How to use the electronic shaking table (megger)?

Key points of using electronic vibration table:

1. Before measurement, the power supply of the equipment under test must be cut off, and the short circuit to the ground should be discharged. Never let the equipment be charged for measurement to ensure personal and equipment safety. For equipment that may induce high voltage electricity, this possibility must be ruled out before measurement.

2. The surface of the measured object should be clean to reduce the contact resistance and ensure the correctness of the measurement results.

3. Before measurement, the megohmmeter should be tested for open circuit and short circuit to check whether the megohmmeter is in good condition. That is, before the megger is connected to the measured object, shake the handle to make the generator reach the rated speed (120r/min), and observe whether the pointer is in the ∞ position of the scale.

Short the terminal "line (L) and ground (E)", slowly shake the handle and observe whether the pointer is at the "0" position of the scale. If the pointer can't point to the finger position, it means that the megohmmeter is faulty and should be repaired before use.

4. When using the megohmmeter, it should be placed in a stable and firm place, and away from the external high current conductor and external magnetic field.

5. The wiring must be correct. There are generally three terminals on the megohmmeter, in which L is connected to the conductor part insulated between the measured object and the earth, and E is connected to the shell or the earth of the measured object.

G connects the shielded or non-measured part of the measured object. When measuring insulation resistance, only "L" and "E" terminals are usually used. However, when measuring the insulation resistance of the cable to the ground or the leakage current of the tested equipment is serious, the "G" terminal should be used and connected to the shielding layer or shell. When the line is connected, turn the crank clockwise.

The speed of shaking should be from slow to fast. When the rotating speed reaches about 120 revolutions per minute (ZC-25 model), keep rotating at a constant speed, read after 1 minute, and read while shaking, without stopping to read.

6. When shaking, put the megohmmeter in a horizontal position, and no short circuit is allowed between the end buttons when the crank rotates. Shake the handle from slow to fast. If the pointer is found to point to zero, the measured insulation may have a short circuit. At this time, you can't continue to shake the handle to prevent the coil in the instrument from being damaged by heat.

7. Discharge the device under test after reading. The discharge method is to remove the grounding wire for measurement from the megger and connect it to the device under test (not megger discharge).

Extended data:

Precautions for use:

1. It is forbidden to measure insulation resistance near lightning or high voltage equipment. Only when the equipment is not charged and there is no induced electricity can it be measured.

2. During the shaking test, no one is allowed to work on the tested equipment.

3. Megger wires should not be intertwined, but should be separated.

4. It is forbidden to touch the megohmmeter by hand before the megohmmeter stops rotating or the device under test discharges. Don't touch the metal part of the wire when removing it.

5. At the end of the measurement, discharge the large capacitance equipment.

6. The insulation of the measuring cord led from the megger terminal should be good, and a proper distance should be kept between the two wires and between the wires and the ground, so as not to affect the measurement accuracy.

7. In order to prevent leakage resistance on the surface of the equipment under test, when using a megger, the middle layer of the equipment under test (such as internal insulation between cable cores) should be connected to the protection ring.

8. Check its accuracy regularly.

Baidu encyclopedia-megohmmeter