A permanent magnetic actuator with scheduled stroke curve for vacuum circuit breakers
The load characteristics of vacuum circuit breakers (VCB) are very close to the output characteristics of permanent magnetic actuator (PMA). The combination of PMA and VCB facilitates the development of phase-controlled switching technology because of its controllability. The operation time dispersion of PMA is very small, but when the actuator is impacted by the change of environment or its components, its dispersion will be unfit for phase-controlled switching. A new type of actuator driving system for PMA was proposed, which was combined with sensors, embedded system and capacitor controlled by high-current power electronic devices. The iron core trajectory of PMA was measured by a displacement sensor and compared to a scheduled action curve, the environment temperature is from a temperature sensor and the current from a Hall current sensor, then compensation to displacement was made based on the adaptive control algorithm and history data in order to match the optimal stroke curve of vacuum circuit breakers. In different conditions, the test results show that the stroke curve was in keeping with the scheduled curve and the operating time dispersion of VCB meets the requirement. The new type actuator driving system can supply an easy-controlled, constant-operating- time execution unit to controlled switching.
Synchronous MV circuit-breaker with magnetic drive and electronic control
n 1997 ABB introduced a new series of medium-voltage circuit-breakers with a magnetic drive instead of a spring-based operating mechanism [1]. This solution soon proved to be much more reliable than its predecessor. Following up on the success of the magnetic drive, ABB has now developed a new controlled switching technology which will allow the closing and opening operations to be synchronized with the power network. Synchronous switching, also called ‘point on the wave’ switching, is a wellknown concept [2,3], being used particularly in high-voltage applications to avoid or reduce switching transients and their power network disturbances. The synchronous circuit-breaker has several important advantages over conventional switching equipment, eg: • Transient stresses acting on network components are strongly reduced, enhancing reliability. • The network exhibits a higher power quality. • The electrical lifetime and performance of the circuit-breaker are improved. • The network design can be simplified, thereby reducing the cost of the overall system.
A VACUUM CIRCUIT-BREAKER WITH PERMANENT MAGNETIC ACTUATOR AND ELECTRONIC CONTROL
Vacuum circuit-breakers have obtained a high level of performance, reliability and safety. This is mostly owed to the advantages of current interruption in vacuum. However, the design of the mechanical drive, which has already been applied e.g. in minimum oil-breakers, has hardly been changed. With the introduction of an actuator with permanent magnetic limit positions and electromagnetically controlled motion, the next generation of vacuum circuit-breakers is launched promising an increase in reliability and endurance. The operation of the circuit-breaker is controlled by an electronic device implementing interlocking, signaling, releases and selfdiagnosis. The electronic control and supply requires a somewhat different approach to applications compared with a conventional circuit-breaker. The experience with frequent operations reaching 100000 CO is promising.