Oil Circuit Breakers Research Articles

Abridgment of the fault ground bus: Its use and design in Brunot Island switch house of Duquesne light company

This paper describes the ground protection in the Brunot Island switch house of the Duquesne Light Company at Pittsburgh, Pa. This switch house constructed on the vertical isolated-phase plan, is divided structurally into several completely insulated sections. The well-known fault ground bus system of protection is applied and made effective by the special features of construction not heretofore used. Details of building construction and of fault ground bus application are given. Arrangements for heating, ventilating, and lighting the buildings are such as not to interfere with phase isolation and insulation. Oil circuit breaker mechanisms are insulated where necessary to maintain insulated sections in the building subdivision. The fault ground bus location, connections, and special details of construction are outlined. Preliminary tests, relay settings, and operating results are given.

The Fault Ground Bus Its Use and Design in Brunot Island Switch House of Duquesne Light Company

This paper describes the ground protection in the Brunot Island switch house of the Duquesne Light Company at Pittsburgh, Pa. This switch house constructed on the vertical isolated-phase plan, is divided structurally into several completely insulated sections. The well known fault ground bus system of protection is applied and made effective by the special features of construction not heretofore used. Details of building construction and of fault ground bus application are given. Arrangements for heating, ventilating, and lighting the buildings are such as not to interfere with phase isolation and insulation. Oil circuit breaker mechanisms are insulated where necessary to maintain the building subdivision into insulated sections. The fault ground bus location, connections, and special details of construction are outlined. Preliminary tests, relay settings, and operating results are given.

"Synchronized at the Load''-III System tests and operating connections

System test results, operating connections, and experience with the New York City system synchronized at the load are given. Data obtained by test are presented, showing the behavior of the system when generators are operated synchronized only through a low-voltage a-c. secondary network. The adaption of this method of connections to the New York City 60-cycle system, including system layout, station and feeder arrangement, and automatic recording apparatus is described. Experience with these connections has demonstrated that stable performance of prime movers is obtained, load and wattless control is simplified, oil circuit breaker duty is reduced, and voltage fluctuation at customer's service during system disturbances is materially decreased.

Abridgment of “synchronized at the load” — III: System tests and operating connections

System test results, operating connections, and experience with the New York City system synchronized at the load are given. Data obtained by test are presented, showing the behavior of the system when generators are operated synchronized only through a low-voltage a-c. secondary network. The adaptation of this method of connections to the New York City 60-cycle system, including system layout, station and feeder rearrangement, and automatic recording apparatus, is described. Experience with these connections has demonstrated that stable performance of prime movers is obtained, load and wattless control is simplified, oil circuit breaker duty is reduced, and voltage fluctuation at customer's service during system disturbances is materially decreased.

Automatic Reclosing of High-Voltage Circuits

The experience of the Alabama Power Company with the reclosing of high-voltage circuits is described, this covering numerous installations on 22-, 44-, and 110-kv. circuits. No definite reclosing cycles are recommended but instead this paper deals with various typical applications of high-voltage reclosing oil circuit breakers on the Alabama Power Company system.

An introduction to researches on circuit breaking

This paper is an introduction to the Electrical Research Association's researches on arc rupture which have been in progress since 1922.An introductory section describes the genesis and aims of the research. The problem of circuit breaking is far more complicated than has been generally supposed, and can be solved only by separate study of the numerous variables involved. The apparatus, controls, and general lay-out of the testing station at Carville are described.The investigators aimed at means for preventing the arc from re-striking, rather than attacking the arc when heavy current is flowing, which may cause heavy energy release.It is shown that, in oil switches, the arc is often broken while the contacts are still within the gas bubble, so that, in such cases, arc extinction is not due to the quenching effect of the oil. Experiments have proceeded along two lines: (1) Study of the gas formed and of its arc-rupturing properties as compared with other gases, with a view to its utilization to full advantage in arc rupture; and (2) a study of the best methods of utilizing the good features of oil for like purpose, the general aim being the utilization of each method separately or in combination in improved or new types of design.Novel methods of gas-sampling during arcing are described, and the results are given of gas collection and analysis covering a wide range of currents and powers.The present paper deals mainly with arcing in gas. For given gaseous conditions in the gap between the contacts at current pause, the adequacy of the gap depends on the instantaneous value of the voltage gradient appearing across it at current zero, and it is found that, for arcs in hydrogen, the. length of critical gap is approximately proportional to the sine of the angular displacement between current and “virtual” voltage zeros. This differs radically from Bauer's conclusions. In arcs in oil there are superimposed phenomena, but in general the same law applies.With asymmetrical currents in gas and oil there is a phase-displacement effect which affects the available voltage in addition to the phase angle due to circuit conditions.Experimental results on arc-voltage characteristics are given which indicate that Norberg's application of Steinmetz's formula, if used over the range considered in the present paper, would lead to large errors in the results obtained for arc energy, whereas his experimental results, though few in number, are consistent with the results here described.A formula for arc energy when arcing takes place in gas is developed, based on simplified assumptions arising from experiment and theory. This formula illustrates the great complexity, more especially of certain known features of the time and frequency factors, which may in certain circumstances play a highly important part in affecting arc length and energy production; these appear to have been omitted in the previously published formulæ of Bauer and others.The above work leads to certain practical applications.Certain effects of arc lengthening by mechanical and electromagnetic means are discussed. This section concludes with some description of the principles of operation of a new device for arc rupturing by gas blast, which has been developed as a direct outcome of the investigation of arcing in gas. Models tested show great improvement on recognized methods of arc rupture in oil, and show promise of a satisfactory solution of the problem of arc rupture in gas, which is the main subject of this introductory paper.In spite of the added experimental difficulties due to the presence of oil in oil circuit-breakers, great advance has been made and further details will be given when the patent situation permits.

