Abstract: A differential protective relay system includes protective relays 19A and 19B at the terminals of a protected transmission line segment 21. Analog signals QL1 and QL2 are sampled at the respective ends of the protected line segment 21, digitally encoded using delta modulation and biphase-mark encoding, multiplexed and transmitted over a 1.544 Mbps T1 communication channel 20 to the other end of the line where they are decoded and compared with the local signal at that end. Power is removed from the protected line segment if the difference between the local and remote signals exceeds a predefined value. Biphase-mark encoding is employed so that a clock signal may be recovered from the decoded signals.

Abstract: A method for measuring an unknown voltage (V.sub.IN) using a voltage divider network in such a way that uncertainties in the values of the resistances do not affect the measurement. The unknown voltage is divided into three fractional voltages, the fractional voltages are measured, and the unknown voltage is computed on the basis of the fractional voltages. The unknown voltage is divided with a voltage divider comprising first, second and third resistors, and a first voltage (V.sub.o1) is measured across the first resistor, a second voltage (V.sub.o2) is measured across the second resistor and a third voltage (V.sub.o3) is measured across the third resistor. The unknown voltage V.sub.IN is computed in accordance with the equations disclosed in the specification.

Abstract: As the dielectric constant and the halfwave voltage of electro-optic crystals having a fourfold axis of rotary inversion are oppositely dependent on the absolute temperature, but their product is nearly independent of temperature, temperature compensation in an ac voltage measuring system utilizing such an electro-optic crystal is provided by measuring the time averaged current through the crystal. Good electric isolation is achieved by a current sensing circuit which produces a pulsed light signal having a pulse rate proportional to the time averaged current through the crystal. The pulsed light signal is converted to an electrical signal for input to a digital computer which calculates therefrom, and from a reference current and voltage measured at a reference temperature, and a time averaged voltage measurement, a temperature correction factor which is applied to the crystal halfwave voltage used by the computer in calculating the instantaneous value of the voltage to be measured.

Abstract: A modular closing resistor assembly can be added in line with the interrupter assemblies of an extra high voltage circuit breaker and has a relatively short length. The resistor element consists of two stacks of disks which are disposed side by side and are electrically connected such that the alternate disks of each stack are connected in series with one another. The operating mechanism of the unit includes a linearly moving roller which engages a crank arm which is in turn pivotally connected to operate the movable closing resistor contact with a motion and with a variable mechanical advantage adapted to cause the resistor contacts to close at high speed just after the interrupter contacts close and to open after the interrupter contacts open.

Abstract: A cradle or sling of banding strap material supports a wound magnetic core from an upper fixed support to at least partly relieve the weight of the core on the transformer winding and to permit the core to assume a more relaxed shape to reduce its internal stress and thus AW and TW core losses.

Abstract: A transformer having an integral cabinet with an apparatus for hinging and clamping the cover of the cabinet onto its base is provided. The hinge is formed by an L-shaped member extending from a lip surrounding a planar top formed in the cover. A flange having rearward and downward extending portions extends from the rear wall of the cabinet base. The hinge engages a slot formed in the downward extending portion of the flange. The distance from the hinge to the cover top is less than the distance from the slot to the upper edge of the rear wall on which the cover top rests. Thus, rotation of the cover into the closed position with the hinge engaged causes elastic deformation of the hinge, thereby creating a spring force which clamps the cover onto the base. Elastic deformation in the flange imparts addition clamping force. Sufficient clearance is provided for this elastic deformation by either sloping the rearward extending portion of the flange or sloping the planar top of the cover.

Abstract: A system and device are disclosed for protecting the primary windings of a distribution transformer from surge current which exceed a predetermined level including a tank for accommodating the distribution transformer, a first expanding arc gap extending between a first terminal and a second terminal on the secondary side of the distribution transformer, and a second expanding arc gap extending between a third terminal and the second terminal on the secondary side of the distribution transformer. The arc gap being mounted within the gas space of the tank which accommodates the distribution transformer such that a surge current which exceeds the predetermined level is directed through the arc gaps and dissipated by the expanding arc gaps thereby bypassing the secondary windings in order to protect the primary windings of the distribution transformer. The internally mounted arc gaps being effective when applied to either interlaced or non-interlaced distribution transformers.

