Illustration of how to use digital megger

Commonly used (insulation resistance meters) in operation are hand-operated megohmmeters and digital megohmmeters. The hand-operated megohmmeter consists of a dial, a pointer, a terminal block (e ground terminal block, l phase line terminal block), It consists of nameplate, manual rocker, instructions for use, red test clip and black test clip. The digital megohmmeter consists of a digital display, a test line connection jack, a backlight switch, a time setting button, a measurement knob, a range adjustment knob and other components.

Digital megger display, display symbols and descriptions

illustrate

This article does not discuss the advantages and disadvantages of hand-operated megohmmeters and digital megohmmeters, but simply popularizes knowledge!

Digital megohmmeter usage practice

The method of using a digital megohmmeter to detect the insulation resistance of a transformer is as follows:

1. Check the transformer under test

When using a digital megohmmeter to detect the insulation resistance of a transformer, it is necessary to detect the insulation resistance between the windings of the transformer and the insulation resistance between the cores.

2. Adjust the range of the digital megger and connect the test leads

Adjust the range of the digital megohmmeter to "500v", and the display will also show the range as 500v; then insert the red test lead into the "line" hole at the line end, and then insert the black test lead into the ground end "earth" hole.

3. Test the insulation resistance between the primary winding and the core of the transformer

Place the red test lead of the digital megohmmeter on any core of the primary winding of the transformer, place the black test lead on the metal shell of the transformer, and press the test button of the digital megohmmeter. At this time, the digital megohmmeter The display panel shows the insulation resistance as "500mω".

4. Test the insulation resistance between the secondary winding and the core of the transformer

Place the red test lead of the digital megohmmeter on any core of the secondary winding of the transformer, place the black test lead on the metal shell of the transformer, and then press the test button of the digital megohmmeter. At this time, the digital megohmmeter will The display panel of the ohmmeter shows that the insulation resistance is "500mω".

5. Test the insulation resistance between the primary winding and the secondary winding of the transformer

Place the red test lead of the digital megohmmeter on any core of the secondary winding of the transformer, and place the black test lead on any core of the primary winding of the transformer, and then press the test button of the digital megohmmeter. At this time, the display panel of the digital megohmmeter shows that the insulation resistance is "500mω".

When using a megohmmeter to measure the insulation resistance of a cable, when the voltage applied to the cable by the megohmmeter is 1000v, the insulation resistance of the cable should be above "1mω". If the applied voltage is 10kv, the insulation resistance of the cable The insulation resistance should be above "10mω", which indicates that the cable has good insulation performance. If the insulation performance of the cable cannot meet the above requirements, short circuit failure may occur during operation with the connected equipment.