Abridgment of the structural development of the Deion circuit breaker up to 15,000 volts

UP to the present time, the interruption of an a-c. circuit has been accomplished generally in one of two ways. The arc may be drawn between contacts located in some insulating liquid such as oil. In this case, the insulating value of the oil depreciates with each current interruption until it reaches a point where it must be renewed. On the other hand, the arc may be drawn in air with no means of extinguishing it other than lengthening it to such an extent that the generated voltage is no longer able to maintain it. For modern generating voltages, this requires arcs of great length and, for the upper range of transmission voltages, results in arc lengths which are impractical. As a result of this limitation, the oil circuit breaker has assumed a position of paramount importance on modern operating systems.

Abridgment of application of wound type current transformers installed in high-voltage oil circuit breaker tanks

Abridgment of application of wound type current transformers installed in high-voltage oil circuit breaker tanks

Abridgment of extinction of an A-C. arc

The transition from high conductivity to high resistivity which an a-c. arc undergoes on extinction is studied. Theory and approximate calculations are given for the rate of recovery of dielectric strength of the arc space for short arcs, and results are given of experiments on short arcs, and arcs in holes and slots in insulating material and insulating plates. The influence of chemical activity in arc gases is discussed. Factors contributing to the success of the a-c. oil circuit breaker are suggested.

Extinction of an A-C. Arc

The transition from high conductivity to high resistivity which an a-c. arc undergoes on extinction is studied. Theory and approximate calculations are given for the rate of recovery of dielectric strength of the arc space for short arcs, and results are given of experiments on short arcs, and arcs in holes and slots in insulating material and insulating plates. The influence of chemical activity in arc gases is discussed. Factors contributing to the success of the a-c. oil circuit breaker are suggested.

Abridgment of improvements in moderate capacity oil circuit breakers

The increased duty requirements of power station service require circuit-breaker design to give maximum interrupting capacity in a minimum of space. Compact, relatively high-power breakers, having all three poles in a single round tank, have been designed. In addition to increasing the rating for a stipulated space, these give improved performance over types previously available. The relations of the current-carrying loops inside the breaker and the diversity factor afforded by the common oil volume and air space give superior results in operation. This type of design permits use in current ranges where decreased arc energy, as compared to power handled, can be secured.

Operating Experience with High-Speed Oil Circuit Breakers

This paper outlines the experience of the New York, New Haven and Hartford Railroad with three high-speed oil circuit breakers which were installed in 1925 to serve an electrified branch line carrying freight and passenger traffic, both local and through. Satisfactory operation of paralleling commercial communication circuits, as well as of its own, presented an immediate problem, which after study outlined in the paper, finally yielded, and the answer, in part, was high-speed circuit breakers. The electrical and mechanical characteristics of these are set forth in detail and illustrated. A number of tests of the circuit breakers and communication circuits made by short-circuiting the 11,000-volt lines on the branch showed currents up to 3000 amperes, and openings in from one-half to one and one-half cycles, with satisfactory operation of commercial and railroad communication plant. A detailed record of the service operations of the circuit breakers along with a statement of failures is given. It is proper to say that the latter were more numerous in the early days of their use than they have been in recent months, and that a number of the faults are chargeable to the railroad's urgent need for the equipment, thereby considerably limiting the development and testing time desired by the manufacturer. While it was not discussed in detail in the paper it goes without saying that in the design and installation of the circuit breakers safety was a paramount consideration.

Application of Wound Type Current Transformers Installed in High-Voltage Oil Circuit Breaker Tanks

Wound type current transformers installed in the tanks of high-voltage oil circuit breakers have been in operation for many years. The experience gained during this period has resulted in fairly clear definitions as to the types of installations to which they are best suited, and to designs of transformers which are highly reliable. The purpose of this paper is to present a brief history of some of the developments leading up to the present application of wound type current transformers in circuit breakers and to indicate some of the conditions under which they offer special advantages.

