UHT1 is a hatchway type UHF sensor designed to detect partial discharge (PD) in the oil paper edge transformer tank. There is no UVS 610 sensor drain valve. It is permanently installed on the surface of the transformer tank, providing you with an oil-tight dielectric window permeable to electromagnetic waves. The UHT1 sensor measures PD in the ultra-high frequency (UHF) range to suppress external noise, such as corona on high-voltage lines.