Surge Absorber Research Articles

A Surge Absorber for the Sri Lankan Distribution Substation to Mitigate Lightning Damage

Due to high grounding resistance and soil conditions surge arrester performance decreases. Even though in installation the standard earthing resistance is achieved with time the earthing resistance would be at a high value. When a high voltage arrives at the surge arrestor it discharges the excess voltage by providing low impedance shunt path to ground and providing protection for the transformer. Because of high impedance path the voltage would not divert to the ground and carry on its original path and damage the transformer. Therefore, for areas with high earthing resistances protection must be improved for distribution substations. Throughout this research method of reducing the peak and the rate of rise of surge was analyzed for providing extra protection for the transformer. The selected substation was AV047 it was selected because of lightning occurrence in the selected area, Replacement of the transformer due to damages cause by overvoltage surges and high earthing resistance of the installed substation. Usage of the surge absorber for additional protection was investigated throughout the research. By this method proposed by the research group it was able to provide the sufficient protection for the transformer during surge conditions and reduce the peak and the rate of rise of the surge. Losses of the surge absorber were also analyzed at different conditions. Further an algorithm was developed so that the surge absorber could be implemented to any MV and HV networks for protection of the transformer.

Permeance Based Design and Analysis of Supercapacitor Assisted Surge Absorber for Magnetic Component Selection

AbstractSupercapacitor assisted surge absorber (SCASA) technique is a unique and commercially useful design approach for surge protector devices. SCASA topology is based on the combination of a coupled inductor which partly acts as a transformer, and a supercapacitor sub-circuit. In developing the first commercial product, the research team had to optimize the selection of the magnetic core, based on empirical approaches and industry price constraints. This paper presents a permeance-based design and analytical approach to SCASA, with the topological details of its first successful implementation. While existing SCASA topology performs satisfactorily, this research elucidates design techniques to improve surge absorption by 60% and reduce load clamping by 10% based on high-performance prototypes developed using High-Flux and X-Flux toroids. The test results presented in this research are validated by experimental work carried out in a high-voltage surge laboratory using Noiseken LSS-6230 lightning surge simulator adhering to IEEE C62.41/IEC 61000-4-5 standards. Surge immunity of SCASA prototypes was evaluated using international test procedures of UL-1449 3rd edition standard. Index TermsMagnetic permeance, SCASA, Supercapacitor, Surge protection, Transient absorption

Magnetic Design Aspects of Coupled-Inductor Topologies for Transient Suppression

Based on the discovery of the surge absorption capability of supercapacitors, a transient protector named supercapacitor-assisted surge absorber (SCASA) was designed and implemented in a commercial device. Despite its simplicity, the circuit topology consisted of a coupled inductor wound around a specially selected magnetic core. This paper elucidates the design aspects of SCASA coupled-inductor topologies with a special focus on the magnetic action of core windings during transient propagation. The non-ideal operation of the SCASA transformer was studied based on a semi-empirical approach with predictions made by using magnetizing and leakage permeances. The toroidal flux distribution through the transformer was also determined for a 6 kV/3 kA combinational surge, and these findings were validated by using a lightning surge simulator. In predicting the possible effects of magnetic saturation, the hysteresis properties of different powdered-iron and ferrite core types were considered to select the optimal design for surge absorption. The test results presented in this research revealed that X-Flux powdered-iron toroid and air-gapped EER ferrite yielded exceptional performance with ∼10% and ∼20% lower load–voltage clamping compared to that of the existing Kool μu design. These prototypes further demonstrated a remarkable surge endurance, withstanding over 250 consecutive transients. This paper also covers details of three-winding design optimizations of SCASA and LTSpice simulations under the IEC 61000/IEEE C62.45 standard transient conditions.

