About the detection of heater

When testing a heater, it is usually believed that the result can be detected by simply connecting the megohmmeter head to the heater terminal and the other head to the heater shell. In fact, this is not the case:

First, the megohmmeter should be kept in a horizontal position before measurement, the left hand should hold the meter body, and the right hand should shake the megohmmeter handle. The speed should be about 120r/min, and the pointer should point to infinity (∞), otherwise it means that the meter is faulty; after the fault is eliminated, the heater power supply should be cut off immediately to ensure personal safety and accurate measurement results;

Secondly, the wiring must be correct during measurement. The megohmmeter has 3 terminals (L, E, G). PI heating film adopts a planar heating method, and the surface power density can reach 7.8 W/cm2. Cabinet dehumidification heaters are widely used in refrigeration devices such as medium and small food warehouses, household refrigerators, and water and road refrigeration transportation.
When measuring the resistance of the circuit to ground, the L end is connected to the exposed conductor of the circuit, and the E end is connected to the ground wire or metal casing;
When measuring the insulation resistance of the circuit, the head and tail ends of the circuit are connected to L and E respectively;
When measuring the insulation resistance of the cable, in order to prevent the leakage current on the cable surface from affecting the measurement accuracy, the shielding layer of the cable should be connected to the G end;
Therefore, remember not to connect the wires at will when detecting the leakage of the heater;
Finally, when measuring, do not touch the terminals of the megger and the circuit being measured with your hands to prevent electric shock; after the megger, the terminals cannot be short-circuited to avoid damage, and the time should not be too long;
After reading the above introduction, do you think that the megger detection is not that simple? Indeed, there is no need to worry. As long as you pay attention to the above steps, safe and accurate detection is not a problem. The discharge performance and charging acceptance of the lithium battery of the lithium battery heater are greatly reduced by the influence of low temperature. For example, if the power battery pack is arranged under the floor of the car, its bottom is inevitably exposed to the outside world even if it is completely sealed by the bottom plate of the car body. In addition, users are reminded that products such as heaters and silicone rubber heating sheets must be regularly tested for leakage to avoid safety accidents that would not be worth the cost.