How to use a multimeter to judge whether the motor with star-delta connection is burned out
The judgment is as follows:
1: Disassemble all connecting lines;
2: Looking from left to right, the order is: 123 (referring to the upper row); 456 (referring to the lower row);
3: 1-5 is the same phase, 2-6 is the same phase, 3-4 is the same phase;
4: Measure the resistance between phases with a shaker (megohmmeter: 1000 ohms);
5: The resistance of the three phases to the ground (that is, the shell);
6: Three phases are compared, and one phase is different (resistance value) from the other two phases, then it is determined that this phase is burnt;
Charging method:
Connect one phase line (i.e. live line) to the three phases respectively, measure the motor shell with an electric pen, if there is electricity in the shell of the charged phase, the phase will be burned; pay attention to safety;
How to check whether the star-delta step-down starting motor is burnt out,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, etc., use a multimeter
First, detect the six lead wires of the motor, that is, the head and tail of each phase (assuming 1 and 4, 2 and 5, 3 and 6 of the wire number),
Then, adjust the gear to the high-resistance gear, and the resistance value between the detection line numbers 1, 2, and 3 should be infinite, and the resistance value between them should not be lower than 0.5 megohm (shaking meter). If the resistance value is zero, Then there is a phase-to-phase short circuit in this item; the resistance between the 1, 2, 3 wires and the motor casing should also be infinite, and the inter-resistance value should not be lower than 0.5 megohm (shaking meter). If the resistance value is zero, then the There is a short circuit to ground.
Finally, using a multimeter to detect requires rich experience, and it is easier to judge the quality of the motor stator winding according to the detected resistance value.
How to use a multimeter to judge whether the motor is burned
The first measurement is whether the winding is on or off. If you don’t know the resistivity of the motor, directly set it on the resistance file ×10 or ×100. If it is not connected, it will be burned. If one end of the contact wire touches the casing, the pointer does not move, and the movement is intact, and the range is too large, which is not good. Third, if the motor is three-phase, you can measure whether the resistance of the three-phase winding is balanced.
How to use a multimeter to judge the quality of delta and star motors
For common asynchronous motors, there is actually no difference between delta and star motors, only the windings are connected according to the needs. A multimeter can only measure the difference in resistance of the three windings. Normally, the difference should be less than 5%. The shell resistance should be More than 3 megabytes, and the mechanical part cannot be checked, such as damage to the sweeping bearing, etc.
In fact, due to the range and accuracy of the multimeter, it can only be roughly judged
For example, a high-power motor has a very small coil resistance, which can only be measured with a bridge, while the insulation resistance can only be measured with a megohmmeter.
Not long ago, I encountered a piece of equipment. When the motor was turned on, the leakage protector was used to act. The insulation was tested with a multimeter. Finally, the insulation resistance was measured at 0.5M with a 500v shaker.
