... apparatus console2) HES digital transformer calibrating apparatus series3) HLS precise current transformer series4) HJS precise voltage transformer series5) FY current (voltage) transformer load box series6) Primary ... ) voltage measurement range 3kV,6kV,10kV,15kV,20kV,35kV,110kV,220kV5) standard transformer accuracy grade grade 0.01,0.02,0.05 ...