Operating Mechanism For Circuit Breaker Research Articles

Contact Force Monitoring and Its Application in Vacuum Circuit Breakers

Condition monitoring of circuit-breaker (CB) operating mechanisms is one the most important aspects of predictive maintenance. This paper proposes a contact force monitoring scheme for 10 $\sim$ 35-kV vacuum CB. With specially designed force sensors and a signal-processing method, we can accurately find the instants of contact touch and separation. With the indirectly measured contact touch-and-separation instants, we can measure the opening speed, closing speed, and open gap over the travel of each phase. The accuracy of our online monitoring scheme is compared with the conventional offline methods that can directly obtain the instants of contact touch and separation by measuring the connectivity of the contacts. The results show that the accuracy of the scheme proposed in this paper is satisfactory and it can meet the engineering requirements of online condition monitoring of CBs. By introducing a set of new force sensors, some additional information that is useful for overall condition assessment of CB operating mechanism can also be extracted; this will help us to find new ways to improve our CB condition monitoring systems.

Trip-free reclosing circuit-breaker mechanism

THE DEMAND FOR ever higher interrupting capacities and ever shorter interrupting and reclosing times of power circuit breakers has presented a challenge to the designer of the circuit-breaker operating mechanism. The gauge of this challenge is the achievement of interrupting times as short as 3 cycles and successive reclosing times, without intentional time delay, as short as 15 cycles, all without sacrifice of simplicity and reliability.

Developing a Superspeed Trip-Free Reclosing Circuit-Breaker Mechanism [includes discussion

Circuit-breaker engineers are challenged by the demands for ever-increasing interrupting capacities of power circuit breakers, increases required as load growth and nation-wide system interconnections are planned. Within the past 10 years the maximum interrupting ratings of high-voltage circuit breakers has tripled and the ceiling is not yet in sight. These high interrupting capacities represent substantial increases in the duty imposed on the operating mechanism, for the magnetic forces alone imposed on the contacts of a circuit breaker multiply as the squares of the short-circuit current. Modern operating requirements which add to the duty of the circuit-breaker operating mechanism are the requirements for circuit clearing in 3 cycles and repetitive reclosing in intervals as fast as 15 cycles. These necessitate the control of accelerating and decelerating forces considered extreme a few years ago. With these new demands for operating requirements is a matching development in circuit breakers. This paper describes the development and design of a new operating mechanism offered to meet the advanced specifications of high-voltage circuit breakers. As specified, this mechanism is required to control the circuit-breaker contacts for circuit clearing in 3 cycles. Successive reclosing operations are to be completed in intervals as short as 15 cycles without intentional time delay. The operating mechanism continues to be mechanically trip-free during any operation and is suitable for application to the largest tank-type circuit breakers now listed in the standards. The methods used for satisfying these requirements are described.

New solenoid mechanism for magne-blast breaker

The existence of relatively high electromagnetic forces in circuit breakers when subjected to fault currents of appreciable magnitude has long been recognized. One of the problems in the design of a circuit-breaker operating mechanism is to provide smooth and effective closing performance, even though the breaker be closed against a short circuit and is thereby subjected to these high electromagnetic retarding forces during the final portion of the closing stroke. The greater the magnitude of the short-circuit current, the higher these electromagnetic retarding forces become and the more serious the effects of any tendency to “stall” or, worse, to reverse momentarily the closing motion of the contacts. This paper describes a solenoid mechanism with novel design features developed to operate a new Magne-Blast circuit breaker of high interrupting rating and capable of closing that breaker against fault currents as high as 80,000 amperes rms.