How to Test Brushless Motor with Multimeter

How to Test Brushless Motor with Multimeter? Essential Tips

Have you noticed any problems with your brushless motor recently? Sometimes it doesn’t rotate when you connect it to the main circuit. Then if you want to fix this without removing the mounting, the first step is to test the motor.

This is simply a quick overview of how to inspect the brushless motor. You must read the specifics to understand the entire motor checking procedure.

We hope this article will give you the full information on how to test brushless motor with multimeter; keep reading!

What are brushless motor applications, and how do they work?

What are brushless motor applications, and how do they work

As brushless motors come in a variety of configurations, it is always a good idea to specify whether the motor is AC or DC.

An AC brushless motor could be an induction motor, synchronous motor, or permanent magnet synchronous motor. The main field winding on the rotor is connected to a rotating exciter on the shaft in traditional AC brushless synchronous motors.

On the DC field, it specifically applies to the pilot exciter changing the field voltage. On the shaft, the signal is amplified and converted into three phases. Additionally, the current is then passed through a rotating power rectifier, which converts it to DC and applies it to the mains.

What exactly does a brushless motor do?

A brushless motor operates by spinning the motor with electromagnets rather than brushes. The magnets are attached to the bell of the motor and push and pull the motor as needed. Power can also be generated by electromagnets. Power is generated when a motor is spun by hand.

3 Easy Steps: How to Test Brushless Motor with Multimeter

Test Brushless Motor with Multimeter

It is important to test and monitor the performance of a brushless motor on a regular basis. Check your brushless motor with a multimeter and carefully follow the instructions.

Let us now go through the steps-

Step 1: Determine the Resistance Value

First, you have to disconnect all power and amplifier connections from the drive. Then maintain the motor’s cable connection strictly.

Then switch your multimeter to the Ohms test mode. Connect the two testing probes to the corresponding jacks. Connect the black to “Com” and the red to “Ohms.” After that, set the multimeter’s needle to zero.

Take a reading on the three wires using the probes. Mark wires A, B, and C as needed. The phases of testing should be completed in the following order: AB, BC, and CA. Keep the motor’s cable connected to the drive.

The infinite reading indicates that there is no problem with the motor. When the motor reads 0 or any continuity, it means that it isn’t working properly.

Keep in mind that you should keep your multimeter’s leads separated at all times. They should also not come into contact with any other cables. Otherwise, they will not function properly.

Step 2: Determine Open and Shorted Winding Issues

Your brushless motor’s windings can be open or shorted. An open winding indicates that the motor winding has been damaged or separated. A shortened winding indicates insulation failure.

These issues can be diagnosed using a multimeter.

Check the connections between wires A and B, B and C, and C and A first. On average, the resistance of these wires should be between.3 and.8 ohms.

If the reading is zero, there is a short between the phases. An open winding is indicated by a reading of 2000 ohms or infinite.

Step 3: Inspect the Insulation System

In this step, a Mega ohm reader is taken to determine whether or not the motor is grounded. It can also tell if the brushless motor’s insulating system is up to snuff.

Just simply switch the multimeter’s red probe to the Megaohm jack.

You must provide 1000 rpm of incoming power to your motor. To accomplish this, connect your motor to a high-quality larger brushless motor.

After powering up the motor, check all three wires in the same manner as before. The reading will range between 600 and 2000 Megohms. The shorts must be less than 20 Megohms in length.

Here’s a rule of thumb: if the reading is less than 600 Megaohms, it could indicate cable damage.

Method for quickly assessing motor performance

Method for quickly assessing motor performance

Firstly, measure the DC resistance of the motors with the multimeter. Here comes the three-phase winding. The three measurement results are more approachable. If the difference is less than 2%, the winding resistance is qualified. If the difference exceeds 10%, the phase with the lower resistance is likely to have a turn-to-turn short circuit.

A 500V insulation megger can be used to test the insulation resistance between phases as well as the earthing (shelling) insulation resistance of a three-phase coil. If the value shows greater than 0.5 of the resistance, at this point, the motor can be considered to be in good working order. If the value is between 0.1 and 0.5, the motor has been moisturized and is ready to use after drying.

How to test your brushless motors


  • What advantages do brushless motors have?

Brushless motors are extremely efficient and require little maintenance. They have more torque and are more efficient than brushed motors.=

  • How long does a brushless motor last in operation?

A brushless motor can run for 10,000 hours without stopping. There’s no need to worry about anything wearing out because they don’t use brushes.

  • What are the special uses of brushless motors?

Brushless motors are used in industries, automobiles, and even airplanes. Brushless motors are the best choice when high performance and low maintenance are required.

Final thoughts

to Test Brushless Motor with Multimeter

I believe you won’t have any difficulties now while testing a brushless motor with a multimeter. You can now inspect the motor on your own as you have already learned how to test brushless motor with multimeter.

By following the same method, you can check all AC and DC motors, and the difference would be very little for both of them. After going through one testing, you would be known how to test another testing through a multimeter.

Don’t forget to tell us about your experience. Take care and have a wonderful day!