Breaker Failure Research Articles

The San Salvador Earthquake of October 10, 1986—Performance of Lifelines

Although the October 10, 1986 San Salvador earthquake was only a moderate event of magnitude 5.4 and the recorded ground motions had a relatively short duration, the high recorded peak accelerations caused substantial damage to lifelines. There was significant and widespread damage to buried lifelines. Long-distance telecommunications facilities were reportedly undamaged, but there was substantial loss of local phone service caused by damage to buildings, failures of equipment racks, and loss of emergency power (tilting of batteries). Power generating facilities (hydroelectric and geothermal) that supply electricity to San Salvador are located too far from the city to have been affected by the earthquake. Both 115-kV substations that serve San Salvador experienced a moderate level of damage, consisting mostly of ceramic column circuit breaker failures. As has been observed in past earthquakes, control and instrumentation systems and low-voltage power-supply equipment displayed an ability to withstand high ground accelerations.

Station-initiated outages in composite-system adequacy evaluation

Failure events originating in terminal stations can result in multiple outages of generators and/or lines or loads in a power system. Failures of breakers, transformers and busbar sections are major causes of these multiple outages. The effect of these outages in composite-system reliability evaluation can be quite significant. The effect of station-related multiple outages can be quite dominant and may, therefore, obviate the need to consider higher-order independent outages of major components such as generating units, transmission lines and transformers. In this paper, models are presented and discussed for various possible failure events originating in the stations. Expressions in terms of probability and frequency of appropriate states are developed for each of the failure events. These expressions are then utilised in the adequacy assessment of a composite 6 busbar test system.

Effect of Station Originated Outages in a Composite System Adequacy Evaluation of the IEEE Reliability Test System

The reliability evaluation of a bulk power system normally includes the independent outages of generating units, transformers and transmission lines. Station originated outages, can, however, also have a significant effect on the composite system adequacy indices. Terminal station related failure events such as failures of breakers, transformers and bus sections are a major cause of multiple outages of major cxxponents (generators and/or transmission lines etc.). This paper illustrates the effects of terminal stations in composite system reliability evaluation by using the IEEE Reliability Test System (RTS). The paper also provides a valuable extension of the original RWS by including switching configurations at each bus.

Discrete-event simulation of load point interruptions

A discrete-event simulation system has been created for obtain ing probability distributions of load point reliability indices in an electricity supply system. The modeled behavior of transmis sion components includes temporary and permanent faults, com mon mode faults, maintenance, switching after permanent fault, breaker failure to open, closing of normally opened breakers, and fluctuating weather environment. Also, the simulation system can study the effect of parameter uncertainty when there is limited component outage data or weather data.

Advances in Capacitor Starting

An 8000-hp motor at the LOCAP Pipeline Clovelly Station is brought on line with three step capacitor starting and is protected from resonant overvoltage by a large metal oxide voltage limiter. Three-step starting is required to stay within the utility requirement of a maximum of ±1.5 percent primary voltage fluctuation during the entire starting operation. Cycle timers are utilized to obtain critical breaker sequencing as well as protect the system from breaker failure. Should the utility power fail while the motor is accelerating, the starting capacitor may cause severe motor overvoltage. Zinc oxide limiters are sized to absorb 1 MJ over a period of ten cycles allowing the breakers to clear the motor and capacitors.

Transient Recovery Voltage Failures of Two 15 kV Indoor Oilles Circuit Breakers

Two recent cases of sequential failures of indoor oilless circuit breakers in power plant electrical distribution systems have demonstrated the need to establish transient recovery voltage (TRV) performance standards for such circuit breakers and to incorporate TRV analyses into the design basis of power plant electrical distribution systems. Current industry standards do not require breaker manufacturers to demonstrate or state TRV capability. Users must, therefore, establish the TRV parameters for their systems and include these data in their breaker specifications to ensure that the breakers will provide the required system protection.

Summary Update of Practices on Breaker Failure Protection

In the July/August 1970 issue of IEEE Transactions on Power Apparatus and Systems, an IEEE committee report was published entitled "Local Backup Relaying Protection." That report compiled the results of a survey on the current preferences on duplicate relays, dc and ac sources, control power, and breaker failure protection. Since that time, the industry has gained experience with breaker failure schemes and practices are much better defined. These practices have been compiled and are submitted in this report.

Summary Update of Practices on Breaker Failure Protection An IEEE Power System Relaying Committee Report

Summary Update of Practices on Breaker Failure Protection An IEEE Power System Relaying Committee Report

Diagnostic Technique for Mechanical Failures of Gas Circuit Breakers

Experimental studies have been made to develop an effective technique for diagnosing mechanical failures of SF6 gas circuit breakers (GCB) from the outside. In order to verify the effectiveness of this methods, GCB was assembled, simulated defective parts being included, and was operated at a very low operating speed. The changes of the driving force, vibratory acceleration and stroke of the moving parts were measured during such operation.

Microprocessor Implementation of Breaker-Fail Protection

This paper describes the implementation of a digital technique for breaker-fail protection, using rate of rise of current at zero crossings as an indicator of current magnitude. Results obtained on a PDP 11/10 computer for single and multiple circuit breaker failure (with and without C.T. saturation) are given. The potential for implementation of the protection algorithm on an 8 bit microprocessor is discussed.

