How to Solve the Motor Overload Alarm? A Complete Troubleshooting Guide

HDBMOTOR explains the common causes behind a motor overload alarm and provides effective troubleshooting steps to help prevent motor failures, downtime, and production losses. A motor overload alarm indicates that the motor current has exceeded its rated value or that the internal temperature has risen abnormally, usually caused by excessive load, power issues, mechanical faults, or parameter errors.

1. Main Causes of Motor Overload Alarms

1) Excessive Load

When the mechanical load exceeds the motor’s rated torque, the motor is forced to draw a higher current, leading to overload alarms. Typical scenarios include:

Conveyor belt jams
Bearing seizure increasing resistance
Oversized load inertia (e.g., large fans starting)
Long-term operation above rated load

High inertia loads may also cause instantaneous overload during acceleration.

2) Power Supply Abnormalities

Unstable power supply is another major cause of overload. Common issues include:

Low voltage, forcing the motor to draw more current
Voltage fluctuations, affecting output torque
Phase imbalance, increasing losses and heat generation

Motors operating under unstable voltage conditions will easily trigger overload protection.

3) Mechanical Failures

Mechanical component failures increase internal resistance and lead to overload alarms. These include:

Damaged bearings
Stator–rotor friction
Misaligned coupling
Blocked cooling ducts or failed cooling fans

Inadequate cooling significantly accelerates the temperature rise, leading to overload alarms.

4) Improper Configuration or Incorrect Parameters

Improper system setup can also cause overload:

Motor power too small for actual load
Incorrect inverter/driver settings
Acceleration time too short
Current limits set too high or too low

A mismatched motor will run near full load continuously, eventually triggering an overload alarm.

2. Solutions for Motor Overload Alarms

1) Reduce or Correct the Mechanical Load

Remove mechanical obstructions
Replace damaged bearings
Realign transmission components
Add a soft starter or inverter (VFD) to reduce startup impact for high-inertia loads

These steps help restore correct torque demand and stabilize motor operation.

2) Ensure Stable Power Supply

Measure input voltage
Use voltage stabilizers or compensation devices
Maintain voltage within ±5% of the rated value
Eliminate phase imbalance

Stable voltage ensures the motor does not draw excessive current.

3) Repair Mechanical Failures

Fix damaged bearings, couplings, or shafts
Remove friction between stator and rotor
Clean cooling ducts and check the fan
Improve ventilation

Good mechanical condition and heat dissipation reduce the risk of overload.

4) Optimize Equipment Selection and Parameter Settings

Select a motor with appropriate rated power and torque
Adjust drive parameters to match the load
Set overload protection based on rated current
Enable inverse time-delay protection to avoid false triggers

Proper configuration significantly enhances motor reliability.

3. Emergency Actions When Overload Alarms Occur

If the motor triggers overload frequently, IMMEDIATELY shut down the equipment to prevent winding burnout. Then:

Measure operating current and compare with rated value
Inspect circuit breakers and thermal relays for incorrect settings
Check for winding short circuits (e.g., burnt smell or local overheating)
Examine the control system for malfunction

Overload should never be ignored, as prolonged stress shortens insulation life and significantly reduces the motor’s lifespan. When in doubt, contact a motor specialist or HDBMOTOR for professional diagnosis.

How to Solve Motor Overload Alarm: Complete Guide by HDBMOTOR