Abstract: The phase of electrical current flowing through a power distribution network is sensed and fed to a computer. A transducer also detects the position and movement of an insulator rod used to mechanically open the contacts of a high voltage circuit breaker in the power distribution network. Signals indicative of insulator rod position and movement are also furnished to the computer. When it becomes necessary to open the circuit breaker contacts, the insulator rod movement and the electrical current phase are coordinated so that the contacts are carrying little, if any, current when they open. The fault-interrupting capacity of a circuit breaker is increased, while damage to the breaker contacts is reduced.

Abstract: The operation of energized substation circuit breakers in electrical power distribution systems is directly monitored. For each circuit breaker in a multi-phase breaker arrangement, the flow of electrical current is sensed. A signal is then formed for each phase representative of the sensed current flow. The signals so formed for the multi-phases are combined into a composite waveform for monitoring and diagnostic purposes. In the composite waveform, the signal for each phase of the circuit breaker is identifiable by its time relationship to others and by a distinctive voltage level.