How to use the megger:
1. Before measurement, the power supply to the equipment under test must be turned off and the device must be short-circuited and discharged to ground. Never allow the equipment to be powered for measurement to ensure the safety of people and equipment. For equipment that may induce high voltage electricity, this possibility must be eliminated before measurements can be made.
2. The surface of the object to be measured must be clean. Reduce contact resistance and ensure the accuracy of measurement results.
3. Before measurement, the megger should be subjected to open circuit and short circuit test to check whether the megger is in good condition. That is, before connecting the megger to the object to be measured, shake the handle so that the generator reaches the rated speed (120 rpm) and observe whether the pointer points to the “∞” position of the scale.Short circuit the “line (L) and ground (E)” terminal, slowly shake the handle and observe whether the pointer points to the “0” position of the scale.
If the pointer cannot point to the desired position, this indicates that the megger is defective. It must be inspected before use.
4. When using the megger, it should be placed in a stable and solid place away from large external current conductors and external magnetic fields.
5. The wiring must be correct. There are generally three terminals on the megger, among which L is connected to the insulated conductive part between the tested object and the ground, and E is connected to the shell of the tested object or the ground. G is connected to the shield of the tested object or the part that does not need to be measured. Use terminals “L” and “E” to measure insulation resistance.
However, when measuring the insulation resistance of the cable at the terre or the leakage current of the device under test is serious, the "G" end should be used and the "G" end should be connected to the shielding layer or shell. Once the lines are connected, you can turn the toggle clockwise. The stirring speed should be slow to fast. When the rotation speed reaches approximately 120 revolutions per minute (ZC-25 model), continue rotating at a constant speed and take a reading after 1 minute. Reading must be taken while shaking and cannot be performed. to be arrested.
6. Place the megger in a horizontal position during shake measurement and do not allow short circuit between the terminal knobs when the handle is turned. The handle should be shaken slowly and gradually faster. If the pointer points to zero, it means that the measured insulation may have a short circuit. At this time, the handle cannot continue to shake for emfish the reel from lying in the reel. meter from being heated and damaged.
7. Once the reading is complete, discharge the device under test. The discharge method involves removing the ground wire used when measuring the megger and shorting it to the device under test (no discharging the megger).
Detailed information:
Notes:
1. It is prohibited to measure insulation resistance during lightning or near high voltage equipment. It can only be measured when the equipment is not charged and there is no induced electricity.
2. During the shake test, no one may work on the equipment under test.
3. The megger wires cannot be twisted together, but must be separated.
4. Before the megger stops rotating or before the device under test is discharged. It is strictly forbidden to touch it withc the hands. When removing the wires, do not touch the metal parts of the cables.
5. At the end of the measurement, large capacity equipment must be unloaded.
6. The flexible measuring wire coming from the megger terminal should be well insulated and a proper distance should be maintained between the two wires and between the wire and the ground to avoid affecting the measurement accuracy.
7. In order to avoid leakage resistance on the surface of the equipment under test, when using a megger. The middle layer of the equipment under test (such as the internal insulation between the cores of the cable shell) should be connected to the protective ring.
8. Check its accuracy regularly.
Baidu-Megger Encyclopedia