I-t-e Imperial Corporation

Gould Inc.

Brown Boveri Electric Inc.

Lee A Davis

Peter Pang

A self-powered ammeter is disclosed. A metering circuit receives an a-c current to be tested and then generates a d-c voltage whose magnitude is proportional thereto. A display circuit receives the d-c metered voltage and provides a visual indication of the magnitude of the measured current. The current to be measured also drives a current transformer which, in turn, has an output burden circuit which produces a regulated power supply for the metering and display circuit components.

Self-powered ammeter

An electronic overcurrent detection and tripping circuit for circuit breakers is disclosed. The circuit includes an instantaneous trip circuit, a short time delay trip circuit, a long time delay trip circuit and a ground trip circuit. Each of the circuits is provided with adjustable ranges which can be set by suitable tap blocks or the like. A novel power supply is provided for the circuit which incorporates a unique series-connected zener diode and sensing resistor. The power supply circuit also provides sufficient power for tripping a magnetic latch of the circuit breaker whose current is being monitored. Each of the circuit functions can be disabled for purposes of tests by simply placing the function tap block pin in an appropriate test position.

Electronic overcurrent detection and tripping circuit

A solid state tripping circuit for sensing overcurrent conditions in a circuit connecting a power source to a load circuit and for controlling the operation of a circuit breaker in series in the circuit. The tripping circuit is responsive to different levels of current flow in the protected circuit to actuate the circuit breaker to the open condition after a variable time delay. The duration of the delay time is a function of the ratio of the overcurrent sensed to the rated circuit current. Energy for operation of the tripping circuit is supplied directly by the sensing circuit to eliminate a separate power supply.

Solid state tripping circuit

A static relay utilizing a resistance-capacitance network to provide a current-time characteristic which has an inverse relationship for appropriately controlling protective operations in power transmission and distribution networks. An integrated dual-threshold and clamp circuit is employed in the static relay to adjustably control the time delay characteristic of the network over a range of several orders of magnitude without altering the time delay wave shape or requiring matched components and incorporates linear time setting means to facilitate adjustment and usage of the static relay.

Integrated circuit linear time delay extender for static relays

A magnetic mechanism for resetting a magnetic target device by reversing the direction of flux in the device yoke without requiring the energization of an electrical reset circuit. A pivotable member is provided to hold the target reset mechanism captive in a position spaced from the target mechanism when the reset mechanism is not in use.

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Audubon, NJ, United States of America

Lee A Davis