Showing papers on "Fault current limiter published in 1984"

Fault protection system for power supplies that use ferro-resonant transformers

Abstract: A fault detection system for use in power supply systems using ferro-resonant transformers is presented. Current sensing means are used to sense the current flowing in the ferro-resonant circuit associated with operation of the ferro-resonant transformer. A fault detection circuit, powered by its own power supply connected to the primary source of power, monitors the sensed current and signals any significant change therein. A fault condition in any of the secondary circuits of the transformer causes the ferro-resonant current to change, and upon sensing this change, the fault detection circuit disconnects the primary of the transformer from the source of power.

Process and device for determining a parameter associated with a faulty electric conductor, using a composite monitoring signal

Abstract: Method and apparatus for determining, at a measurement point in a faulty conductor of electrical energy, a fault parameter such as the distance between the point of measurement and such fault or the direction of such fault. As a signal of a fault current, the device utilizes a signal I pa formed by a linear combination of a signal representative of homopolar current and a signal representative of an inverse current associated with a fault. The invention is particularly applicable in the case of networks having at the point of measurement an insensitivity to homopolar current or to inverse current.

Automatic kinescope beam current limiter

Abstract: In a television receiver, an automatic kinescope beam current limiter circuit includes a current path between a beam current sense point and an interating capacitor across which a control voltage is developed. A threshold conduction device causes the current path to exhibit different impedance characteristics and associated response times so that the limiter circuit has the ability to respond to average beam current values, as well as to above average r.m.s. beam current values such as may be associated with peak beam current conditions.

Performance of a Fault-Current Limiter with a New Type of Direct-Cooled Tubular Element

Abstract: As one component of a fault-current limiter a high-speed acting type of high capacity current limiting fuse has been developed by using a direct forced cooling of the fusible tubular element. Although several coolants such as air, water, liquid nitrogen etc. were tested, water was recommended to be the best coolant. This kind of current limiter is available as not only an AC interrupter, but also a high-voltage DC interrupter for protection of thyristors in AC/DC substations and so on. The fault- current limiter consisting of multi-stage fuses could interrupt a prospective current of 7kA under a voltage of DC 40kV in l9ms after a fault occurrence.

Semiconductor fault-current limiters. Part 2: Investigations on a semiconductor-diode fault-current limiter for use in power systems

Abstract: Semiconductor-diode fault-current limiters, suitable for limiting subtransient and transient currents in an alternator system during symmetrical and unsymmetrical faults, are investigated. Experimental results covering the time response of line currents, diode current and current through the limiting inductor, as well as voltages across the diode and limiting inductor, are presented. In the laboratory experimental setup a microprocessor-based controller was made use of for fault initiation. Results of computer-aided analysis of a specific case of fault are discussed.

Semiconductor fault-current limiters. Part 3: Investigations on microprocessor-based thyristor fault-current limiter for use in power systems

Abstract: The feasibility of using thyristor fault-current limiters to limit transient and steady-state currents in an alternator during a symmetrical fault has been investigated. Experimental results include discussions on time reponse of line currents, current through one of the thyristors and limiting inductor as well as voltage across the thyristor and limiting inductor. Triggering of the thyristor elements has been implemented through a microprocessor-based controller. The fault analysis with the aid of a computer is also included for a specific case.