| 摘要 |
A circuit breaker including separable contacts, an operating means for opening and closing the contacts and a trip coil responsive to a static control circuit for tripping the circuit breaker when instantaneous power in one of the phases of a three phase alternating current circuit exceeds adjustable predetermined levels for adjustable predetermined times as well as ground faults. A separate non-saturated iron core current transformer detects the current in each of the phases independently and powers independent cascaded current transformers having outputs of the same polarity connected to form OR circuits and provide a voltage signal correlated with the instantaneous current in a single one of the protected lines with the highest signal back biasing the others. This signal is amplified and delivered to a plurality of independent solid state adjustable time delay circuits for instantaneous time delay, short time delay and long time delay actuation of the trip coil dependent upon the extent to which the current levels in the protected line providing the signal exceeds a predetermined level of line current. Ground fault protection is also provided.
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