High voltage output acousto-optic warning Switch gear error warning Automatic release measured line capacitance power Insulation resistance test current accords with IEC348 standard requirement Large LCD display: the word 22mm, the maximum display number 1999 Insulation resistance measurement level output voltage: 250V, 500V, 1000V Insulation resistance measuring range: 0 - 2000M DC voltage measurement range: 0 - 1000V The measuring range of AC voltage: 0 - 750V