How smart circuit breakers work

The intelligent circuit breaker is a new circuit breaker secondary system using microelectronics, computer technology and new sensors. Its main feature is that the execution unit is composed of power electronics technology and digital control device, which replaces the auxiliary switch and auxiliary relay of the conventional mechanical structure. The new sensor works in conjunction with the digital control unit to independently collect operational data, detect equipment defects and faults, and send an alarm signal before the defect becomes faulty in order to take measures to avoid accidents. The intelligent circuit breaker realizes the electronic operation, the mechanical energy storage is the capacitor energy storage, and the mechanical transmission is the direct drive of the frequency converter through the motor, and the reliability of the mechanical system is improved.

The intelligent circuit breaker has been developed accordingly. The circuit breaker with intelligent operation function is based on the existing circuit breaker and introduces the intelligent control unit. It consists of three basic modules: data acquisition, intelligent identification and adjustment device. The intelligent identification module is the core of the intelligent control unit. The microcomputer control system composed of the microprocessor can automatically identify the power grid where the circuit breaker is located during operation according to the grid information collected before the operation and the operation signal sent by the main control room. According to the results of the simulation analysis of the circuit breaker, the appropriate switching and closing motion characteristics are determined, and the adjustment information is sent to the actuator. After the adjustment is completed, the switching signal is sent out. The data acquisition module is mainly composed of new sensors. The data of the power grid is provided to the intelligent identification module as a digital signal for processing analysis; the actuator is composed of a component capable of receiving quantitative control information and a driving actuator for adjusting parameters of the operating mechanism to change each operation The sporting characteristics of the time. In addition, display modules, communication modules, and various detection modules can be added as needed to expand the intelligent function of the intelligent operation circuit breaker.

The basic working mode of the intelligent circuit breaker is to automatically select the operating conditions of the operating mechanism and the arc extinguishing chamber according to the different fault currents monitored. If the normal running current is small, the brake is opened at a lower speed. When the system short-circuit current is large, The higher speed is opened to obtain the opening effect on the electrical and mechanical properties.

This intelligent operation requires the circuit breaker to have controllability in the mechanism action time. The pneumatic operating mechanism, hydraulic operating mechanism and spring operating mechanism commonly used in circuit breakers have large control time dispersion due to factors such as intermediate conversion medium, and their motion characteristics are difficult. Achieve the desired controllable state. The circuit breaker adopting the electromagnetic operating mechanism utilizes the technologies of capacitor energy storage, permanent magnet holding, electromagnetic driving, electronic control, etc., when the mechanism determines that there is only one moving part, there is no intermediate conversion medium, and the closing and closing characteristics are only related to the coil parameters, and can pass Microelectronics technology to achieve microsecond control, through the speed characteristics control to achieve intelligent operation of the circuit breaker.

The working process of the intelligent operation circuit breaker is: when the system failure is issued by the relay protection device or the operation signal is sent by the operator, the intelligent identification module is first activated to determine the working condition of the current circuit breaker, and the adjustment device is Different quantitative control information is issued and the parameters of the operating mechanism are automatically adjusted to obtain the motion characteristics suitable for the current system operating state, and then the circuit breaker is actuated.