Abstract: An electric fuse is of the type including indicating means for indicating if the main fusible element has melted. The indicating means includes a first and second auxiliary fusible element, each having a higher resistance than the main fusible element. When the fuse is fully assembled, and the main fusible element has melted, the path of current is through the first and second auxiliary fusible elements. The second auxiliary fusible element functions to restrain movement of an indicator button. When current flows through the auxiliary fusible elements, the second auxiliary fusible element is designed to melt first, thereby causing the indicator button to move. The operability of the first and second auxiliary fusible elements can be independently and non-destructively determined before and after assembly of the fuse. After fuse assembly, the fuse can be non-destructively disassembled so as to determine the operability of the first and second auxiliary elements.

Abstract: A dc measuring circuit for power rectifiers is described wherein primary line current is utilized to measure direct current output. In the measuring circuit, line current transformers are connected to a multiphase instrument rectifier through a phase shifting current transformer which is adjustable to compensate for differences between the primary and secondary line current phase shift characteristics of the power transformer and any phase shift in the line current transformer. By such compensation, the average value of rectified primary line current in the measuring circuit is maintained independent of the commutating angle of the rectified power current. The dc measuring circuit includes means for providing unity current transformation through the phase shifting current transformer. The dc measuring circuit also includes means for handling the presence of zero sequence current without causing measurement error or circuit damage.

Abstract: A dry well fuseholder for use with electrical apparatus containing a dielectric liquid. The holder has an outer, liquid-tight, tubular shell and a number of components inside the shell abutting coaxially in the following order: an annular fitting adapted for supporting the fuseholder on the apparatus; an insulating tube; an annular fuse terminal; another insulating tube; and an annular fuse terminal closed at one end. Glass fibers bonded together with epoxy resin are wound over the peripheral surface of the fitting-tube assembly to produce the shell. Seals are located between the fittings and shell near the joints of fittings and tubes. These seals are composed of a material which swells on contact with the dielectric liquid. This is a division, of application Ser. No. 680,209, filed Apr. 26, 1976, now U.S. Pat. No. 4,081,778.

Abstract: A voltage regulating system for an AC electrical power system includes a reactive converter having fixed capacitors and fixed inductors. Static switching devices are provided and include gating circuits for controlling the conduction angle of the switching devices so as to control the magnitude of the reactive current traversing the fixed inductors. RMS transducer circuitry is provided for generating an electrical signal representative of the RMS value of the voltage waveform at a critical point in the AC power system at which good voltage regulation is desired. Circuitry is provided for generating an electrical signal representative of a desired RMS value. Comparison components are provided for comparing these two electrical signals and generating an output signal for use in controlling the conduction angle of the switching devices so as to regulate the magnitude of the voltage waveform at the critical point in the AC power system.

Abstract: In an alternating current electric power system of the type subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of static switches in accordance with the magnitude of reactive load current. The compensation control includes means rapidly responsive to rapid current disturbances. In one embodiment, the compensation control includes devices for continuously sensing the phase and magnitude of the reactive load current. In another embodiment, the compensation control includes devices for sensing the phase and magnitude of the reactive load current 12 times per cycle of source frequency.

Abstract: An electromagnet for use in an extremely inverse time overcurrent relay, wherein extremely inverse relay performance is obtained as a result of the electromagnet's simplified design. The electromagnet comprises a core having two E shaped portions of unequal size, each portion including a base wall, two outer legs and an inner leg, with the inner legs of the two portions being arranged in aligned opposition. The opposed and aligned inner legs of the core constitute magnetic pole members having opposed faces spaced apart and defining an air gap therebetween. Each pole member is provided with a shading ring shading the pole member by greater than 50%. Further, the electromagnet is provided with a single energizing means located on the core for establishing a flux distribution in the air gap whereby a rotatable armature which may be located in the air gap may be driven in response to an energizing current.

