According to the present practice of reactive power compensation and on load voltage regulation in substations

a technique of using voltage regulation and reactive power compensation separately is proposed. The reactive power is used as a key parameter

while the rate of voltage change before and after the switching of capacitors is compared as well as the bus voltage. The hardware is mainly composed of programmable computer controller （PCC）

instrument transformers

and the associated input and output circuits. Based on the advanced technology of control and data processing

and the object oriented methodology

a new reliable instrument is developed

which provides a new design method.