Lightning Arresters Research Articles

Operation of Lightning Arresters on Abnormal Power Frequency Voltages

Lightning arresters have historically been restricted in usage to operating voltages which are equal to or less than the arrester rated voltage as determined by the standard duty cycle test. This results in application limits which are unnecessarily conservative when considering the modern current-limiting gap station arrester.1 The current-limiting gap arrester has inherent overvoltage capability, and, through specific tests, it is possible to evolve application rules which allow use of these specific arresters on transient power frequency voltages above the standard arrester voltage rating.

Swithing Surge Voltages due to 500kV Disconnecting Switches Operation and Performance of Lightning Arresters

Swithing Surge Voltages due to 500kV Disconnecting Switches Operation and Performance of Lightning Arresters

TNA and Laboratory Study of the Switching-Surge Behavior of Lightning Arresters

Two different network configurations for 420 kV are examined on TNA simulating different possible types of lightning arresters to determine the discharge currents and energies through the arrester and their distribution as a function of the closing sequence of the breaker and of the switching impulse sparkover voltage of the arrester. The effect of the different possible characteristics of the magnetic active gap on the magnitude of the currents and on the residual voltage are examined.

Open Breaker Protection of EHV Systems

Although the use of line-entrance lightning arresters provides absolute protection for an open breaker condition, it represents a costly installation. No line entrance protection represents some risk of breaker damage. Line entrance rod gaps offer a compromise between these extremes. This paper discusses the probabilities of failures using these three alternatives and describes a procedure whereby the spacing of the line-entrance gap can be determined. Since this procedure depends on the particular configuration of the gap being used, test data are presented on one particular configuration used on a 345-kV system. Based on these data, recommended gap spacings for 345-and 500-kV systems are developed.

Phase-Phase and Phase-Neutral Switching Surges on 500-kV Open-Ended Lines

System insulation requirements on EHV systems, especially above 345 kV, are predominantly a function of switching surge overvoltages. Modem lightning arrester and circuit breaker technology and increased knowledge and understanding of insulation systems relative to switching surges have allowed substantial economics at higher transmission levels.

Switching Surge Operating Duty of Lightning Arresters

After mentioning different methods of testing the ability of an arrester to discharge long-duration switching surges, the artificial line discharge test with applied power frequency voltage is discussed. Oscillograms show that voltage transients during such tests may be influenced by the series gap of the test circuit. Test results agree fairly well with curves obtained from digital computations. Hence it appears justifiable to investigate by digital computations alone how test results are influenced by varying certain test- circuit parameters and the rate of rise of the arrester arc voltage. Computations were made for a 525-kV line and a modem 80 percent arrester. Particular mention is made of the disadvantage that could arise from too high a rate of rise of the arc voltage and of the fact that short lines can, in certain cases, impose a heavier duty on an arrester than longer lines.

Switching Surge Insulation Coordination: Lightning Arresters

Methods to determine the protection assured by a lightning arrester with reference to switching surge stress are discussed from a statistical point of view. Two methods are examined: the first considers the lightning arrester as a means to reduce the cumulative frequency of surge distribution, the second considers the arrester as a means to reduce the discharge probability of the insulation to be protected as a function of the prospective value of the applied surge.

Operating Duty of Lightning Arrester Against Switching Surges

Lightning arrester sparkover, caused by a switching surge, is considered. Under some circumstances large arrester currents flow and impose heavy duty upon the arrester characteristic elements and the series gap. Therefore, it is necessary to study previous relationships between the follow current and the circuit conditions and to test the current interruption ability of the arrester under various conditions.

Duty Cycle Testing of Current Limiting Station and Intermediate Lightning Arresters

The testing of lightning arresters has been reasonably well defined by ASA C62.1-1962, but the comparatively recent development of current limiting arresters makes it necessary to re-examine some industry standards to determine whether they provide adequate proof of current limiting arrester performance. The duty cycle test requires revision because it does not subject lightning arresters to a rate-of-rise of current comparable with what might be obtained in service. Tests must be made with higher rates-of-rise to insure that failure of loss of protective characteristics will not occur under actual service conditions.