Operating experience with high-speed oil circuit breakers

This paper outlines the experience of the New York, New Haven and Hartford Railroad with three high-speed oil circuit breakers which were installed in 1925 to serve an electrified branch line carrying freight and passenger traffic, both local and through. Satisfactory operation of paralleling commercial communication circuits, as well as of its own, presented an immediate problem, which after study outlined in the paper, finally yielded, and the answer, in part, was high-speed circuit breakers. The electrical and mechanical characteristics of these are set forth in detail and illustrated. A number of tests of the circuit breakers and communication circuits made by short-circuiting the 11,000-volt lines on the branch showed currents up to 3000 amperes, and openings in from one-half to one and one-half cycles, with satisfactory operation of commercial and railroad communication plant. A detailed record of the service operations of the circuit breakers along with a statement of failures is given. It is proper to say that the latter were more numerous in the early days of their use than they have been in recent months, and that a number of the faults are chargeable tot he railroad's urgent need for the equipment, thereby considerably limiting the development and testing time desired by the manufacturer. While it was not discussed in detail in the paper it goes without saying that in the design and installation of the circuit breakers safety was a paramount consideration. The illustrations will provide an index of this in the general arrangement of equipment, and also in the screen placed horizontally around the structure at the floor level to prevent curious small boys from climbing in to investigate.

Improvements in Moderate Capacity Oil Circuit Breakers

The increased duty requirements of power station service require circuit breaker design to give maximum interrupting capacity in a minimum of space. Compact, relatively high-power breakers having all three poles in a single round tank have been designed, which, in addition to increase in the rating for a given space, give improved performance over types previously available. The relations of the current-carrying loops inside the breaker and the diversity factor afforded by the common oil volume and air space give superior results in operation. This type of design permits use in current ranges where decreased arc energy, as compared to power handled, can be secured.

Abridgment of progress and problems from interconnection in Southeastern states

Great progress has been made. Interconnection between independent systems is primarily a protective measure, but the greatest economic benefits have been realized when the interconnections have been made by subsidiary companies of one holding company. The capacity of tie lines and the amount of power interchanges has developed greatly. The size of generating units has increased, as has the size of power plants, resulting in lowered cost per kw. The problem of satisfactory voltage and power factor control has increased in complexity as has that of system load dispatching. While much improvement has been made in oil circuit breakers, they still leave much to be desired. Interconnection has made possible more economical operation of existing plants and has resulted in the use of a larger proportion of the available water on systems combining steam, storage, and run-of-river hydroelectric plants. Long-time forecasting of load and rainfall conditions is important in economical system planning. The 110-kv. and 154-kv. line construction is discussed; also the value of ground wires and lightning arresters. The growing importance of carrier current for supervisory control and communication and their application are reviewed.

Progress and Problems From Interconnection in Southeastern States

Great progress has been made. Interconnection between independent systems is primarily a protective measure. The greatest economic benefits have been realized when the interconnections have been made by subsidiary companies of one holding company. The capacity of tie lines and the amount of power interchanged has increased greatly. The size of generating units has increased, as has the size of power plants, resulting in lowered cost per kw. The problem of satisfactory voltage and power factor control has increased in complexity as has that of system load dispatching. While much improvement has been made in oil circuit breakers, they still leave much to be desired. Interconnection has made possible more economical operation of existing plants and has resulted in the use of a larger proportion of the available water on systems combining steam, storage, and run-of-river hydroelectric plants. Long-time forecasting of load and rainfall conditions is important in economical system planning. The 110-kv. and 154-kv. line construction is discussed, also the value of ground wires and lightning arresters. The growing importance of carrier current for supervisory control and communication and their application are discussed.

High-Voltage Oil Circuit Breakers for Transmission Networks

High-Voltage Oil Circuit Breakers for Transmission Networks

Equipment for 220-Kv. Systems

This paper discusses the characteristics of equipment which have been found most suitable for use on 220-kv. systems or on extensive lower voltage systems. Consideration is given to general system design, governors of prime movers, generators, excitation systems, transformers, high-voltage oil circuit breakers, transmission line, and the equipment of substations. The result of four years' operation of a 220-kv. system have proven it to be as reliable as a 110-kv. system. The economies of 220-kv. transmission have been realized.

High-voltage oil circuit breakers for transmission networks

THE standards of the American Institute of Electrical Engineers define an oil circuit breaker as a “device (other than a fuse) constructed primarily for the interruption, in oil, of a circuit under infrequent abnormal conditions.” Common usage, however, has sanctioned the use of the term “circuit breaker” as applying to a device for the regular and usual interruption of an energized circuit as distinguished from a switch used only for opening circuits which are de-energized or not carrying load. This paper will consider only high-voltage oil circuit breakers, the term “high voltage” being taken as applying to potentials of 25,000 volts or above.