Dc resistance tachometer is an indispensable test project for transformer after handing in pick up overhaul and change sub-pick up switch. In general using traditional methods (bridge method and pressure drop method) measurement transformer winding group and dc resistance of large power inductance equipment is a time-consuming and time-consuming work. In order to change this situation shorten measurement time and reduce the work burden of test personnel huatian electric power developed Dc resistance rapid test instrument (hereinafter referred to as direct resistance instrument). Dc resistance tachometer adopts new power supply technology featuring stable performance rapid measurement compact volume easy to use High measurement precision and good data repeatability. Measurement transformer around the group and large power inductor dc resistance ideal equipment. Dc resistance tachometer meets the requirements of DL/ t845.3-2004 with national standard gb6587-86 "general outline of environmental test of electronic measurement instrument" and gb6593-86 "test rules of electronic instrument quality".