ZN85-40.5/2000-31.5 indoor high voltage vacuum circuit breaker (hereinafter referred to as circuit breaker) is suitable for three-phase AC 50Hz, rated voltage 40.5KV power system, and can be used in industrial and mining enterprises, power plants and substations as load current, overload current and fault current. The circuit breaker and operating mechanism are arranged up and down to reduce the depth of the circuit breaker effectively. The three-phase arc extinguishing chamber and the connected charged body are separated by three independent epoxy resin insulated tubes, which constitute a composite insulation structure. The circuit breaker can meet the requirements of air distance and climbing distance under normal operation conditions, and effectively reduce the volume of the circuit breaker. The vacuum arc extinguishing chamber of the main electric circuit and the static-electric connection are installed in the insulated cylinder, so that the phase spacing is only 300mm. The electrical connection of the main circuit adopts fixed connection, which has high reliability. The insulation barrel is mounted above the breaker frame. The spring operating mechanism specially designed for this new type of circuit breaker is installed in the framework of the circuit breaker. Its structural characteristics are more suitable for the layout of the circuit breaker up and down, and become an integral part of the overall structure of the circuit breaker. The mechanism design is simple, and the output curve and its performance are more suitable for the characteristics and requirements of 40.5kV vacuum circuit breaker. The overall layout is reasonable, beautiful and simple. Compact size, flexible operation, reliable electrical performance, long service life, easy maintenance, maintenance free mechanism characteristics. The circuit breaker is suitable for frequent operation and many occasions and places with harsh operating conditions. 1. The circuit breaker adopts the arc extinguishing chamber on the upper part, and the structure of the whole structure under the mechanism is favorable for debugging; 2. It adopts composite insulation structure of air and organic materials, which is compact in design and light in weight; 3. It can be equipped with the vacuum interrupter of Cutler-Hammer Company of the United States and the domestic ZMD vacuum interrupter. The two arc extinguishing chambers adopt the longitudinal magnetic field arc extinguishing, low interception and good asymmetric breaking performance. 4. Simple spring operating mechanism, 10,000 operations free of maintenance. 5. Screw drive mechanism, labor-saving, stable, self-locking performance.1. Ambient air temperature: -5~+40 and the average temperature should not exceed +35 in 24h. 2. Install and use indoors. Altitude above sea level for operation site should not exceed 2000M. 3. Relative humidity should not exceed 50% at max temperature +40. Higher relative humidity is allowed at lower temperature. Ex. 90% at +20. But in view of the temperature change, it is possible that moderate dews will produce casually. 4. Installation gradient not exceed 5. 5. Install in the places without fierce vibration and shock and the sites insufficient to erode the electrical components. 6. Any specific requirement, consult with manufactory.