How to quickly judge whether the insulation of a low-voltage motor is good?

Low voltage (below 500V) motor insulation is usually checked with a 500V insulation vibrator. What if you don't have an insulation tester and need to quickly assess motor insulation? Teach you a simple and effective judgment method, you can use the signal light to make a rough judgment. How to quickly judge whether the insulation of a low-voltage motor is good?

Connect the 220V signal light as shown in the figure below, turn on the power, and then make the following judgments:

1. The light bulb does not light up, indicating that the engine insulation is not bad and can be started;

2. The filament of the bulb is red, indicating leakage, and the motor insulation is slightly damaged. If production cannot be stopped, and if the protection device is sensitive and reliable, the motor can be temporarily used;

3. The light bulb is normal or very bright, indicating that the motor insulation is seriously damaged and cannot be used. Otherwise, it may cause a fall due to a short circuit.

Again, the dotted line indicates that the cable insulation can be checked.