Circuit Breaker Duty Research Articles

Feasibility Study of Superconducting Cable Application to Oil/Gas Power Supply Network

In this paper, the static and dynamic behaviors of a power system feeding an oil/gas plant with superconducting (SC) cables are investigated. SC cables have been expected to provide more efficient power supply and less space utilization for power systems compared to conventional cables. On the other hand, their compatibility with the existing power systems has not yet been clarified. In this paper, taking a typical distribution system in an oil/gas plant as an example, we designed high-voltage SC cables and investigated their compatibility with the system from the viewpoint of static and dynamic performances. The voltage distribution under steady-state operation and the transient voltage and current during fault conditions were examined and compared with the case of conventional cables. The results show that, in addition to the efficiency enhancement, SC cables could be applied without any further constraint on circuit breaker duties and insulation coordination requirements.

Evaluating Generator Circuit Breakers Short-Circuit Duty Using IEEE C37.010 and C37.013

This paper describes a procedure for calculating generator circuit breaker duty. Currently, commercially available software products help in determining the duty for a general-purpose circuit breaker. However, further calculations are needed to determine the duty for a special-purpose generator circuit breaker. IEEE Std C37.010-1999 provides the calculation procedure for general-purpose circuit breakers. In order to evaluate a special-purpose generator circuit breaker, this paper will expand the steps and methodology used in IEEE C37.010-1999 by presenting a procedure and detailed calculations for finding a duty multiplication factor based on the test X/R ratio of generator circuit breakers given in IEEE C37.013-1997 (Standard for AC High-Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis). This way, engineers can still make a generator circuit breaker assessment although generator circuit breaker evaluation module is not included in many commercial short-circuit programs.

Effect of Voltage Recovery Rates on Interrupting Performance of Air-Blast Circuit Breakers [includes discussion

Recovery rate is the term applied to the rate at which voltage rises across a circuit breaker immediately following interruption. Before high-voltage air-blast circuit breakers can be economically applied, a thorough knowledge of the relationships between circuit-breaker duties and recovery rates on systems is necessary. Whereas the performance of the modern oil circuit breaker is relatively unaffected by circuit recovery rate, the authors have found that this factor has a very significant effect on the performance of the radial-type air-blast circuit breaker. Using the minimum pressure required to produce successful interruption as a measure of circuit severity on the circuit breaker, an empirical relationship correlating the influence of both current and recovery rates has been found. As shown by this relationship, reduction of the inherent recovery rates by using linear resistors may be desirable in those circuits possessing unusually high rates. Until the relationships between system recovery rates and circuit-breaker duties have been correlated, it is advisable to apply these circuit breakers only where these factors and the circuit-breaker characteristics are both understood.

Out-of-phase voltage effects in circuit breakers

THE POSSIBILITY THAT transmission-line circuit breakers may be subjected to as much as double normal line-to-ground voltage if opened during a system disturbance when sections on either side of the circuit breaker are out-of-phase has been recognized by manufacturers and operating personnel for a long time. However, only a few isolated cases of trouble have been traced to this exceptional circuit-breaker duty, and therefore it has not been felt justifiable in circuit-breaker specifications to insist on proved ability to handle double voltage interruptions. Experience indicates that many circuit breakers have struggled through out-of-phase operations by continuing to arc until separating parts of the system have swung sufficiently in phase again to permit interruption.

The efficient rating and disposition of supply apparatus on high-voltage urban systems

The paper presents a technical approach to the problems of safe and economical control and operation of certain power networks. The initial sections are devoted to a quantitative discussion on circuit-breaker duty and short-circuit phenomena at points of supply and at remote points on the network. Some effects of interconnected working are indicated. Means for current limitation and alternative methods of control under fault conditions are described. The design and protection of cable networks are reviewed and the characteristics of transformers briefly discussed. Finally, some comments are offered on the layout of mediumvoltage apparatus and on the problem of voltage variation at consumers' terminals. The discussion is confined to phenomena on urban networks operating at voltages not exceeding 11 kV.

"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.