power wires to achieve forward rotation.

Excessively low water level with the pump exposed above the water surface

The dynamic water level drops below the pump inlet, resulting in dry running.

Solution: Wait for the water level to rise, or lower the pump. Dry operation is strictly prohibited.

Full blockage of the filter screen / water inlet

Sediment, aquatic weeds and plastic bags clog the bottom strainer.

Solution: Lift the pump to clear debris. Well cleaning is required if the well contains excessive silt.

Seized impeller or rusted bearings

Long-term idle storage or high sand content in well water causes the impeller to lock up with sediment.

Solution: Cut off power and manually turn the shaft. If it cannot rotate, disassemble to clean the impeller and replace bearings.

Riser pipe rupture, flange water leakage or pipe joint detachment

Water flows back midway, resulting in no water at the wellhead.

Solution: Inspect the riser pipe section by section, retighten connections or replace damaged piping.

Damaged bottom valve (check valve) stuck open

Water backflows after shutdown, leading to failure to pump water upon restart.

Solution: Replace the non-return valve at the bottom of the well pipe.

II. Low Water Output, Weak Pressure and Inadequate Flow Rate

Partial clogging of the inlet strainer leading to insufficient inflow

Semi-blockage causes inflow to fail to keep up with outflow.

Worn impeller with excessive clearance (a common issue for sandy well water)

Long-term pumping of sand wears the impeller wear ring, causing internal backflow and pressure loss.

Solution: Replace the impeller and wear-resistant wear ring.

Air leakage in pipelines or damaged flange gaskets

Air ingestion leads to cavitation and reduced water flow.

Low supply voltage

Low-voltage operation reduces rotational speed, lowering both flow rate and head noticeably during peak electricity consumption hours.

III. Power Tripping Upon Startup with Protector Activation

Earth leakage tripping (residual current circuit breaker trips)

Damaged and water-penetrated power cables, or failed motor sealing cause dampened windings and insulation breakdown.

Inspection: Test insulation resistance with a megohmmeter. Replace cables and rework the motor mechanical seal if insulation is too low.

Overload / overcurrent tripping (air switch / thermal protector trips)

① Seized impeller or locked bearings leading to excessive load; ② Phase loss or three-phase voltage imbalance; ③ Sharp current surge due to low voltage.

Internal short circuit

Burnt motor windings result in phase-to-phase short circuit, triggering immediate tripping on power-up accompanied by a burning odor.

IV. Abnormal Operating Noise, Severe Vibration and Shaking

Excessive clearance from bearing wear

A humming metallic friction sound occurs during operation, which will eventually cause rotor-stator rubbing.

Eccentric impeller rubbing against the pump casing

Hard gravel deforms the impeller, creating friction between rotating and stationary components.

Vertically misinstalled or bent riser pipes

Resonance and vibration occur along the entire well pipe with obvious shaking at the wellhead.

Poor pump fixation, suspended installation underground and lack of centralizers

Long deep-well pipelines swing violently; install rubber centralizer sleeves.

Cavitation noise (gurgling bubble sounds)

Air is sucked in due to low water level; lower the pump position in a timely manner.

V. Overheated Motor with Scalding Surface

Prolonged phase-loss or low-voltage operation causes temperature rise from overloaded current.

Insufficient submersion depth of the motor results in poor heat dissipation. Submersible pumps must be fully immersed in water.

Overloaded pumping where actual flow far exceeds the rated flow rate.

Bearing damage generates frictional heat, with temperature rising alongside abnormal noise.

VI. Water Seepage, Sand and Oil Ingress

Aging and damage of the mechanical shaft seal

Water seeps into the motor oil chamber and emulsifies the lubricating oil, which can easily burn out the windings. High sand content in well water accelerates seal wear; regular seal replacement is recommended.

Failed sealing at the cable outlet allows water to infiltrate the motor along the cable.

Excessive sand concentration in well water rapidly damages the mechanical seal, impeller and bearings during long-term pumping.

Solutions: Install pre-filtering equipment and conduct periodic well cleaning.

VII. Other Minor Faults

Difficult startup & slow rotation after power-on: Low voltage, faulty capacitor (single-phase deep well pumps), rusted bearings, or power phase loss.

Normal water pumping yet unstable fluctuating pressure: Dramatic water level fluctuation, air intake, trapped air inside pipelines, or stuck check valve.

Frequent automatic shutdown: Activation of the built-in thermal protector (overheating), faulty liquid level controller, or power cut caused by loose wiring connections.