Why can't you use the multimeter to test the insulation?
In fact, the ohmmeter uses Ohm's theorem to measure the resistance. When the resistance is too large, the current flowing through the measured resistor is very small, which is easily affected by the interference and the environmental distribution parameters, and the measurement is inaccurate
The meter is limited in size, and the universal multimeter can only measure the resistance of 20M or 200M or 2000M, which cannot be measured at large
The resistance of the material has a certain relationship with the applied voltage, therefore, measure the insulation resistance, even using a shake table or megohmmeters, sometimes shaking table or clear the megameter voltage level. For example: 500V, 1000V, 2500V and so on.
