With strong anti-electric field interference ability up to 2mA (50Hz), it is suitable for 500kV substation without dismantling wire to test insulation resistance of 500kV large-scale transformer. 2. The short-circuit current of test power 10mA. Be suitable for testing high capacity and high inductance. 3. Wide resistance range from 0.5MΩ ~ 200000MΩ. With high-resolution, having accurate readings. 4. Wide voltage range: 0.25kV, 0.5kV, 1kV, 2.5kV, 5kV, 10kV, 15 kV /20kV, you can smoothly adjust voltage from 0V to the desired value. 5. With timekeeping function, remind users to record, and analyze absorptance and polarization index of measured target.