Abstract: A method and apparatus for metering electrical energy with a meter having a base of a given configuration is shown to include a data member, attached to the base, for providing a data signal, at least a portion of which is representative of the base configuration, and a processor, connected to the data member, for comparing the meter base configuration to a reference configuration and for providing an indication signal whenever the meter base configuration and the reference configuration do not match. If the data member generates a serial data signal of digital words, it is desireable for a number of bits in each serial communication to be representative of the meter base configuration. Such a serial data signal is achieved if an input/output expander having a plurality of inputs is utilized. In such an embodiment, it is preferred to provide digital signals representative of the meter base configuration to select inputs of the expander.

Abstract: A microprocessor based tie relay controls a tie circuit breaker between a main bus and a transfer bus to which any one of a number of feeder lines may be connected through a disconnect switch when the feeder circuit breaker associated with that feeder line is out of service. Settings for the protection characteristics of each of the feeder relays controlling the feeder circuit breakers are stored in non-volatile memory together with a default protection characteristic suitable for protecting any of the feeder lines. The appropriate protection characteristic for the feeder line connected to the transfer bus is selected for use by the tie relay in controlling the tie circuit breaker. This selection may be made manually by an operator, or preferably automatically by the microprocessor of the tie relay which monitors the states of the feeder circuit breakers and of the disconnect switches and selects the settings associated with the feeder line whose feeder circuit breaker is open and disconnect switch is closed.

Abstract: A system and device are disclosed for protecting the primary windings of a distribution transformer from surge current which exceed a predetermined level including a tank for accommodating the distribution transformer, a first arc gap extending between a first terminal and a second terminal on the secondary side of the distribution transformer, and a second arc gap extending between a third terminal and the second terminal on the secondary side of the distribution transformer. The arc gap being mounted within the gas space of the tank which accommodates the distribution transformer such that a surge current which exceeds the predetermined level is directed through the arc gaps and bypasses the secondary windings in order to protect the primary windings of the distribution transformer. The internally mounted arc gaps being effective when applied to either interlaced or non-interlaced distribution transformers.

Abstract: An apparatus and method are provided for drilling thin-walled glass articles. The apparatus is comprised of a drilling machine having upper and lower triangulated arm assemblies to which opposing drills are attached. The arm assemblies pivot about a common shaft. The shaft is supported by a support assembly attached to a sliding table. First and second actuators mounted on the support assembly urge the arm assemblies to pivot about the shaft, thereby controlling the feed rate and stroke of the drills. In a second embodiment adapted to drill deep glass articles, the lower arm assembly has an intermediate frame which pivots about an upper shaft along with the upper arm assembly. The lower arm assembly also has a lower arm which pivots about a lower shaft under the urging of a third actuator, allowing the drill spindle attached to the lower arm to enter and withdraw from the deep article without scratching the sides of the article.

Abstract: A steel sheet (10) having a stress-relief annealed, structure with a plurality of magnetic domains (12) is made by drilling a plurality of closely spaced, small holes (15) through the entire thickness of the steel sheet, where the drilling is effective to form additional domain walls (17) and subdivide the magnetic domains.

Abstract: Disclosed is a method of making a repairable transformer having an amorphous metal core. The three uncut legs of an annealed wound amorphous metal core are covered with an adhesive material while leaving the cut leg and both adjoining radii covered, but not bonded. The core joint is opened and coils are placed over the legs that adjoin the cut leg. The core joint is closed and the edges of the joint and both adjoining radii are covered with an inner layer of porous material which is secured by an outer wrap of electrical grade steel. The resulting transformer can be easily repaired by unwrapping away the porous material that covers the cut leg and the adjoining radii, opening the core joint, replacing a defective coil or core, reclosing the core joint, and rewrapping the porous material and reclosing the outer layer of electrical grade steel.