Importance of Leakage Magnetic Field and Fringing Flux in Surge Protector Design

Transient surge absorption capability of supercapacitors is practically implemented in a commercial surge protector known as supercapacitor assisted surge absorber (SCASA). It is a low component count high performance circuit design which utilizes a coupled inductor topology wound to a powdered-iron magnetic core. This paper investigates non-ideal characteristics of the SCASA transformer designed using various air-gapped ferrites such as manually gapped toroids and mass-produced commercially available EER cores. Emphasis is given to examine surge energy losses associated with leakage magnetic field and fringing flux of gapped transformer prototypes. In predicting effects of an air gap in ferrite materials, an analytical approach based on effective-permeance is used with validations based on SCASA inductance properties. Experimental work presented in this paper are carried out using a Noiseken lightning surge simulator adhering to IEC 60038 and IEEE C62.41 standards. In addition, SCASA prototypes were subjected to surge immunity tests specified by UL-1449 Underwriters' laboratory procedures, where a 10% reduction of load-voltage was recorded outperforming the present design.

Supercapacitor assisted surge absorber technique: high performance transient surge protectors for consumer electronics

Invention of the transistor in 1947 made a radical change to the path of the development of electronic products and systems. In the mid-1950s, integrated circuits (ICs) started evolving rapidly, creating miniaturized analog, digital and mixed signal circuits. By the 1960s to 1970s, microprocessors, memories and power semiconductors entered the electronic marketplace. During the 1980s and 1990s, power supplies required to power the high-performance digital circuits kept dropping towards 2 V and below. By the year 2000, complex digital and mixed- signal circuits required for portable gadgets were powered by very low dc rails as low as 1 V and sub-1 V. Very large-scale ICs and ultra-large scale ICs proliferated after 2000, integrating millions to billions of sub-micron feature transistors. The ultimate result of this massive progress came with the unique problem of vulnerability of modern electronics to transient surges. A detailed background to this is presented in Chapter 1 of reference <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> .

Optimization of Supercapacitor Assisted Surge Absorber (SCASA) Technique: A New Approach to Improve Surge Endurance Using Air-Gapped Ferrite Cores

SCASA is a patented technique commercialized as a surge protector device (SPD) that adheres to UL-1449 test standards. Apart from the novel use of supercapacitors, SCASA design incorporates a coupled-inductor wound to a specially selected magnetic material of powdered-iron. In this study, we investigate the limitations of the present design under transient operation and elucidate ways to eliminate them with the use of air-gapped ferrite cores. In modelling the operation under 50 Hz AC and transient conditions, a permeance-based approach is used; in addition, non-ideal characteristics of the transformer core are emphasized and discussed with empirical validations. The experimental work was facilitated using a lightning surge simulator coupled with the 230 V AC utility mains; combinational surge-waveforms (6 kV/3 kA) defined by IEEE C62.41 standards were continuously injected into SPD prototypes during destructive testing. Such procedures substantiate the overall surge-endurance capabilities of the different core types under testing. With regard to optimizations, we validated a 95% depletion of a negative-surge effect that would otherwise pass to the load-end, and another 13–16% reduction of the clamping voltage verified the effectiveness of the methods undertaken. In conclusion, SCASA prototypes that utilized air-gapped cores revealed a greater surge endurance with improved load-end characteristics.

Supercapacitor-Assisted Techniques and Supercapacitor-Assisted Loss Management Concept: New Design Approaches to Change the Roadmap of Power Conversion Systems

All electrical and electronic devices require access to a suitable energy source. In a portable electronic product, such as a cell phone, an energy storage unit drives a complex array of power conversion stages to generate multiple DC voltage rails required. To optimize the overall end-to-end efficiency, these internal power conversions should waste minimal energy and deliver more to the electronic modules. Capacitors are one of the main component families used in electronics, to store and deliver electric charges. Supercapacitors, so called because they provide over a million-fold increase in capacitance relative to a traditional capacitor of the same volume, are enabling a paradigm shift in the design of power electronic converter circuits. Here we show that supercapacitors could function as a lossless voltage-dropping element in the power conversion stages, thereby significantly increasing the power conversion stage efficiency. This approach has numerous secondary benefits: it improves continuity of the supply, suppresses voltage surges, allows the voltage regulation to be electromagnetically silent, and simplifies the design of voltage regulators. The use of supercapacitors allows the development of a novel loss-circumvention theory with applicability to a wide range of supercapacitor-assisted (SCA) techniques. These include low-dropout regulators, transient surge absorbers, LED lighting for DC microgrids, and rapid energy transfer for water heating.

