Common Failures in Electric Motors and Water Pumps: Prevention and Solutions

Introduction

Electric motors are essential in industrial and commercial applications, including pumping systems where water pumps rely on electric motors for operation. However, they are exposed to various electrical and mechanical failures that can compromise their performance and result in costly repairs. In this article, we will analyze the most common failures in electric motors, their effects, and how to prevent them.

1. Motor Overload

When a motor operates under a load greater than its rated capacity, it draws excessive current, leading to overheating and insulation deterioration in the windings.

This issue often arises when the motor is undersized, the mechanical load is obstructed, or the system lacks proper maintenance. If overload persists, the motor may suffer irreversible damage. In the case of water pumps, operating under overload can cause excessive heat, damage mechanical seals, and lead to leaks, reducing the equipment’s service life.

2. Phase Failure

A loss of one phase in a three-phase power supply creates an imbalance in the current, causing overheating of the windings and a drastic reduction in motor efficiency. This condition commonly occurs due to blown fuses, supply line issues, or faulty connections. If the motor continues running under these conditions, it can burn out quickly.

3. Voltage Imbalance

When the voltages of the three phases are not equal, the motor experiences unbalanced current, leading to excessive heating in the windings and reduced efficiency. A voltage imbalance of just 2% can increase motor temperature by 10%, significantly reducing its lifespan.

Voltage imbalance typically results from poor electrical distribution, uneven loads, or transformer and power network problems. Monitoring and correcting these discrepancies is essential to prevent premature failures.

4. Reverse Phase Sequence

If the phase sequence of the power supply is reversed, the motor will rotate in the opposite direction. In some systems, this can cause severe mechanical failures and compromise operational safety. This issue often arises after maintenance work or modifications to the electrical installation without proper verification.

5. Voltage Variations (Under or Overvoltage)

Operating a motor outside its nominal voltage range can result in excessive or insufficient current draw, affecting its performance. Low voltage forces the motor to consume more current to maintain its load, leading to overheating. Conversely, high voltage accelerates insulation degradation and shortens the motor’s lifespan.

These variations may be caused by fluctuations in the power grid, issues with generators or transformers, and faulty wiring. It is crucial to have protective devices that safeguard the motor from these changes.

6. Low Load and Dry Running Protection

In the case of water pumps, running without water can lead to overheating and severe damage, as they rely on the liquid for cooling and proper operation. To prevent this, protective devices monitor motor load, detecting when the pump is running dry without requiring electrodes or float switches. This ensures a more precise and reliable response to low suction levels, protecting both the motor and pump from costly damage.

7. Locked Rotor

A locked rotor occurs when the motor attempts to start but cannot rotate due to mechanical obstruction or an issue with the connected load. This condition results in excessive current draw and can severely damage the motor windings within seconds. In water pumps, a locked rotor can be caused by debris in the suction line, preventing impeller rotation and overloading the motor.

Having protection systems that detect this condition and shut down the motor before irreversible damage occurs is crucial.

8. Shaft Breakage

Shaft breakage can occur due to excessive mechanical stress, improper load alignment, or material fatigue from continuous vibrations. This failure results in total loss of motor operation and can damage other system components. In water pumps, shaft breakage may stem from misalignment with piping systems, hydraulic shocks, or excessive vibrations that generate extreme mechanical stress.

Continuous load monitoring and proper alignment of coupled equipment help prevent this failure.

Conclusion

Electrical and mechanical failures can compromise the efficiency, safety, and durability of electric motors. Implementing a reliable protection system helps detect anomalies early and prevent severe damage.

To ensure safe and efficient motor operation, continuous monitoring and protection against electrical and mechanical failures are essential.

Solution: Motor Monitor

To prevent these failures and protect electric motors, Nassar Electronics has developed the Motor Monitor, a protection relay that continuously monitors motor electrical conditions and reacts immediately upon detecting abnormalities.

The Motor Monitor helps prevent damage, reduce maintenance costs, and optimize motor performance. Learn more here: View Motor Monitor

For more details on its operation, watch the video here: Watch Video