Synthetic Methods for Testing of Vacuum Breakers

Different synthetic methods are scrutinized as to the applicability to vacuum breakers. Skeats method with resistor is brought forward and discussed from the viewpoint of breaker failure modes, interruption and circuit phenomena. Criteria for choice of resistor are given. Comparison tests using this method and direct method were performed. The results support theoretical conclusions by experimental verification of equivalency for the tested vacuum breaker. The method offers practical and economical advantages over current injection and is also suitable for multiloop and duty cycle testing.

On the Statistics of Multi-Break Circuit Breakers-Thermal and Dielectric Regimes

This paper studies the statistical performances of multi-break circuit-breakers. For the thermal reignition regime, a formal proof is given of the fact that under certain conditions (explicitly derived) the overall performance of a multi-break breaker is better than that expected from a proportional extrapolation of the results from a single break. For the dielectric regime, it is shown that the hitherto published formulas are conservative in the sense that they overestimate failure probabilities. Using these formulas, graphs are given which compare the failure probabilities of a four-break breaker in the dielectric regime with that of a single break under certain given fractions of the stress on the complete pole. Some general results of a statistical nature relating complete circuit breaker failure probabilities in the dielectric regime to a single break failure probability are also given.

Effects of Future Turbine-Generator Characteristics on Transient Stability

Future turbine-generator unit designs, particularly for the larger ratings, are expected to have greater generator reactances and lower unit inertias. Transient stability limits are determined for the future designs in terms of critical fault clearing times for faults on the high voltage transmission lines at the power plant substation. Transient stability limits of the future designs are compared with representative existing generating unit designs. Stability performance of future turbine-generator designs will be very similar to existing designs when considering their respective breaker failure (backup) relay system capabilities. Approximate gains in transient stability critical fault clearing times are also listed when applying various feasible stability control techniques.

Conemaugh Project New Concepts for 500-kV System Protection

The Conemaugh 500-kV system stability studies indicated that stability was achieved for all faults that were cleared in 4.5 cycles. If a breaker fails to clear a 3-phase fault, it is necessary to resort to a breaker failure timing scheme of 7.5 cycles and to down grade the fault to a single phase-to-ground fault by independent pole operation of the circuit breaker in order to maintain stability. To cover abnormal conditions when instability may still occur, out-of-step relays on generators are being applied to trip the unit when the first unstable swing appears in the unit transformer.

Local Backup Relaying Protection

Results of a survey and symposium on local backup relaying protection is presented. The survey covers the responses of 121 relay engineers to questions pertaining to their present-day preferences on duplicate relays, dc and ac sources, control power, and breaker failure protection. The symposium offered the opportunity to present detailed philosophy, circuit configuration, and explanations to supplement the statistics compiled in the survey.

Experience with oil circuit reclosers on REA systems

For three years surveys have been made of the operation of small single-pole automatic reclosing oil circuit breakers (also called “oil circuit reclosers” and “service restorers” <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> ) on rural electric distribution systems financed by the Rural Electrification Administration. Results of these surveys indicate that the ratio of lockouts to operations is less than five per cent in most cases, and that there are from four to nine operations per month per breaker during the spring and summer, with each breaker controlling about 20 miles of line. The number of breaker failures and other breaker difficulties have been a small percentage of the total number of breakers installed. These surveys, together with discussions with system managers, have indicated that automatic reclosing breakers offer many advantages for rural line sectionalizing. Presently available breakers can be much improved in operating characteristics, and new sectionalizing devices are needed. This paper presents suggestions for such improvements.

Experience With Oil Circuit Reclosers on REA Systems

For three years surveys have been made of the operation of small singlepole automatic reclosing oil circuit breakers (also called ``oil circuit reclosers'' and ``service restorers''1) on rural electric distribution systems financed by the Rural Electrification Administration. Results of these surveys indicate that the ratio of lockouts to operations is less than five per cent in most cases, and that there are from four to nine operations per month per breaker during the spring and summer, with each breaker controlling about 20 miles of line. The number of breaker failures and other breaker difficulties have been a small percentage of the total number of breakers installed. These surveys, together with discussions with system managers, have indicated that automatic reclosing breakers offer many advantages for rural line sectionalizing. Presently available breakers can be much improved in operating characteristics, and new sectionalizing devices are needed. This paper presents suggestions for such improvements.

Analysis of the Failures of Oil Circuit Breakers

Analysis of the Failures of Oil Circuit Breakers

Analysis of the Failures of Oil Circuit Breakers

Analysis of the Failures of Oil Circuit Breakers

Transmission System Relay Protection-III

A paper was presented in 1919, followed by Part II in 1921, giving a resumé of the relay protective systems up to those dates. The various important developments since 1921 warrant a third paper on this subject. There has been a general realization of the importance of shortening the time for removing a fault, and this has led to the production of high-speed circuit breakers combined with very fast relays, the total time of clearing trouble being reduced to from two to eight cycles. There is a tendency towards types of relays and schemes which are inherently selective in operation, such as the ``distance'' relays, balanced or differential schemes, pilot wire relays, etc. Due to the increased reliability of service and to the relative ease of obtaining selectivity and high speed of the relay protective system the growth of the use of parallel lines (usually in pairs) has been rapid. Back-up protection against through short circuits or failures of relays or breakers at the succeeding stations is growing in use and the necessary relays are being added unless the scheme adopted inherently has this covering protection. Due to its fundamental advantages of the detection of a fault in its incipient stage thereby reducing the voltage disturbance to the system, minimizing the damage at the fault, and reducing the stress on the circuit breakers ground protection is approaching the importance of becoming the first line of defense.