Tests on Pressure Relief Devices for Station and Intermediate Lightning Arresters

Tests on Pressure Relief Devices for Station and Intermediate Lightning Arresters

Transmission-Line Discharge Testing for Station and Intermediate Lightning Arresters

Transmission-Line Discharge Testing for Station and Intermediate Lightning Arresters

Field Measurement of 345-Kv Lightning Arrester Switching Surge Perrormance

The purpose of this paper is to present lightning arrester switching surge voltages and currents, measured during a field test program on a 345-kv system. Surges were produced by energization of a transformer-terminated line and by ultra-high-speed re-energization (UHSR) of arrester-terminated lines. Arrester-sparkover levels were 1.1 to 1.7 pu (per unit) of arrester rating, and arrester follow-current peaks were 135 to 940 amperes.

Effect or Preceding Bias Voltage on Switching-Surge Operation of Spill Gaps and Lightning Arresters

Line-dropping tests on the Southern California Edison Company system showed that previously encountered spill-gap operation was not caused by extremely high switching-surge voltages, but by abnornally low sparkover of bushing-mounted gaps. In some cases lightning arresters also operated at abnormally low switching-surge voltages. Laboratory tests showed that a nonuniform gap field and trapped charges on the adjacent porcelain surface rendered spill-gap sparkover susceptible to wave front steepness and, particularly, to preceding voltages of opposite polarity. A gap located remotely from porcelain surfaces was found to be relatively free from these effects.

On the Characteristic Decision of the Lightning Arresters

On the Characteristic Decision of the Lightning Arresters

Stvdy of New Spark Gap of Lightning Arresters

Stvdy of New Spark Gap of Lightning Arresters

115-Kv Bus Switching Surges

In 1955, at the Black Dog Steam Station of Northern States Power Company (NSP), a 97-kv lightning arrester on the 115-2.4-kv reserve auxiliary transformer failed while de-energizing the 115-kv transfer bus with an air-break switch. The replacement of this arrester failed in 1957 when the 115-kv transfer bus was being energized through an air-break switch. These two arresters were not manufactured by the companies with which the authors are associated. Considering these failures as more than coincidental, a thorough investigation was initiated by NSP to attempt to explain how this transfer bus switching influenced the arrester failures. Analytical and Anacom (General Purpose Transient Analyzer) studies supplemented by field tests indicated sufficiently high overvoltages could be created by the transfer bus switch operation, due to a prestrike or restrike, to cause the lightning arrester to operate.

The international standardization of Lightning Arresters

This article briefly discusses the background and development of the International Electrotechnical Commission's Lightning Arrester Recommendations and compares corresponding provisions in the American Lightning Arresters Standard, C62.1 — 1957.

The International Standardization of Lightning Arresters

It can be concluded that the IEC Recommendation and the ASA Standard for valve-type lightning arresters contain essentially the same provisions. The IEC Recommendation, however, specifies maximum arrester protective levels and differs in other minor respects from the ASA Standard. Recognizing that the major issues have been resolved, and that the controversial provisions, in all probability, could also be resolved in future discussions, the US National Committee joined with 21 other national committees in voting unanimous approval of the valve arrester Recommendation. As a result, one more step has been taken toward the international standardization of all products offered in world trade.

Lightning Arrester Field Test Equipment and Results

Lightning arresters play an important role in the protection of power system insulation against damage by surge voltages. Many arresters which have been in service a considerable number of years are still expected to provide this protection even for insulation that may not possess the strength as specified for new apparatus. The results of various methods used in the past to check arrester condition in the field are often questionable. A novel field test method for lightning arresters has therefore been developed. Impulse sparkover and power frequency leakage tests in the field can be carried out, with portable test equipment, on line-type and station-type lightning arresters with single-unit ratings up to 37 kv. Design and operating principles of this equipment are described; the field test results indicate that with the new method it is possible reliably to detect arresters not performing according to requirements.

Surge transfer through 3-phase transformers

ALTHOUGH a low-voltage circuit, connected to the system by a transformer, has no direct exposure to lightning, lightning surge voltages can be produced in this circuit as a result of surge voltage impact on the high-voltage side of the transformer. Even though a lightning arrester is connected on the high-voltage side of the transformer, surge voltages transferred to the low-voltage side can be dangerous especially to lower BIL equipments such as rotating machines and dry-type transformers.