Key points for using the electronic 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 likely to induce high voltage, this possibility must be eliminated before measurements can be made.
2. The surface of the object to be measured should be clean to reduce contact resistance and ensure the accuracy of the 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 ofthe scale.
Short 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 finger position, it indicates that the megger is defective and needs to be repaired 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. When measuring insulation resistance, usually only the “L” and “E” terminals are used. However, when the measuremente of the insulation resistance of the cable to ground or the leakage current of the equipment under test is serious, the "G" end should be used and the "G" end should be connected to the layer or the armor shell. Once the lines are connected, you can turn the handle 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. should be taken by shaking without stopping. Go down and do a reading.
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. If the pointer is at zero, it means that the measured insulation may be short-circuited. At this time, the handle cannotbe continued to prevent the coil inside the meter from heating up. and damaged.
7. After reading, 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:
Precautions for use:
1. It is prohibited to measure insulation resistance during lightning or near high voltage equipment. It can only be measured. when equipment is not charged Measured without 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 the equipment under test is dischargedrgé.It is strictly forbidden to touch it with your hands. When removing the wires, do not touch the metal parts of the cables.
5. Large capacity equipment must be unloaded at the end of the measurement.
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 resistance leakage on the surface of the equipment under test, the intermediate layer of the equipment under test (such as the internal insulation between the cores of the cable shell) should be connected to the protection cable. sound when using a megger.
8. Check its accuracy regularly.
Baidu-Megger Encyclopedia
How to use a Megohmmeter
The function of an electrician's Megohmmeter is to test the resistance of lines or equipments. value, or the resistance value of the line to ground, or the resistance value of the equipment to ground. The method of using the megger is to short the megger lead and gently shake it for half a turn. should return to zero, then the megger is open circuit and the etalon is open circuit, your 120 rpm speedometer pointer should point to infinity
1 . Before measuring, keep the megger horizontal. position, hold the meter body with your left hand and shake the megger with your right handle, the rotation speed is about 120 rpm and the pointer should point to infinity (∞), otherwise it means the megger is defective. ;
2. Before measurement, the power supply to the electrical device and circuit under test should be turned off and the relevant components should be inspected. megohmmeter and the accuracy of the measurement results. ;
3. The cWiring must be correct when measuring. The megger has three terminals (L, E, G). When measuring the resistance of the loop to ground, the L end is connected to the exposed conductor of the loop and the E end is connected to the ground wire or metal shell when measuring the resistance d 'loop isolation, the first and; the last ends of the loop are connected to L and E respectively; cable insulation is measured when measuring resistance, in order to prevent leakage current on the cable surface from affecting the measurement accuracy, the cable shielding layer should be connected to the terminal G;
4. The test lead exiting the megger terminal must be well insulated between the leads and between the leads and ground to avoid affecting the measurement. precision;
5. When shaking the megger, do not touch the megger terminals and the circuit under test with your hands to avoid electric shock.triques;
6. megger, do not short-circuit the terminals to avoid damage