Oil Circuit Breakers Research Articles

Lightning Strength of Wood in Power Transmission Structures

ALTHOUGH wood has been known to possess the excellent properties of mechanical strength in combination with insulation strength almost since the beginning of the electrical art, its real lightning strength was not generally appreciated until within comparatively recent years. It is true that it was rather extensively used in the past to supply power frequency insulation in treated form alone or with transil oil. For example, wood either solid or laminated has been employed for years in operating rods on oil circuit breakers and in terminal and spacing blocks in transformers. The 60-cycle strength of wood under those conditions has been studied, and although the results were not made available generally, the strength factors had been known with considerable preciseness for some time. In these applications, however, the 60-cycle (i.e., power frequency) strength of wood has been of paramount interest, and the lightning or impulse insulation value of secondary interest, either because the latter was considered comparatively unimportant or because the impulse strength furnished by other insulating members or mediums in the structure was considered sufficient.

The ultrahigh-speed reclosing expulsion oil circuit breaker

The ultrahigh-speed reclosing expulsion oil circuit breaker

The Ultrahigh-Speed Reclosing Expulsion Oil Circuit Breaker

Discussion and author's closure of a paper by A. C. Schwager published in the August 1937 issue, pages 968–70, and presented For oral discussion at the development of protective equipment session of the Pacific Coast convention, Spokane, Wash., August 31,1937.

The ultrahigh-speed reclosing expulsion oil circuit breaker

Discussion and author's closure of a paper by A. C. Schwager published in the August 1937 issue, pages 968–70, and presented For oral discussion at the development of protective equipment session of the Pacific Coast convention, Spokane, Wash., August 31,1937.

System recovery voltage determination by analytical and A-C calculating board methods

THE PERFORMANCE of current interrupting devices on systems is dependent not only on the characteristics of the device itself but also on the characteristics of the system. The voltage rating of the system and the connections at the time of fault have considerable influence on the recovery voltage and in turn on the application of the interrupting device. For example, the last oil circuit breaker to open must be capable of interrupting current under extreme system recovery conditions, while a deion protector tube always has at least the line section on which it is applied, connected at the time of clearing. This means that in considering broadly the current interruption problem it is necessary to have a knowledge of voltage recovery characteristics for a large number of system conditions. Tests can be made for particular system conditions, but this is expensive and it is difficult to obtain data for all possible combinations of faults and system connections. A general analysis taking into account all the factors makes calculations practically impossible, and on account of the complexity, the human factor cannot be overlooked.

Further contribution to the discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear”

Further contribution to the discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear”

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the North-Eastern Centre, at Newcastle, 24th February, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the North-Eastern Centre, at Newcastle, 24th February, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the Institution, 20th February, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the Institution, 20th February, 1936

The authors' reply to the discussions on “The development of the single-break oil circuit-breaker for metalclad switchgear” at London, Newcastle, Manchester and Birmingham

The authors' reply to the discussions on “The development of the single-break oil circuit-breaker for metalclad switchgear” at London, Newcastle, Manchester and Birmingham

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the South Midland Centre, at Birmingham, 9th March, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the South Midland Centre, at Birmingham, 9th March, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the North-Western Centre, at Manchester, 25th February, 1936

Discussion on “The development of the single-break oil circuit-breaker for metalclad switchgear” before the North-Western Centre, at Manchester, 25th February, 1936

The development of the single-break oil circuit-breaker for metalclad switchgear

The theoretical considerations in the choice of number of breaks are analysed and it is shown that, while for plain breakers multi-break construction may have its advantages, the more efficient the arc-control devices employed the less the advantages of additional breaks become with normal designs. In particular, it is shown that for a metalclad and cable system, the duty on one break of a multi-break controlled- arc breaker is almost as great as for that of a singlebreak unit. Experimental evidence in support of the theory advanced, obtained with cathode-ray equipment, is given.The development of a single-break 66-kV metalclad equipment is described, with particular reference to the interrupting ability, and test-results are given, obtained on four different short-circuit plants, showing consistent operation. The advantages to the user of the single-break oil circuit-breaker are shown by comparison with double-break designs of similar rating, and single-break layouts are described for different switching schemes and system voltages.In the Appendix an analysis is made of 3-phase cathode-ray films, showing that no leakage current is carried and that in consequence the observed reliable operation is to be expected.

Special tests on impulse circuit breakers

A novel circuit arrangement that supplies a large current to a circuit breaker under test and then subjects the open terminals to a high recovery voltage has been used in testing the 2,500,000-kva 287.5-kv impulse oil circuit breakers built for the Boulder Dam-Los Angeles transmission line. A description of this arrangement, which makes available several times the apparent power of the testing apparatus, is given in this paper, together with oscillograms which show details of the arc extinction process not previously known, and the results of a study of voltage distribution.

Special Tests on Impulse Circuit Breakers

A novel circuit arrangement that supplies a large current to a circuit breaker under test and then subjects the open terminals to a high recovery voltage has been used in testing the 2,500,000-kva 287.5-kv impulse oil circuit breakers built for the Boulder Dam-Los Angeles transmission line. A description of this arrangement, which makes available several times the apparent power of the testing apparatus, is given in this paper, together with oscillograms which show details of the arc extinction process not previously known, and the results of a study of voltage distribution.

Oil circuit breaker and voltage recovery tests

Oil circuit breaker and voltage recovery tests

Oil circuit breaker and voltage recovery tests

Oil circuit breaker and voltage recovery tests

Analysis of the Failures of Oil Circuit Breakers

Analysis of the Failures of Oil Circuit Breakers

Steel-Cylinder Grid-Controlled Mercury-Arc Rectifiers in Radio Service

This article describes a steel-cylinder grid-controlled mercury-arc rectifier as applied to radio transmitting service. The various parts of the rectifier cylinder are pointed out with reference to a picture of the rectifier unit. The use of mercury seals is described, and the operation of various auxiliaries such as vacuum pumps, vacuum meter, and ignition-excitation equipment is dealt with. Particular reference is made to the use of grid control for deionizing the anodes after carrying current, regulation of the direct-current output voltage, ultra-high speed electronic circuit breaker protection of the rectifier and radio transmitter equipment, and inversion of electrical energy stored in the filter system during the interruption of short circuits. The operation of the grid-control protective circuit as compared to that of an alternating-current oil circuit breaker in interrupting direct short circuits is illustrated by means of oscillograph records.

Oil circuit breaker and voltage recovery tests

Oil circuit breaker and voltage recovery tests

Oil Circuit Breaker and Voltage Recovery Tests

A series of tests on a circuit breaker of the oil blast type was conducted at the Richmond station of the Philadelphia Electric Company. Particular attention was given to the rate of recovery of voltage following the actual interruption of the circuit. Unusual details in the operation of the cathode ray oscillograph also were worked out. These, and other features of the test, are described in detail in this paper.