Abstract: A solid state, reverse power flow detector and control circuit which samples the line voltage and current, once each cycle. The voltage sampling circuit includes a pulse generator providing a voltage pulse of short duration at a given time or phase angle in each cycle. The voltage signals are applied to an SCR through a gate operated by the current signals. With forward or no current the voltage signals do not reach the SCR. When current reverses the voltage signals are allowed to trigger the SCR. The SCR turns on a transistor energizing a relay, after a brief delay. The relay acts to set the regulator or other device in power reverse condition. When current again is forward the relay is deenergized and the device returned to the power forward condition.

Abstract: In an alternating current electric power system of the type subject to rapid load voltage regulation as a result of variations in reactive load current, reactive load current compensation is provided by fixed capacitors and inductors in parallel with the load, the inductors being in series with static switches which are phase controlled to continuously maintain the net reactive compensating current substantially equal and opposite to the reactive component of load current. Compensation control determines firing time of the static switches in accordance with the magnitude of reactive load current. Regulating means additionally controls firing time to maintain line current and line to neutral voltage at a selected line location substantially in phase coincidence. The regulating means is provided with means for enhancing the stability of the system under no load or light load conditions.

Abstract: A connector module for loadbreak operation having an insulating housing and a switch insert. The insert includes a container with a major portion of uniform diameter and a configuration such that the diameter does not increase from its outer end to its inner end, to permit the insert to be installed in the finished housing. Inside the container is a snuffer-contact assembly which has a bore lined with an ablative material. A bore contact having a gas port is attached to a snuffer tube of the assembly and has fixed to it a piston adapter for driving the snuffer-contact assembly toward the open end of the container tube in response to gas generated by arcing inside the bore. Resilient sliding contact means are fixed to the piston and press against the inside wall of the container tube to establish continuous electrical contact with it even while the piston is moving.

Abstract: A method for stripping bonded insulation from a rectangular wire. The wire is inserted into a wire-stripping mechanism through a pair of gripping jaws. On actuation of the mechanism the jaws are triggered to grip the wire. At least one knife is moved orthogonally to the wire surface to engage and penetrate the wire to be stripped. Then the knife is moved longitudinally along the length of the wire to strip insulation and a thin chip or sliver of metal from the wire. On the return stroke, the jaws are opened to release the stripped wire.

Abstract: An HVDC electric power delivery system having a floating current order current control subsystem is described. The system is comprised by power converters at each end of an HVDC power conductor link each of which includes a plurality of controllable electric valves connected between alternating current and the direct current electric power conductors together with means for cyclically firing the valves in a predetermined sequence and at firing angles measured with respect to the alternating voltage that can be varied to control the flow of power between the alternating current system and the direct current system. Each of the power converters further includes a regulator for comparing a plurality of input control signals which respectively represent different predetermined operating characteristics of the HVDC system during operation and for deriving an output error control signal that controls the firing angles of the valves.

Abstract: A semiconductor rectifier assembly comprises first and second electroconductive posts having portions between which a semiconductor body is sandwiched under pressure. A sealed housing for the semiconductor body comprises said posts, a hollow cylindrical insulator surrounding said semiconductor body and said post portions, and sealing means at opposite ends of the insulator for respectively forming seals between said posts and the ends of the insulator. The sealing means at one end of the insulator comprises a pair of annular metal flanges joined together at their outer peripheries. One flange is bonded adjacent its inner periphery to the insulator and the other is bonded adjacent its inner periphery to the adjacent post. A thin annular disc of electrical insulating material has a first portion adjacent its outer periphery disposed between said flanges and a second portion located radially inwardly of the first portion extending between the inner periphery of the insulator and the adjacent post.

