The UNI-T Insulation Resistance Meter UT501B is a digital tester designed for measuring insulation resistance in electrical equipment and household appliances. It can measure high resistances up to 5 GΩ with test voltages of 250V, 500V, and 1000V. Additionally, it measures AC voltage up to 600V and low resistance down to 0.01 Ω.   

A 2000-count LCD display with backlight, auto range, data hold, low battery indication, overload indication, auto discharge, and high voltage warning. It also performs Polarization Index (PI) and Dielectric Absorption Ratio (DAR) tests, which are useful for assessing the quality of insulation over time. The UT501B is a reliable tool for electrical maintenance, testing, and inspection, ensuring the safe and accurate operation of various electrical systems.