S420 High Voltage Insulation Tester or named Megohmmeter、Digital Megohmmeter Insulation Resistance Tester、High Voltage Insulation Resistance Tester etc. Specialize in laboratory or various of construction area。The instrument has the functions of LCD large screen gray-white backlight display, data storage, data reference and so on. At the same time, it can automatically calculate the absorption ratio(DAR) and polarization index(PI), and automatically store the data of 15 seconds, 30 seconds, 1 minute and 10 minutes. High resolution, easy to operate, easy to carry, accurate, reliable, stable performance, strong anti-interference ability. Moreover, it has the structure of shockproof, dust-proof and moisture-proof. It is a common and indispensable instrument for telecommunication, electric power, meteorology, machine room, oil field, mechanical and electrical installation and maintenance, as well as the industrial enterprise departments using electric power as industrial power or energy. It is suitable for measuring the resistance of various insulating materials and the insulation resistance of transformers, motors, cables and electrical equipment. Digital insulation resistance meter is composed of medium and large scale integrated circuits, including high-precision micro current measurement system, digital boost system and automatic discharge circuit. Only a high voltage line and a signal line are needed to connect the measured object to measure. The measurement is carried out automatically, the results are displayed on the large screen, and the results are stored. The rated output test voltage range is 250V ~ 5000v, and the insulation resistance measurement range is 0.01M Ω ~ 5.00t Ω. The DC voltage measurement range is 0v-1000v DC, and the AC voltage measurement range is 0v-750v AC.