QW Submersible Sewage Pump Current Rising Abnormally? Possible Causes Behind the Problem

 QW Submersible Sewage Pump Current Rising Abnormally? Possible Causes Behind the Problem

In wastewater treatment systems, municipal drainage projects, industrial wastewater transfer, and construction site dewatering applications, the QW submersible sewage pump is widely used due to its compact structure, reliable performance, and excellent solids-handling capability.

However, during long-term operation, some users encounter a common issue: the operating current gradually increases beyond the rated value. Although the pump may still be running normally, abnormal current is often an early warning sign that should not be ignored.

1. Impeller Blockage or Increased Hydraulic Resistance

One of the most common reasons for rising current is partial blockage inside the impeller or pump casing.

Fibers, plastic debris, sludge deposits, or solid particles can accumulate around the impeller, increasing rotational resistance and forcing the motor to draw more power.

Regular inspection and cleaning can effectively prevent this issue.

2. Excessive Flow Operation

Many users assume that a higher flow rate is always beneficial. In reality, when a pump operates beyond its design duty point, shaft load increases significantly.

As hydraulic load rises, motor current also increases, which may eventually lead to overheating or premature motor failure.

Selecting a pump according to actual system requirements is critical for long-term reliability.

3. Bearing Wear and Mechanical Friction

After extended service, bearings may wear out due to lubrication degradation, contamination, or normal mechanical fatigue.

Worn bearings increase friction between rotating components, causing the motor to consume more electrical energy.

Typical symptoms include:

Increased operating current

Higher vibration levels

Abnormal noise

Elevated bearing temperature

4. Voltage Instability

Electrical supply issues can also contribute to abnormal current readings.

Low voltage conditions force the motor to compensate by drawing higher current to maintain output torque. Long-term operation under unstable voltage can accelerate insulation aging and reduce motor life.

Routine electrical inspections are recommended, especially in industrial environments.

5. Medium Property Changes

Changes in wastewater characteristics are often overlooked.

If the liquid becomes denser, more viscous, or contains a higher concentration of solids than originally designed, pump load increases accordingly.

As a result, motor current may rise even though the pump itself remains mechanically sound.

Preventive Measures

To minimize current-related problems, operators should:

Clean the pump and impeller regularly

Monitor current and vibration trends

Check bearing condition periodically

Maintain stable power supply quality

Ensure operating conditions remain within design parameters

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Conclusion

An abnormal increase in operating current is rarely a random event. In most cases, it indicates hydraulic resistance, mechanical wear, electrical issues, or changing process conditions.

Early diagnosis and preventive maintenance can help avoid unexpected downtime, reduce energy consumption, and extend the service life of QW submersible sewage pumps.