Digital high-voltage megohmmeter repair and maintenance

1. Choose a megohmmeter that meets the voltage level. In general, 500V or 1000V meter should be used for equipment with rated voltage below 500V; 1000V~2500V meter should be used for equipment with rated voltage above 500V.

2. It can only be measured when the equipment is not charged and there is no induced electricity.

3. Before the measurement, perform an open circuit and short circuit test on the shaker to check whether the shaker is in good condition. Open the two connecting wires and shake the handle. The pointer should point to "∞", and then short-circuit the two connecting wires. The pointer should point to "0". Those who meet the above conditions are good, otherwise they cannot be used.

4. When measuring the insulation resistance, generally only the "L" and "E" terminals are used, but when measuring the insulation resistance of the cable to the ground or the leakage current of the device under test is serious, the "G" terminal should be used, and the " G" terminal is connected to the shielding layer or shell. In this way, the current flowing through the insulating surface no longer passes through the measuring coil of the ratiometer, but directly flows through the G terminal to form a loop. Therefore, the measured insulation resistance is only the volume resistance of the cable insulation.

5. After the line is connected, you can turn the handle clockwise. The shaking speed should be slow and fast. When the speed reaches about 120 revolutions per minute (ZC-25 type), keep rotating at a constant speed and shake Reading, can't stop reading.

6. It is strictly forbidden to touch it with your hands before the meter has not stopped rotating or before the device under test is discharged. At the end of the measurement, discharge the large-capacitance equipment. The discharge method is to remove the ground wire used during measurement from the shaker and short-circuit the device under test.

7. Generally, the small scale is 1M ohm, and the measurement resistance should be greater than 100K.

8. It is forbidden to measure the insulation resistance during lightning or near high-voltage equipment. During the shaking test, no one can work on the tested equipment. In addition, its accuracy should be checked regularly.