| 摘要 |
A portable calibrator for d.c. circuit breakers is provided which produces a low voltage, short duration current test pulse of a current level sufficient to trip the breaker under test. The current pulse is produced by a high power, high frequency d.c. to d.c. converter which is controlled by lower power signals. A static switch controlled by the converter output provides current protection for the converter. A feedback loop including a current transformer connected in an output transformer circuit provides control of the test pulse. A non-inductive shunt connected in a negative test lead monitors the test pulse during the period of application thereof, the shunt being connected to a sample and hold read-out circuit which includes metering for indicating the peak current value. A timer interlocked with the metering ensures that sufficient time is provided for the operator to read current value.
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