Westinghouse Electric Corporation

John T Wilson

Joseph C Engel

Robert Tracy Elms

John A Wafer

Gary F Saletta

James P Ellsworth

Wardell Gary

Walter W Lang

Bernard J Mercier

A circuit breaker includes a digital electronic trip unit having a microprocessor. The front panel of the trip unit includes a potentiometer connected across a reference voltage, and a numeric display device. The potentiometer is adjusted by an operator to enter a value of a parameter defining the time-current characteristic of the circuit breaker. An analog-to-digital converter receives the voltage supplied by the potentiometer and converts it to a digital quantity for use by the microcomputer in performing limit checks with the current flow through the contacts of the breaker. The microcomputer formats the converted digital value of the potentiometer voltage and supplies it to a front panel-visible numeric display so that the value of the potentiometer setting as interpreted by the microcomputer in defining the time-current trip characteristic is presented on the numeric display to provide real-time feedback to the operator as he adjusts the parameter value.

Circuit interrupter with digital trip unit and means to enter trip

A circuit breaker includes a microprocessor-based trip unit having an optically coupled data input/output system. A pulse transformer receives input pulses generated by the execution of instructions in said microcomputer and supplies these pulses to a plurality of optical isolators, thereby reducing the power requirements of the optically isolated interface system to a value sufficient to allow complete operating power to be supplied to the trip unit and the data input/output system from the sensing current transformers within the circuit breaker housing.

Circuit interrupter with digital trip unit and optically-coupled data

A circuit interrupter includes a digital trip unit containing a microprocessor. The circuit interrupter also includes current transformers for sensing current flow through the contacts of the interrupter and for providing operating power to the trip unit. The current transformers monitoring current flow through the breaker and control potentiometers receiving operator-entered values of the product of line voltage and power factor are connected to the microprocessor to supply it with the values needed to compute real power flow through the interrupter and to display the numeric value of this power flow. The power flow is compared to an operator-entered limit value of peak demand power, and an alarm signal is generated whenever power flow exceeds the limit value peak demand. Integration capability is also provided to calculate energy flow through the contacts in megawatt hours and to present the numeric value of this energy flow.

Circuit interrupter with energy management functions

A circuit breaker of the type having short delay and long delay tripping modules. Separate signals are provided as external outputs from the latter modules. Furthermore, inputs are provided to the latter modules for disabling the normal operation thereof. The above-mentioned breaker also includes an instantaneous tripping circuit. If the amount of overload current is sufficiently high, an instantaneous tripping operation takes place. If the overload current is relatively lower than that which would necessitate instantaneous tripping, short delay or long delay tripping will take place. If the current then continues to increase to a sufficiently high value, the circuit breaker will operate through the instantaneous tripping circuit. One of the above-mentioned circuit breaker apparatus can be interconnected with others so that one circuit breaker in an electrical line to be protected will open and provide output signals which will prevent the short delay and long delay of other circuit breakers in the system from operating thus saving some of the protected system from shut-down.

Electrical apparatus including interlocking circuit for short-time delay

A self-powered self-contained ground fault protective device including a current monitor, an electronic circuit for amplifying the output of the current monitor, and a relay connected to the amplifying circuit and adapted to operate whenever ground fault current through the current monitor rises above a predetermined level. The current monitor, amplifying circuit, and relay are all supported and enclosed by a molded insulating housing.

Ground fault protective device

A self-powered self-contained ground fault protective device including a current monitor, an electronic circuit for amplifying the output of the current monitor, a relay connected to the amplifying circuit and adapted to operate whenever ground fault current through the current monitor rises above a predetermined level, and an interchangeable rating plug including means for activating a circuit board switch. The current monitor, amplifying circuit, and relay are all supported and enclosed by a molded insulating housing. The rating plug is inserted into a socket on the exterior of the housing.

Self-powered apparatus for indicating the existence of a fault in any of a plurality of conductors in an multiconductor electrical distribution system. The plurality of conductors pass through the window of a closed loop core structure current transformer, and the current transformer has a power output and a signal output. The power output is connected to, and drives, fault indicating means and starting means. The starting means initiate operation of control signal translation means which are connected to the current transformer signal output. Also included are transmission means connected to the control signal translation means and to prevention means incorporated within the indicating means, and the transmission means transmit the control signal from the signal translation means to the prevention means. The indicating means are responsive to operation of the prevention means, such that only when the control signal is transmitted to the prevention means will the indicating means be allowed to operate. The entire apparatus is powered only during the existence of a fault, and derives its power by the fault's causing current to flow within the current transformer. The apparatus may also be utilized in a current-monitoring function for a single conductor.

Indicating apparatus

A circuit breaker including a solid-state circuit for providing regulated current to operate a holding coil for an undervoltage release mechanism. An alternating current control line feeds a full wave bridge rectifier in the control circuit to provide pulsating direct current to a reference voltage supply circuit, a current regulating circuit, and the holding coil of an undervoltage release mechanism. The current regulating circuit comprises two series connected units of an integrated circuit quad current differential operational amplifier. The output of the second unit controls the base current of a regulating transistor which is series connected to the holding coil. The reference voltage supply circuit includes a transistor connected as a variable resistor to provide operation of the circuit over a wide range of input voltages without excessive heat generation.

Circuit breaker including undervoltage release mechanism and control

A timing device utilizing a transistor and silicon controlled rectifier to provide a momentary relatively high voltage for the solenoid coil of a tripping device which is part of an undervoltage detecting and tripping circuit to thus energize the coil to allow closing of a circuit breaker which is controlled by the undervoltage device when low voltage which originally caused the circuit breaker to trip is no longer present on the line to be protected by the circuit breaker. The relatively high voltage changes to a normal value shortly thereafter.

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Beaver, PA, United States of America

John T Wilson