Abstract: Phase reversal switch apparatus for a three-phase high-current isolated phase bus circuit includes a non-reversing phase switch, and two groups of two reversing phase switches. The apparatus also includes a phase reversal mechanism having a rotatable operating shaft with a drive lever, a non-reversing lever, and two reversing levers coupled thereto. Locking and drive couplings are selectively engaged with the levers and operated by a shift actuator and a switch actuator to selectively operate the non-reversing switch and the first and second reversing switches to effect a phase sequence reversing operation in a secure and efficient manner.

Abstract: Unidirectional rotation of a register is produced by a ratchet assembly having a pivoting pawl member having two diverging wire segments, each of which discretely engages either of two sets of ratchet teeth. A transfer means couples input rotations of the rachet assembly in a false registering direction so as to produce rotations of the assembly output in a true registering direction.

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 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.

Abstract: An automatic trip device for a circuit breaker includes a U-shaped stationary iron core disposed around a current-carrying conductor. The stationary core includes a semicircular recess on one leg thereof having V-shaped bearing surfaces formed at each end of the recess. A movable iron core is positioned across the legs of the stationary core and includes semicircular projection fitted into the recess of the stationary core. A shaft extends through the projection and pivots at each end in one of the V-shaped bearing surfaces. Tension springs connected between the stationary core and one end of the movable core produce opening rotational bias on the movable core. Electromagnetic force produced by an over-current flow through the conductor causes closing rotational movement of the movable core. The disclosed construction results in elimination of undesireable sound vibrations produced in prior art devices under conditions of current flow below overload level.

Abstract: A telescoping isolated phase bus disconnect switch includes a cylindrical outer housing at ground potential, a pair of coaxial fixed inner conductors at high potential, and a telescoping coaxial movable inner conductor bridging the two fixed inner conductors to perform a switching function. The movable inner conductor is supported on insulating means extending through the housing and mounted upon a movable carriage outside of the housing. The carriage is operated by a drive motor and mechanical linkage both located outside of the housing. The mechanical linkage produces a variable mechanical advantage, increasing its mechanical advantage over the movement range of the switch as the required closing force increases.

Abstract: 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.

Abstract: 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.

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: 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 breaker includes a microprocessor-based trip unit and a power supply for supplying operating power to the trip unit and the trip coil of the circuit breaker from either the internal current transformers of the circuit breaker or a plurality of external sources. The trip unit includes a numeric display for displaying a sequential series of parameter values under normal conditions. Under low-power conditions, the power supply provides pulses of operating power sufficient to enable the trip unit to execute all of its limit check functions and present a flashing display of a single parameter value.

Abstract: An oil-filled distribution transformer having a primary disconnect switch disposed within the housing and utilizing two movable bridging contacts and four stationary contacts for completing a series circuit therethrough. The switch includes a trip mechanism, a bimetal element isolated from the current path through the switch and responsive to the temperature of the oil to activate the trip mechanism upon overtemperature condition, and a float mechanism attached to the switch and cooperating with the trip mechanism so that the float assembly will activate the trip mechanism when the oil level within the housing drops below a predetermined value.

Abstract: A regulated DC power supply has a converter having a plurality of switches which, upon proper regulation of their conduction, rectify an AC current. The converter produces a current feedback signal. A reference generator produces a plurality of adjustable reference signals each representative of one value of a load current and produces a predetermined, standby, reference signal representative of a standby load current. One of the adjustable reference signals, the standby reference signal, and the current feedback signal are added to produce a control signal. The control signal is compared to a signal representative of the AC source voltage. Firing signals, used to regulate the conduction of the switches, are produced in response to the existence of a predetermined relationship therebetween. In the event that all of the adjustable reference signals have a value of zero for a predetermined period of time, the firing signals will be inhibited from regulating the conduction of the switches.

Abstract: A circuit breaker having separable contacts and a releasable trip mechanism operable upon overcurrent conditions to automatically separate the contacts includes a moveable arm stop connected to the releasable mechanism for limiting travel of the moveable contact in the open circuit position. The moveable arm stop includes a cam portion having an extended surface to limit travel of the moveable contact and establish a first contact separation distance when the trip mechanism is latched, and a flat surface limiting travel of the moveable contact to establish a second, greater contact separation distance when the trip mechanism is released.

Abstract: An electrical distribution switchboard including a multiphase horizontal main bus and a multiphase vertical riser bus. A plurality of tie members are provided, one tie member being connected to each vertical phase member. Each horizontal phase conductor is connected to the tie member of its corresponding vertical phase conductor so as to symmetrically locate the top and bottom of each tie member above and below the horizontal centerline of the horizontal main bus, allowing the vertical riser bus to be fed at its electrical and geometric center.

Abstract: A circuit breaker comprises an adjustable trip unit having electronic circuitry for initiating a tripping command upon detection of overcurrent conditions. The trip unit includes an externally accessible interchangeable plug-in rating adjuster removably supported on the housing of the circuit breaker by a threaded rod and tube. An interlock mechanism cooperates with the trip bar of the circuit breaker and secured mechanism to insure that only when a compatible rating adjuster is properly seated in the housing and the threaded rod is completely engaged within the threaded tube will the circuit breaker mechanism be removed from the trip-free condition.

Abstract: A telescoping high current disconnect switch for isolated phase bus includes a pair of axially spaced cylindrical fixed conductors insulatingly mounted within a cylindrical aluminum housing. An aluminum telescope section is coaxial with the fixed conductors and is insulatingly mounted upon a plurality of rollway pillow blocks each containing ball bearings. The pillow blocks are supported by guide rails of austenitic non-ferromagnetic stainless steel which are attached to the interior surface of the housing. The telescope section is axially movable along the guide rails to bridge the fixed conductors, such movement causing the ball bearings to cold-form grooves in the rails, whereby portions of the rails are work-hardened.

Abstract: A current limiting circuit interrupter includes two parallel pivoting contact arms carrying contacts at the ends thereof. The upper contact arm is pivoted upon a carriage which is in turn pivotally mounted upon a mechanism frame. A latch rod is movably secured in arcuate slots in the sides of the mechanism frame. When the circuit interrupter is in the closed circuit position, a pair of springs connected between the latch rod and the carriage urges the latch rod against a reaction surface of the upper contact arm to provide contact closing pressure. Upon occurrence of severe overload current conditions, the upper contact arm pivots upon the carriage, moving the latch rod within the arcuate slots to release the contact closing pressure, allowing the springs to move the latch rod against a latching surface of the upper contact arm to latch the upper contact arm in the open circuit position.

Abstract: A molded case circuit breaker includes separable contacts, a conventional operating mechanism, and means for magnetically stretching the arc upon contact separation to provide current limiting action. In a first embodiment, the arc stretcher comprises three separate stacks of spaced parallel U-shaped magnetic plates each oriented to provide a slot parallel to the plane of the loop formed by an expanding arc. In a second embodiment, the U-shaped plates each comprise a plurality of coplanar interleaved magnetic plates electrically insulated therebetween and having extending members to form pins lining the sides of the slot formed by the stack of plates. Additional independent pins inserted into the slots of an arc chute are also provided. A third embodiment includes fixed and movable contact arms and conductive means attached thereto to provide current flow in opposite directions through the contact arms. The contact arms and conductive means are positioned and sized so as to provide positive arc positioning.