The capacitive voltage divider is composed of a porcelain sleeve and a number of series capacitors installed in it. The porcelain sleeve is filled with insulating oil that maintains a positive pressure of 0.1MPa, and a steel bellows is used to balance different environments to maintain the oil pressure. The capacitive partial pressure can be used as a coupling capacitor Connect the carrier device. The capacitive voltage transformer is mainly composed of a capacitive voltage divider and a medium voltage transformer. The medium voltage transformer is composed of a transformer installed in a sealed oil tank, a compensation reactor and a damping device, and the space at the top of the oil tank is filled with nitrogen. The primary winding is divided into a main winding and a trimming winding, and a low-loss reactor is connected in series between the primary side and the primary winding. Due to the nonlinear impedance and inherent capacitance of the capacitive voltage transformer, ferromagnetic resonance is sometimes caused in the capacitive voltage transformer, so the damping device is used to suppress the resonance. The damping device consists of a resistor and a reactor, which is connected across the secondary winding Normally, the damping device has a very high impedance. When the ferromagnetic resonance causes an overvoltage, the reactor is saturated with only a resistive load before the medium voltage transformer is affected, so that the oscillation energy is quickly reduced. Capacitive voltage transformers are voltage transformers that draw voltage from series capacitors and then use transformers as transformers to act as voltage sources for metering, relay protection, etc. Capacitive voltage transformers can also couple carrier frequencies to transmission lines for long distances Communication, remote measurement, selective line high frequency protection, remote control, teletype, etc. Therefore, compared with the conventional electromagnetic voltage transformer, the capacitive voltage transformer can prevent the ferromagnetic resonance caused by the saturation of the voltage transformer iron core, and has many advantages in economy and safety.