Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and for initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a fault indicating circuit arrangement energized by a backup energy source following interruption is also included as well as circuit arrangement for preventing interference to the display and operating circuits during power-up and power-down conditions.

Abstract: A molded case circuit breaker includes a solenoid control circuit for controllably energizing a solenoid to actuate a motor operator to automatically move a handle of the circuit breaker to change the operative condition of the circuit breaker. The control circuit includes a monostable multivibrator that supplies an electrical pulse to the solenoid upon the receipt of a switching initiation signal. The time duration of the electrical pulse is controlled to be sufficiently long to assure proper operation of the solenoid and is determined by a timing circuit coupled to the source of operating voltage for the solenoid. If the operating voltage decreases, the time required to charge the timing circuit increases, increasing the duration of the electrical pulse of the solenoid to assure proper operation under low voltage conditions.

Abstract: A circuit interrupter includes a circuit breaker mechanism having a trip coil energized by a current transformer to separate the contacts upon command of a microcomputer-based trip unit during overcurrent conditions. A bimetallic normally-open thermal switch is mounted on the internal conductors of the breaker and is connected in parallel with the trip unit to energize the trip coil when the conductors overheat. The thermal switch is also connected to the interrupt terminal of the microcomputer to cause appropriate display and alarm information upon activation of the thermal switch.

Abstract: A circuit interrupter includes a microcomputer-based trip unit, and a display and control panel comprising a numeric display device and a plurality of legends associated with light-emitting diodes. The trip unit presents a sequential display of numeric values of associated circuit electrical parameters and time-current trip characteristic setting values, with the currently visible numeric quantity being identified by an energized light emitting diode and associated legend. The control panel also includes a test switch for initiating a test operation and a potentiometer for selecting a desired simulated fault current value for the test operation. The test capability is provided simultaneously with normal circuit breaker operation which maintains full protection of the associated circuit. A short-delay feature is provided having a selectable i.sup.2 t characteristic with adjustment of both pick-up and time parameters.

Abstract: A circuit breaker includes a microcomputer-based trip unit, and a remote indicator unit and power supply. The trip unit includes an optically-coupled data output system and means for generating a pulse code containing cause-of-trip information and excess demand alarm information. The remote indicator unit includes an optically coupled input circuit and a plurality of light emitting diodes to indicate cause of trip and excess demand alarm information upon receipt of an appropriate pulse code pattern. The remote indicating unit also includes relays to provide control of external alarm circuitry upon receipt of cause of trip and demand alarm information. The remote indicator unit further includes a power supply for supplying operating power to the remote indicator unit and to the trip unit. The power supply is powered both from an external AC line connection and from internal rechargeable batteries.

Abstract: This concerns an undervoltage relay device for a circuit breaker system with a time delay feature. Two lines of the electrical system to be protected are monitored by a transformer. The output of which is rectified and provided to a capacitive element which, among other things, filters the signal. The capacitive element may comprise a single capacitor or combination of capacitors. The combination chosen is the function of the amount of time delay desired. If the voltage across the monitor lines drops below a predetermined value, the voltage level across the capacitive element begins to drop accordingly. This decreasing voltage signal is provided by way of a voltage divider to one input terminal of a comparator. The other input terminal of which is maintained at a reference voltage. When the signal voltage drops below the reference voltage, the comparator shift state thus causing an undervoltage relay coil to be deenergized.

Abstract: A circuit breaker includes a microprocessor-based trip unit and a designator circuit including a plurality of jumper positions. Each jumper position corresponds to one digit of a four digit style number specifying which of a plurality of optional functions and features are incorporated in the specific trip unit. Each jumper position is a multitap voltage divider. Selection of one tap on each of the jumper positions causes a set of four analog voltages to be supplied to the trip unit. An analog-to-digital converter converts the analog voltages to a series of digital representations which are interpreted by the microcomputer as a style number used to command execution of a discrete set of instruction groups, with each instruction group corresponding to one of the optional functions and features.

Abstract: A circuit interrupter includes a microprocessor-based trip unit, a numeric display, and a plurality of potentiometers each associated with one parameter of the time-current trip characteristic of the circuit interrupter. The trip unit provides a sequential display of the present setting values of the time-current trip characteristic parameters. Adjustment of any of the potentiometers is operable to interrupt the sequential display and to cause the present setting of the parameter associated with the adjusted potentiometer to be displayed. Adjustment of the potentiometer to either limit of its travel causes the most conservative setting value for that parameter to be selected. A hysteresis feature is provided to require a significant adjustment of the potentiometer before a different parameter setting will be selected.Although the potentiometers are continuously variable, operator adjustment thereof results in the selection of one of eight predetermined discrete values stored in the trip unit.

Abstract: A circuit interrupter includes an interchangeable trip unit removably disposed in the circuit interrupter housing and connected between a current transformer and a trip mechanism. The trip unit contains electronic circuitry for activating the trip mechanism to open the contacts upon detection of overload current therethrough and includes rejection means provided to ensure that only a trip unit having circuitry compatible with the electrical characteristics of the circuit interrupter can be inserted into the housing. The rejection means comprise a plurality of pins mounted within the housing and extending into the recess to be occupied by the trip unit. The pins are arranged in a pattern unique to all circuit interrupters having identical electrical characteristics. A pattern of holes is provided in the enclosure of the trip unit, the hole pattern being unique to trip units having identical electrical characteristics.

Abstract: A circuit interrupter includes an adjustable trip unit for tripping the circuit breaker to the open circuit position upon overload current conditions. The trip unit includes a shorting plug adjuster comprising a pair of connecting pins electrically connected together and insertable into cooperating sockets in the trip unit housing. One of the pins is common to all adjustment positions and is of greater length, having a retaining clip at the end thereof to permit the adjuster to be partially withdrawn, pivoted about the common pin, and inserted into the desired position. The adjuster comprises a flange which covers the trip unit panel socket in all positions, thereby providing protecting against dust and other contamination. The adjuster is cheaper and more reliable than the prior art, providing increased protection against shock, vibration, and contact bounce.

Abstract: A circuit interrupter is provided with a trip unit removably inserted into the housing of circuit interrupter through the cover thereof. The trip unit is secured to the housing by spring clips mounted therein cooperating with recesses in the enclosure of the trip unit to permit insertion of the trip unit with the cover installed but preventing removal of the trip unit without prior removal of the circuit interrupter cover.

Abstract: The disclosure describes a device for detecting undervoltage conditions on multi-phase alternating current circuits which senses the voltage on the phase having the highest instantaneous positive voltage. A differential between pickup and dropout voltage is provided. Also provided is a delayed pickup following a return to normal voltage on the circuit being monitored.