Abstract: An electrical grounding suppressor device, and the method of using the same, which is placed directly in line with the co-axial center conductor of cable television distribution lines without inhibiting or causing significant loss of the radio frequency signal in the co-ax line. An electronic circuit senses a transient surge on the co-ax line and triggers a rapid clamping action to ground to dissipate the harmful effects of the surge.

Abstract: A firing control scheme, including a method and apparatus, for secure vernier operation of a thyristor controlled series capacitor (TCSC) in series with a transmission line uses phase controlled firing based on monitored capacitor voltage and line current. The TCSC system has a thyristor switched inductive commutating circuit in parallel with the series capacitor. Vernier operation of the TCSC system is provided by predicting an upcoming firing angle for switching the commutating circuit to conduct a thyristor bypass current pulse therethrough. The current pulse causes an alternating offset component of voltage to appear across the series capacitor, in addition to the normal voltage component. Each current pulse changes the capacitor voltage proportionally to the integrated value of the current pulse.

Abstract: In a system for transmitting an electrical power supply by means of an over-head power transmission line supported by power transmission towers, a fault such as a short-circuit fault and a ground fault is detected by providing optical current sensors having opto-magnetic elements and opto-electric field elements on respective conductors of the transmission line to detect a fault current and fault voltage on the basis of the Faraday's effect and Pockel's effect. Light beams passing through the elements are modulated by the magnetic fields induced by the currents passing through the conductors and the voltages on the conductors, and thus include information about the current and voltage. There is further provided a circuit for calculating a distance to a fault point in accordance with the detected current, voltage and a phase difference therebetween and a known impedance of the power transmission line.

Abstract: A method for limiting short circuit current flow in a Field Effect Transistor (FET) to limit the power dissipated therein includes sensing a rise in the drain-to-source voltage of the transistor and clamping the gate-to-source voltage to a predetermined adjustable value thereby reducing the magnitude of the short circuit current flow to within the safe operating characteristics of the device. A comparator switch circuit is responsive to the drain-to-source voltage of the FET exceeding a reference voltage value for clamping the gate-to-source voltage to a predetermined reduced voltage. A trimmable resistive network is connected between the gate and the source electrode of the transistor for adjusting the gate to source clamped voltage potential to compensate for variations in transistor transconductances from one transistor to the next that they may be used in conjunction with the electronic circuitry.

Abstract: A method by which a turbine generator (1, 2, 3) can be protected against sub-synchronous frequencies occurring in an electric network which is connected to the turbine generator and which incorporates capacitors. The method is based on de-equalizing the subsynchronous natural frequencies of the three phases, so as to weaken the coherence of the frequencies. This is achieved by incorporating in each of two of the phases a respective inductance L of mutually different size and by changing the capacitance equivalently with a series capacitance C such as to fulfill the condition 1/LC=.omega..sub.o.sup.2, where .omega..sub.o is the network frequency.

Abstract: In a overhead power transmission system, a sensing member for detecting condition of the overhead power transmission or distribution lines or the ground wire is secured to an anchor and clamp member for anchoring and clamping the power line or overhead ground wire so as to prevent undesired movement of the sensing member.

Abstract: In order to protect a cable, which can be laid in the soil and the conductors of which are electrically conductively connected with a plurality of electrical circuit units, which are arranged distributed at spacings along the cable in the interior of the cable core (2), which is surrounded by a sheath, which comprises a layer of high electrical conductivity and an outer layer for protection against chemical influences, reliably against electrical and magnetic disturbances coming from outside, the sheath additionally displays an inner layer of a material of high magnetic permeability. Beyond that, the outer layer can possess an electrical conductivity, the value of which lies between the conductivity values of the surrounding soil and the middle layer. In order to be able to produce such a cable as simply as possible, the circuit units are first electrically conductively connected with the conductors and then embedded together with these in the inner protective layer of the cable, for example by extruding-in.

