... 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 ... ,6kV,10kV,15kV,20kV,35kV,110kV,220kV5) standard transformer accuracy grade grade 0.01,0.02,0.05( specific accuracy grade can be chosen ...