Abstract: This vacuum-type circuit breaker has means for substantially reducing the tendency of the contacts to bounce apart in response to the impact between the contacts occurring at the end of a closing stroke. The circuit breaker includes a contact-wipe mechanism comprising a driving part and a wipe spring located between the driving part and the movable contact which spring is loaded to produce added closing force on the movable contact by continuing closing motion of the driving part after the contacts initially engage at the end of the closing stroke. The wipe mechanism further includes a bounce-suppressing spring acting in opposition to the wipe spring and discharging to aid said continuing closing motion of said driving part during the initial stages of said continuing motion following initial contact-engagement.The wipe mechanism also includes means for precisely controlling the forces imposed on the movable contact by acceleration at the start and termination of a contact-opening stroke.

Abstract: The specification discloses a power thyristor of the P-gate type wherein the outer cathode layer of N type conductivity overlies the P layer in the gate region. A gate pad is formed as a metallic coating over the N layer in the gate region with direct metallic connection through or around the underlying N layer and into the P type gating layer thereunder.

Abstract: This loss-of-vacuum detecting means for a vacuum circuit breaker utilizes input information derived from the current transformers of the overcurrent-sensing means typically present in medium voltage switchgear. In this overcurrent-sensing means, the current transformer secondaries for the respective phases of the switchgear are connected in parallel with each other across a shorting conductor; and in series with each secondary is the operating coil of an overcurrent relay. Connected in the shorting conductor is an "a" switch that is closed when the vacuum circuit breaker is closed and is opened when the circuit breaker is opened. Rectifying means is connected across said switch for developing a d.c. voltage when said switch is opened and one or more of said secondary windings is energized. Time-delay relay means is arranged to be energized by said d.c. voltage and is operable when the voltage thereacross exceeds a predetermined level for a predetermined minimum period following opening of said switch.

Abstract: The protective relay circuits herein provide a combined distance and overcurrent type of function. The protective relay circuit includes an a-c level detector or bi-polar threshold circuit to which the quantity I (Z.sub.R - Z.sub.F) is applied. The quantity I is the current in the line, Z.sub.R is a replica or reference impedance corresponding to the lines being protected and Z.sub.F is the line impedance to the fault from the relay measuring point. IZ.sub.F is equal to V, the voltage input to the relay. An output is provided from the a-c level detector only when the quantity I (Z.sub.R - Z.sub.F) exceeds a predetermined value. The output of the level detector is compared in a coincidence circuit, or AND gate, with a polarizing signal. The detection of coincidence for a selectable predetermined time period, as measured by a characteristic timer, results in an output signal for use in controlling operation of the trip coil of the circuit breaker.

Abstract: A magnetic amplifier having a magnetic core in the shape of a hollow cylinder is provided with a gate winding comprising series-connected coaxial conductors passing through the center of the hollow core.

Abstract: A module of the type having an elongated insulating housing, a contact-receiving bore in the housing, and a bore contact mounted in the housing in communication with the inner end of the bore, for receiving a rod contact of a matching module, is provided with an improved gas-trap valve which comprises a sliding segment gate. The valve is mounted adjacent the outermost end of the bore. It comprises an annular valve casing member having a central opening in alignment with the bore and a chamber in the casing in which the gate segments slide between a pair of parallel and opposed walls in a plane perpendicular to the bore and are biased in a closed position. A depression in the outer faces of the valve segments permits the valve segments to be forced into the open position in response to pressure by a rod contact inserted into the opening.

Abstract: This protective relay circuit responds to interphase faults on a three-phase power line by causing a circuit breaker connected in the power line to be tripped three-pole in response to interphase faults, but does not respond to a single line to ground fault, allowing a single pole to be tripped for this latter type of fault.

Abstract: This high-speed differential protective arrangement discriminates between a fault occurring in a differentially-protected zone of a power circuit and operation of a lightning arrestor connected to the power circuit in said zone. The protective arrangement comprises a relay which operates in response to such a fault but which remains inactive despite operation of the lightning arrestor. Despite this insensitivity to lightning-arrestor operations, the relay is still able to operate relatively fast at levels of fault-produced voltage across input terminals to the protective arrangement much lower than those developed across these terminals by lightning-arrestor follow-through current.