Insulation resistance measurement of Power Current Transformer

1. Cut off the switching power supply of the sample, disassemble or disconnect all the connections open to the outside world, and charge and discharge the sample to the ground. When charging and discharging, use special tools such as insulating layer rods, and do not touch the charging and discharging power lines with force.

2. The primary winding of the Power Current Transformer is accurately measured with a 2500V megohmmeter, and the secondary winding is accurately measured with a 1000V megohmmeter. During accurate measurement, the accurately measured windings are wired to the megohmmeter, and the non-tested windings are all short-circuited and grounded.

3. Use a dry and clean soft cloth to wipe off the stains on the surface of the outer insulating layer of the sample. When necessary, it should be cleaned with a moderate cleaning solution.

4. The terminal "E" on the megohmmeter is connected to the ground terminal of the sample, "L" is connected to the high voltage terminal, and "G" is connected to the shielding terminal. Use shielded cables and insulation shielding rods for connection. Keep the level of the megohmmeter steady. When the speed ratio of the megohmmeter is still rotating at a low speed, use the power line to connect the "L" and "E" terminals instantly, and the pointer should point to zero. When leading the way, the pointer of the speed ratio of the megohmmeter should point to "∞" when the speed ratio reaches the rated value. Then stop the rotation of the megohmmeter, connect the ground end of the megohmmeter to the ground wire of the sample, connect the high voltage end of the megohmmeter to shield the electrode connection wire, and hang the other end of the electrode connection wire in the air (not connected to the ground wire). sample), drive the megohmmeter again or connect the switching power supply, there should be no significant difference in the marking of the megohmmeter. Then stop the rotation of the megohmmeter, and shield the electrode connection wire to receive the precise measurement position of the sample.

5. The driver's megohm expresses the rated speed ratio, or connect to the megohmmeter switching power supply. After the pointer is stable (or 60s), load the grounding resistance value.

6. After loading the grounding resistance, first disconnect the electrode connecting wire leading to the high voltage end of the sample, and then stop the operation of the megger.

7. After disconnecting the megohmmeter, charge and discharge the wiring of the sample and ground it.

8. When measuring accurately, record the temperature, ambient humidity, climate conditions, experiment time and application instrument panel of the tested equipment.