Abstract: A broken conductor guard system for a single neutral power distribution system in which at least one high voltage power conductor is suspended between power poles with a neutral conductor being similarly suspended between the poles vertically below the high voltage conductor includes a broken conductor guard comprising an elongated rod with hook-shaped ends clamped with a clamping mechanism to a single neutral conductor in a horizontal plane and transverse to the neutral conductor. Apparatus is coupled to the clamping mechanism for preventing rotation of the broken conductor guard about the neutral conductor so as to maintain the guard in the horizontal plane.

Abstract: A transmission line protection system arranged such that a leakage current detector is provided at an end of an insulating device such as an insulator connected at one end to a corresponding one of arms of a steel tower and connected at the other end to a transmission line of each phase, thereby detecting an arrester leakage current flowing in the transmission line of each phase, an output signal of the leakage current detector being led to a repeater through an optical fiber cable, an output of the repeater being transferred to a control/supervisory board in a substation through an optical fiber cable. In the control/supervisory board, preferably, a received digital signal which was converted from an analog signal at said leakage current detector is displayed on a cathode ray tube. In such an arrangement, it is possible to smoothly perform supervision of the status of the transmission lines without causing maloperations due to influences from the transmission lines.

Abstract: A broken conductor guard for use in an electrical power transmission system including at least one high potential power conductor positioned vertically above two neutral conductors. The broken conductor guard comprises a conductive rod electrically connected transverse to the neutral conductors. The rod extends a predetermined distance on each side of the two neutral conductors in a substantially horizontal plane such that a broken high-potential conductor will fall on the rod and be short-circuited to the neutral conductors.

Abstract: Device protecting a coaxial cable against high-powered low-frequency spurious pulses. A lightweight, compact device comprising a microstrip T-junction (5) folded back in the shape of an E on a substrate (6) integral to a single ground plate (7), with the branches of the E between the center point A and the coaxial plugs (1, 2) forming a quarter wavelength, as does the center horizontal branch of the E between points A and B. According to one of the variants, two microstrips arranged in parallel and separated by a dielectric substrate establish a quarter-wave trap. Application to microstrip resonant circuits.

Abstract: A switched four-legged reactor bank which operates in combination with line circuit breakers can be used to extinguish faults on untransposed transmission lines. It comprises three shunt reactors, a neutral reactor and three switches for performing high side reactor switching. The reactor bank also provides transmission line compensation.

Abstract: A computer based control system having a protection circuit including a bistable circuit arranged to disable the outputs of the control system at the end of a scan period of the system. The bistable circuit is operated through logic gates arranged to monitor fault in the control system.

Abstract: In an electric cable power transmission line of the class wherein three phase metal sheath single core power cable sections are interconnected by junction boxes, two sets of ordinary junction boxes at the opposite ends of each unit line section are grounded, two sets of junction boxes are provided in each unit line section, at each set of the insulating junction boxes the sheaths of the cables of one phase on one side of the insulating junction boxes are crossconnected by cross-connecting wires to the sheaths of the cables of another phase on the other side thereby forming three loop circuits each including the grounding connections of the ordinary junction boxes, the sheaths of the cable sections and the cross-connecting wires, saturable reactors are connected in series with only one or two of the loop circuits. This arrangement reduces the number of the saturable reactors and protective devices for corrosion preventing layers as well as the inductive interference to nearby communication lines.

Abstract: A ground wire monitoring circuit particularly adapted for use in connection with mining machinery that is supplied with alternating current through a flexible cable from a power source remote from the machine. The cable contains phase conductors, a ground wire and a pilot wire. The ground wire is energized through the pilot wire from a voltage derived from the alternating current power supply at the remote source. Any failure of the pilot wire or ground wire is detected by circuit means adjacent the remote power source and in the event of such failure the power circuit leading to the machine is immediately opened. The power circuit is opened in the event of failure of the ground wire even though there may be low resistance parallel ground paths between the machine frame and the remote power source.