The SES1-12 ring network cabinet produced by our company is applied to the main unit switch of medium voltage distribution network solid composite insulation ring network. In the same power supply unit, three phases a, B and C are composed of three independent modules, which can provide several combinations for the distribution network. Composite insulation has load switch, circuit breaker and many kinds of operation functions such as manual, electric, etc. through the selection of a variety of intelligent controllers such as FTU and other related equipment, it can achieve different degrees of control, measurement and protection functions.