1). 6 to 20k power distribution equipment generally uses oil immersion insulation structure. Resin pouring insulation structures can be used in high-voltage switching equipment or in places with narrow placements. When zero-order voltage is required, a three-phase, three-poster voltage transformer is generally used. 2). 35 to 110kV power distribution devices generally use oil-immersed insulation structure electromagnetic voltage transformer. (4) The voltage transformer is paralleled with the grid. When the system is shorted, the voltage transformer itself is not affected by the short-circuit current, so thermal and dynamic stability is not verified.