How To Troubleshoot 3 Phase Electric Motor Problems

Figure 1 How To Troubleshoot 3 Phase Electric Motor Problems

Figure 1: How to troubleshoot 3 phase electric motor problems

The industrial sector is the backbone of many businesses and requires reliable power to operate. This is why properly functioning 3-phase electric motors are so important. Whether powering an HVAC system, running manufacturing line machinery, or heating water for a swimming pool, it can be costly and time-consuming when these machines need repairs.

3 phase electric motors are not like regular single-phase motors. They are more powerful and have a slightly different electrical configuration, which requires specialized troubleshooting techniques that need to be employed for proper diagnosis.

Do You Know?

According to the U.S. Department of Energy, almost 50% of all outages and motor failures occur due to improper maintenance. This guide will walk you through the most common 3-phase electric motor problems and how to diagnose them quickly and effectively.

How to troubleshoot 3 phase electric motor problems

Troubleshooting problems hurt the performance of a 3-phase electric motor, ultimately destroying your machine if not checked properly.


Many common problems can be quickly identified and solved. Let’s take a look at some of the most common 3-phase electric motor problems and how to troubleshoot them:

  • Unbalanced supply voltage

Figure 2 Checking The Voltage Balance

Figure 2: Checking the voltage balance 

An unbalanced supply voltage is a dreaded problem when troubleshooting three-phase electric motors. If you’ve been tasked with finding the solution, fear not, it’s quite simple. Simply ensure that each of the three phases has the same voltage magnitude and identical phase angle. 

This will help the motor run more efficiently, reducing wear and tear on the mechanical parts and, most importantly, your mental health. 

The challenge will be getting those power measurements sorted out accurately so you can make sure nothing has gone awry. Completing this task shouldn’t require too much effort or energy if you’re up to it.

  • Locked rotor

A locked rotor is one of the most common 3-phase motor problems caused by an imbalanced load. This can be caused by several things, such as:

  • The current flow through the winding is too high
  • Wrong connection to the windings
  • Defective bearings that are causing friction in the motor
  • High temperature due to overloads

The Solution: 

You need to identify the source of the load imbalance to overcome this issue. This could include inspecting and replacing faulty electrical components, checking and replacing bearings causing friction, or reducing the current flow through the windings.

 Once you’ve identified and solved the root cause of the issue, your 3-phase motor should be back up and running in no time.

  • Noisy operation

A noisy operation could mean loose parts, worn brushes or bearings, or even a faulty rotor causing the problem. To troubleshoot this issue, locate where the noise is coming from. Doing this will help you identify the faulty part, and then you can replace it. 

Workers often avoid this problem, saying it is minor, 

The Reality:

In reality, it causes the major failure of the motor. It is an initial sign that something bigger is coming. So try to inspect your 3-phase motor regularly, and if you find any noise, contact motor services.

  • Phase reversal cause of motor failure

This is another common 3-phase motor problem. If two of the three phases become reversed, it could cause severe vibration or overloading of the motor. To rectify this issue, you should check whether the power supply is connected properly and all connections to ensure they are secure. 

  • Underground voltage line damage

Sometimes, underground voltage lines can become damaged, leading to a 3-phase electric motor failure. To diagnose this issue, you should check the power supply line for any signs of damage that could prevent it from providing adequate power to your motor. 


You should inspect all connections and terminals attached to the motor for any loose or broken wires that could be causing the problem. 

Once you have identified and repaired damaged lines, your 3-phase motor should start working again. You can use a multimeter to test for any loose connections.

  • Overheating the motor

Figure 3 Why Does 3 Phase Electric Motor Overheat

Figure 3: Why does 3 phase electric motor overheat

This is often caused by excessive load or blocked cooling vents. To troubleshoot this issue, check the motor’s temperature to determine if it’s overheating. 

If so, 

You should reduce the load on the motor and also make sure that there are no obstructions preventing air from flowing through its cooling vents. Additionally, you should inspect all the electrical components and replace any faulty or worn out.

Contamination causes motor failure

Contamination could also cause a 3-phase motor failure. This could occur from oil, dust, or dirt entering the motor’s winding. Or if you are working in an environment with high humidity, it could cause the winding to corrode and lead to a motor failure. 

To troubleshoot this issue: 

Inspect all the electrical components for any signs of corrosion or contamination from oil, dust or dirt. Clean them thoroughly with a dry cloth and replace any that are damaged. Then, keep the motor clean and regularly maintained so you don’t experience this issue again.


In conclusion, there are many different causes of 3-phase motor failure. Regular inspection and maintenance of the motor are essential to prevent this issue. If you are unaware of the common causes of motor failure, your motor could be subjected to major repair costs that are much more expensive than proper maintenance. 

XINUUO MOTORS provides expert advice and tips on how to avoid motor failure and offers top-quality 3-phase motors designed to last. Contact us today for more information, and let us help you keep your 3-phase motor running smoothly.


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