Abstract: An electrical transformer having an integral cabinet with an apparatus for latching and locking the doors of the cabinet. The apparatus is comprised of a three point latch system. The first and second latch points are vertical latch rods which engage sills in the cabinet. The third latch point is a latch plate which rotates with a shaft extending through the first door and to which a handle is attached. In the secured position, the latch plate rotates behind a flange extending from an interior wall, thereby preventing the door from being pulled open. The internal wall divides the cabinet into low and high voltage compartments and forms a structural portion of the cabinet. A bolt extends through the first door, the second door, the latch plate and the flange, thereby preventing the doors from being pulled open and preventing rotation of the handle. A cylinder attached to the first door surrounds the head of the bolt and prevents access thereto.

Abstract: A steel sheet (10) having a stress-relief annealed, structure with a plurality of magnetic domains (12) is made by drilling a plurality of closely spaced, small holes (15) through the entire thickness of the steel sheet, where the drilling is effective to form additional domain walls (17) and subdivide the magnetic domains.

Abstract: A voltage measuring system utilizes an electro-optic voltage transducer (EOVT) in which two beams of polarized light injected into one end of an electro-optic crystal parallel to its fourfold axis of rotary inversion are reflected back through the crystal by a prism so that the optical inputs and outputs, including polarizers, collimators, optic fibers, and fractional wave plates where required, are all located at one end of the crystal, which is preferably connected to the low side of the voltage to be measured. The EOVT is supported substantially only at the end with the optical inputs and outputs, with the free end on which the prism is mounted being substantially unsupported. In one embodiment of the invention, a triangular prism is used to reflect the polarized light back through the prism, in another a pyramid prism is utilized.

Abstract: A method and apparatus for rapidly analyzing ac waveforms containing dc offset by generating digitized samples of the waveform to be analyzed with alternate samples separated by ninety electrical degrees. Alternate samples are paired for calculation of the magnitude and phase of the waveform. A suitable microcomputer performs a calculation using pairs of the most recently generated samples. Using the pairs of samples, the microcomputer calculates the dc offset, and the peak magnitude of the waveform which may be voltage or current. The phase angle of the waveform can also be calculated if required. The method and apparatus are particularly useful with protective systems where the calculation is necessary to determine whether there is a fault on an electric power transmission line. In addition, the effects of dc offset are eliminated and thereby false trips are avoided. A reliable system having a fast response time at relatively modest cost is provided.

Abstract: A system for transmitting data via a telephone line by means of a data communications device (4) connected to the telephone line, at least one other communications device being connected to the telephone line and each device being switchable between an inactive state, in which the device is not in use and presents a high impedance to the telephone line, and an active state, in which the device reduces the telephone line voltage and signals can be transferred between the device and the telephone line, the system including a telephone line state detection unit (10) associated with the data communications device (4) and connected to the telephone line for electrically monitoring the telephone line to provide an indication of the state of another communications device connected to the telephone line.

Abstract: A microcomputer repetitively samples a signal representative of the instantaneous state of an electrical contact and initiates a count in response to the first sample which indicates a contact state different from a stored status of the contact. The microprocessor counts up for samples indicating an active state of the contact and down for inactive samples. If the count increases to a predetermined count representing a certain net count of active samples when the stored status is inactive, the stored status is changed to active. Similarly, the stored status is changed from active to inactive if the count decreases to a predetermined count representing a certain net count of inactive samples. The time of the first sample which indicates a contact state different from the stored status of the contact is stored as a temporary time. If the stored contact status is changed, the stored temporary time is saved as the valid time of the change in status.

Abstract: Events at spaced locations, such as contact activity in the protective relays of an electric power distribution network, are time stamped using a single remote clock by a system which includes one or more slave stations monitoring the events. Each slave station initiates a count of locally generated clocking pulses of fixed duration upon detection of the first event monitored by it. Identification of the first event is stored in a first slot in memory. Additional memory slots each store the identification of a subsequent event and the count at the occurrence of that subsequent event. Upon command from a remote master station, the current count is stored in the first slot and the contents of the first slot and of the additional slots are transmitted over a communications network to the master station.