Power supply system for KSTAR neutral beam injector

The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120kV/70A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600V and the high voltage rectified transformers to supply DC voltage of 20kV, 30kV, and 50kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5kV/5A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to accelerator grid. This paper presents configuration and features of power supply system, main controller, and interlock system of KSTAR NBI.

Novel SnO2 ceramic surge absorbers for low voltage applications

To make SnO2–CoO–Nb2O5–Cr2O3–Y2O3–Bi2O3 ceramics suitable for low voltage varistor applications, the amount of Bi2O3 addition to a well-known SnO2-based composition for high voltage varistors was optimized. The addition of 0.15mol% Bi2O3 has resulted in a single phase ceramic material with the average grain size of 30μm and electrical properties useful for low voltage varistors. The obtained SnO2 low voltage varistors exhibit excellent electrical properties as surge absorbers.

22.9kV 수전설비에서 측정된 과도과전압의 특성

The aims of this paper are to characterize the transient overvoltages(TOVs) and to evaluate the risk occurring at 22.9kV consumer’s substation. The measurements of lightning- and switching-caused TOVs were made during Mar. 2013 and Feb. 2014. As a consequence, 47 events of TOVs were recorded and 4 of them were higher than the input voltage envelope(IVE) of the information technology industry council(ITI) curve. The measured TOVs are characterized by longer front times and longer durations compared to the 1.2/50㎲ standard impulse voltage waveform, and some of them represent bipolar waves with lower oscillation frequencies. It suggests that the test of non-standard impulse voltage waveforms is needed for effective risk assessments of power apparatus. Lightning- and switching-caused TOVs exceeding IVE of ITI curve are induced at the secondary of 22.9kV potential transformer(PT). We may, therefore, conclude that the surge protection devices should be applied at the secondary of PT and the surge absorbers should <BR>be installed at the primary of VCB or PT. The results presented in this paper could be useful to design the reasonable insulation coordination for 22.9kV consumer’s substation.

진공차단기 스위칭 써지 특성 해석 및 저감 방안

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

The Performance Evaluation of Surge Absorber Contained Low Voltage Distribution Equipments by Lightning Impulse Test

In these days, integrated circuits have been increasingly used for Low Voltage (hereinafter LV) distribution equipments for the purpose of making more multi-functional and downsizing. However insulation of the circuits is easily broken by lightning surge from the power line, so the number of troubles is also getting increased. On the other hand, there is no authorized standard value of the lightning withstand performance for LV distribution equipments. Here, we implemented Lightning Impulse Withstand Voltage (hereinafter LIWV) test and Lightning Impulse Withstand Current (hereinafter LIWC) test in order to verify the value. As a result, we made it clear that if LV distribution equipments’ integrated circuits are protected by surge absorber, the lightning withstand performance is determined not only by LIWV performance but also by the performance of surge absorber, i.e. LIWC test should be implemented for the performance evaluation.

A microgap surge absorber fabricated using conventional semiconductor technology

A new type microgap surge absorber fabricated by only semiconductor technique has in it a special structure silicon chip which forms microgaps for gas discharge with electrodes, and has advantages such as small size, low cost, suitability for mass production besides the desirable characteristics that common microgap surge absorbers have. Applications of this absorber in communication facilities are discussed.

Electrical characterisations of new microgap surge absorber fabricated by using conventional semiconductor technology

The structure of the microgap and the manufacturing processes for a new type of microgap surge absorber, fabricated by semiconductor technology, are described. A very stable spark-over voltage with a narrow distribution was obtained by coating the metallic films in the microgap. As well as the desirable characteristics of common microgap surge absorbers, this new type of microgap surge absorber has other advantages such as small size, low cost and suitability for mass production.

