How to measure the quality of a three-phase motor

In fact, there are many ways to check the quality of a motor. Below, I will take a three-phase motor as an example and systematically explain the inspection methods for three-phase motors for reference.

Before understanding the measurement methods of three-phase motors, let me briefly explain what three-phase motors are. "Three phase" in three-phase motor means that after the motor is connected to the three-phase current, the three-phase stator winding of the motor (each with a difference of 120 degrees of electrical angle) will produce a rotating magnetic field. This rotating magnetic field will cut the rotor winding, thus generating induced current in the rotor winding (the rotor winding is a closed path). The current carrying rotor conductor will generate electromagnetic force under the action of the stator rotating magnetic field, thus forming electromagnetic torque on the motor shaft, Drive the motor to rotate in the same direction as the rotating magnetic field.

Taking a three-phase asynchronous motor as an example, how to check if the coil of the motor is damaged and what instrument should be used?

1. A single arm bridge can accurately measure the coil resistance and determine whether the resistance of each phase of the coil is close.

2. A multimeter can be used to check and measure the continuity of the motor coil.

3. When using a megohmmeter to measure the insulation resistance between motor phases and between phases and ground, it should not be less than 0.5 megohm. This means that when we use a 500V megohmmeter to measure the insulation resistance, a resistance greater than 0.5M indicates that the motor is normal, and a resistance less than 0.5M indicates that the motor has been damaged. However, this is only an appearance judgment. For inter turn short circuit and inter phase breakdown, it can only be disassembled and inspected.

The main causes of motor failure are in two major areas, namely mechanical and electrical aspects.

1. Mechanical aspects:

① Is the end cover "running out of the outer sleeve" and the bearing "running out of the inner sleeve".

② Is the bearing lacking oil or damaged.

2. Electrical aspects

① Measure whether the three-phase DC resistance is qualified using a double arm bridge.

② Is the insulation resistance qualified.

③ Whether the rotor is broken or not, and the DC resistance of the motor is an important basis for judging the motor.

How to conduct quality inspection for AC single-phase motors?

1. The insulation resistance of the motor winding and casing measured with a 500V megohmmeter should not be less than 0.5 megohms; Measure each lead of the winding with a multimeter and do not break the wire. All the above items have met the requirements and the motor has performed well.

2. Use a pointer multimeter or a digital meter with a capacitance range to detect the quality of the capacitor, which can be directly measured.

3. Set the multimeter to the resistance range of 1K or 10K, measure the two leads of the capacitor, wait for the needle to quickly deflect to the right, and then slowly return to the left capacitor for correction; Always leaning to the right indicates that the container has been punctured; The pointer does not move, the container is internally disconnected or has no capacity.

How to judge the quality of a DC motor?

Firstly, check if there are any broken wires and if the resistance value is normal. If there is a brush DC motor, the rotor can be rotated, and whether the output DC current is normal can be measured with a multimeter. If it is a brushless DC motor with three-phase lead out, the rotor can be rotated, and the output AC voltage is normal, use a multimeter to measure. The magnitude of the voltage is directly proportional to the output speed.

The above is a simple method for judging the quality of three-phase motors

Zhejiang Jinsu Motor Co., Ltd. is an enterprise that manufactures various types of DC, AC, and three-phase asynchronous motors. The company covers a total area of over 30 acres and currently employs more than 150 employees; Having a modern garden style factory building and introducing excellent and efficient production and testing equipment from both domestic and international sources, we aim to create a sustainable manufacturing enterprise that provides customers with excellent products and services. As a modern enterprise that integrates scientific research, production, sales, and service, we are committed to building a sustainable business.