Power Fault Research Articles

Switching of Extra-High-Voltage Circuits III-Design of Air Blast Circuit Breakers

A line of outdoor air blast circuit breakers is described for ratings through 700 kv. These breakers are of a modular or building-block design and are an extension of an existing 115-345-ky line. They include resistors for preinsertion during circuit closing to minimize switching surges and are designed to handle the high charging current values of line dropping and the high recovery rates expected during power faults on transmission lines of extra-high-voltage (EHV) high capacity systems. The technical problems of EHV transmission impose numerous design criteria on power circuit breakers for these systems and do not permit the simple extrapolation of requirements from breaker designs of lower transmission voltages. Breaker development has paralleled the development of a new compound circuit test facility capable of proving its EHV high capacity abi1ity.

Effects of primary power contacts on aerial communication plant

During 1960 a co-operative test program was conducted to study the effects of power contacts on communication plants consisting of multiple wire, open wire, cable, and associated protectors and wiring. This information is required to engineer safe joint use of higher capacity power systems and some of the newer communication facilities. The characteristics of power and communication plant under certain power fault conditions have been determined.

A Line of 115-Kv through 460-Kv Air-Blast Circuit Breakers

Part I discusses a line of outdoor air-blast circuit breakers which has been developed for ratings of 115 kv through 460 kv. The breakers are of modular, or building-block, design, which allows the user to stock fewer spare parts and substantially reduces the personnel training problem. The breakers are expected to reduce the outage time of high capacity circuits for maintenance and inspection. They are rated to handle the high recovery rates encountered during power faults on transmission lines of high capacity systems. Part II discusses the utilization of a new design of gas-insulated current transformer by the air-blast breakers. Design details facilitate obtaining satisfactory protective relaying with current transformers on only one side of the interrupter contacts with a resulting substantial reduction in cost.

The Linascope Transmission Line Fault Locator

A pulse-type echo ranging fault locator has been developed which is suitable for locating sustained faults on telephone and power transmission lines. A number of these instruments have been in service for several years. They have been used to locate a wide variety of power and telephone line faults with significant reductions in service interruptions and economies in line patrolling. Before a new circuit is energized it may be tested with the linascope to ensure that all construction grounds have been removed and that all transpositions are correct. Telephone circuits also may be tested to locate sources of mismatch which introduce transmission losses. An automatic fault locator has been developed, which operates on the same principle and which automatically records the locations of sustained or transient power line faults.