ZN28-12/630A old oil-minimum circuit breaker replaced with high-voltage vacuum switch

ZN28 indoor high-voltage vacuum circuit breaker is a type of indoor high-voltage switching equipment with a rated voltage of 12KV and below. It is mainly used for the protection and control of electrical facilities in industrial and mining enterprises, power plants and substations, and is especially suitable for scenarios with frequent operations and high-load breaking.

Its working environment must meet the conditions of an altitude below 2000 meters, a temperature ranging from -15℃ to +40℃, no significant pollution and severe vibration, etc. This circuit breaker adopts a frame structure and needs to be used with an external operating mechanism. It is equipped with core components such as a middle-sealed longitudinal magnetic field vacuum interrupter, main shaft, opening spring and oil buffer inside. The static and dynamic brackets are connected by insulators with large creepage distance, and the front end is provided with incoming and outgoing line terminals. The overall structure has high rigidity. Its working principle relies on the longitudinal magnetic field design, which makes the arc evenly distributed on the contact surface during the opening process, reducing the arc voltage and energy loss, thereby improving the short-circuit current breaking capacity and the electrical life of the equipment.

Product structure: It does not have an operating mechanism itself, and must be matched with a suitable operating mechanism when in use. The middle-sealed longitudinal magnetic field vacuum interrupter, main shaft, opening spring, oil buffer and other components are installed in the frame. The rear end of the frame is provided with mounting holes for the fixed installation of the circuit breaker. Six insulators with large creepage distance are horizontally installed on the front of the frame. The upper insulator fixes the static bracket, and the lower insulator fixes the dynamic bracket. The front parts of the static and dynamic brackets also serve as incoming and outgoing line terminals. The vacuum interrupter is installed between the static and dynamic brackets. The main shaft is connected with the moving conductive rod of the vacuum interrupter through an insulating pull rod and a crank arm. A large creepage distance insulating rod is also installed between the static and dynamic brackets to connect the two into one, improving the overall rigidity. 3. Working principle: The vacuum circuit breaker is matched with a middle-sealed longitudinal magnetic field vacuum interrupter. When the moving and static contacts are opened under the action of the operating mechanism, a vacuum arc will burn in the contact gap and extinguish when the current crosses zero. Due to the special structure of the contacts, an appropriate longitudinal magnetic field will be generated in the contact gap during the arcing time. This magnetic field can make the arc evenly distributed on the contact surface, maintain a low arc voltage, and enable the vacuum arc extinguishing chamber to have a high post-arc dielectric strength recovery speed, small arc energy and low electrical corrosion rate, thereby improving the short-circuit current breaking capacity and electrical life of the circuit breaker.