Field emission silicon surge absorber

Various studies are currently being conducted on microelectron source for its product applications. Having noted the high-speed properties of electrons issued from an emitter in a vacuum, we applied these to surge absorbers. Absorption properties and service life in surge voltage applications are crucial factors in rating surge absorbers. Tests confirmed that our surge absorber had absorption superior to conventional surge absorbers and that service life remained stable after some 10,000 surge voltage repetitions. Observation of the emitter after surge voltage application showed localized melting, indicating that emission concentrated in one area, causing the observed melting.

Low Surge Vacuum Circuit Breakers

Low surge vacuum circuit breakers were developed which used a new electrode material cobalt-silver-selenium alloy. Their chopping current level was below 1.0 A and their high frequency current interruption ability was about 24 Aús. These levels were much lower than those of conventional electrode materials and did not change after load current interruption lifetime and short circuit current interruption tests. From switching tests with motors and no-load transformers, safe operation of these vacuum circuit breakers, without any surge absorber, was confirmed ; the surge level caused by current chopping and the multiple reignition surge level caused by high frequency current interruption were far below the apparatus insulation levels. Furthermore, the new material showed good interruption ability.

Discharge Processes in a Low-Voltage Microgap Surge Absorber

Discharge processes in the newly developed microgap surge absorber (MSA) are studied using a photomultiplier and image converter camera. The MSA is for the protection of low-voltage circuits from overvoltage surges and consists of a semiconducting thin film coated on a ceramic tube with microgaps which are made by removing annular rings in the coated film by a laser beam. The highly desirable characteristics of the MSA as a surge absorber result from the microgap which supplies initial electrons and triggers a surface streamer to build up a glow discharge.

On the Effects of Surge Absorbers-Part II. Numerical Results

The results are given of a numerical evaluation of the equations corresponding to the output voltage from a surge absorber, as derived in Part I. Curves have been plotted to show how the constants of the absorber, and the capacitance of the capacitor simulating the transformer, affect the wave form of the incident surge. As it is the main function of the surge absorber to reduce ‘the voltages induced in the apparatus connected to it, a comparison has been made between the stresses produced in a transformer due to a unit step surge with and without the presence of the absorber.

On the Effects of Surge Absorbers-Part I, Analytical Foundation

The work presented here deals with the effects of a simple surge absorber composed of an ordinary choke coil, and connected in series with the line ends of a power transformer. The study includes the effect of such absorbers on the wave form of the incident surge, and consequently on the voltage distribution along the high voltage transformer windings. Moreover, a sample set of calculations has been performed to find out the way, the absorber constants, and the transformer simulating capacitor capacitance, contribute to those effects. These calculations are included in the second part of the work.

The surge protection of power transformers

The paper commences by reviewing the methods adopted for the protection of overhead lines and transformers from the incidence of lightning. Itis then pointed out that in manycases it is not economic, and in others technically difficult, to provide sufficient line protection, so that transformers connected to such lines are likely to be subjected to transients having high voltage-amplitudes and high time-rates of voltage change. The question of transformer winding breakdown due to transients is then reviewed and evidence is brought forward to show that the important stresses are those between coils and turns and not those in the major insulation. The conclusion drawn is that transformers can advantageously be protected in most cases by those wave-flatteners which, under all conditions, permit only safe rates of voltage-change to exist at the terminals. Three representative wave-flatteners—condensers, inductance coils, and surge absorbers—are then discussed and equations are given which indicate the manner in which their performances are calculated, consideration being given to all degrees of lightningconditions, including those which cause flashover near the protected transformer. Then follows an experimental analysis of the axial stresses, and their reduction by the use of wave-flatteners, in various transformer windingsunder travelling-wave, travelling-wave flashover, and direct lightning-stroke conditions. Several transformers, differing in rating, mode of winding, natural frequency, and value of a. are employed. The results are presented in the form of gradient-distribution curves so that the relative performances, under various conditions, of the three kinds of flattener may be readily examined and the effects of changes in transformer constants compared. Inthe Appendix are derived the equations of the surge absorber.