How To Check Motor Winding With Multimeter

Checking motor windings with a multimeter is an essential skill for anyone dealing with electrical machinery or appliances. Whether you’re a professional technician or a DIY enthusiast, understanding how to use a multimeter to test motor windings can help you diagnose problems and ensure the efficient operation of motors in various applications.

Motors are the workhorses behind many devices, from HVAC systems to power tools, and identifying issues within their windings can prevent costly replacements and keep equipment running smoothly. In this guide, we will take you through the process of using a multimeter to check motor windings, giving you the knowledge and confidence to troubleshoot electrical motor problems effectively.

When a motor is turned on, voltage may be produced that could result in serious injury. The winding test’s main purpose is to check the wires for breaks or shorts when no power is being delivered to the windings. You can identify potential reasons for your electric motors to fail using this testing technique. It is important to understand how to use a multimeter to examine a motor’s winding.

What is an electric motor and how does it work?

An electric motor’s function is based on the idea that a wire carrying an electric current experiences force when it passes through a magnetic field. The wire moves as a result of this force because of its natural orientation. Here, a wire is attached to some sort of armature, causing a high-speed circular motion.

Diagnose the issue

The driving load is misplaced, trapped, or bound. If the motor has developed a flaw, it could be a burned wire or connection, a winding breakdown with insulation corrosion, or a failed bearing. If the shaft spins easily, switch the multimeter to the ohms function.

In a three-phase motor, all three windings should measure low, but not zero, ohms. If the motor is smaller and not open, this measurement will be higher.

How To Check Motor Winding With Multimeter

• You must first and foremost have a multimeter to test the windings.
• First, test the wires and terminals on your motor by connecting the multimeter to ohms. For any “short to ground” in the circuit, as well as any open or shorts, you should inspect the windings.
• Set your multimeter to ohms and unplug your motor from the power source to check for a short to the ground.
• Then check each wire for a seemingly limitless number of readings. If you get a reading of 0, you might have a cable problem.
• Test each cable independently to see whether it has a problem, and make sure that very few of the leads are making contact.
• If you test each one separately, you can identify the offending cable. You have a motor issue and need to hire a professional repair agency if every cable on each hand produces an infinite reading.
• Check the various indicators to see whether the windings have any open or short circuits. There will be different markings on different motors.
• The user manual for your motor should have the configuration information. In general, you want to measure between 3 and 2 ohms. If you get a reading of 0, you should retake the exam to check if the outcome is the same.
• Phase deficiency is indicated by a value of 0. A deficit happens when wires are broken by being shorted to the ground.
• Phase deficiency is indicated by a value of 0. A short circuit happens when wires are broken by being shorted to the ground.
• Your winding is certainly open if your reading is much greater than 2. A wire has only snapped when there is an open winding.

The most common faults in electric motors and how to troubleshoot them

Short circuit

The most frequent issue, a short circuit, may be caused by the accumulation of grease or dirt on the motor’s surface. This problem could be resolved with a quick cleaning using a dry cotton cloth. If not, thoroughly clean it with sandpaper before retesting it for winding continuity.

Open Circuit

This is another issue that is frequently encountered. Most of the time, it happens due to worn-out motor wires that break and disconnect. This can be fixed by soldering them back together or, in the worst circumstances, rewinding.

Intermittent shorted winding

Intermittently shorted winding happens when a wire breaks as a result of too much pressure or heat. You will need to carefully rewire it to prevent future harm.

Noisy operation

If a motor is running at a high speed and making an odd noise, it’s likely that one of its fan blades needs to be repaired or replaced.

High temperature

If it isn’t ventilated properly, all motors, regardless of their working voltage, will operate at high temperatures. The only option would be to improve its ventilation or swap it out for a suitable, high-quality fan.

 Overload

 This issue only arises when a motor is forced to run continuously at or over its rated capacity. As a result, the motor may sustain substantial damage and must be repaired before it can resume operation.

Conclusion

For the motor to run properly, the windings should have M measurements to ground, or the motor enclosure. Up until a winding is grounded out, the insulation on the windings has decreased, or the armature is in contact with the stator.

Check the motor winding resistance, or ohms value, for the phase-to-phase terminal using a multimeter or ohmmeter. The ohm reading for each winding must be the same.

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