Surge Protection Research Articles

Experimental Study on the Effectiveness of Emerged and Submerged Coastal Bio-Shield in Storm Surge Protection

Surges and waves induced by cyclones and other severe storms can cause devastating damage of property and loss of life in coastal areas of Bangladesh. Bio-shield in wetlands can reduce the energy of storm surges and cyclones. To study the effectiveness of emerged and submerged coastal bio-shield in storm surge protection, a laboratory experiment was carried out in a 22 m long, 0.75 m wide and 0.75 m deep wave flume in the Hydraulics and River Engineering Laboratory of Bangladesh University of Engineering and Technology (BUET). Experiments were carried out for investigating the performance of the bio-shields in submerged as well as emerged conditions. Bio-shields were represented by cylindrical bamboo sticks as rigid bio-shield and polyethylene as flexible bio-shield whose diameter was 6 mm. There were a total of 51 experimental runs covering 3 different wave periods of 1.6, 1.8 and 2.0 seconds. Time-series of water surface elevations for vegetated (with bio-shield) and non-vegetated (without bio-shield condition) were compared to identify the influence of bio-shield on wave height reduction. It is found for emerged and submerged conditions of bio-shield that the maximum wave height reductions are 71% and 52% at a location which is 3.5 m away from the embankment for wave periods of 2.0 sec at bio-shield spacing of 50 mm c/c and 25 mm c/c respectively. These reductions of wave heights occur when bio-shield of 2 m width (1 m Rigid + 1 m Flexible) are placed at 4 m distance from the embankment. Hence, the most effective position for maximum wave height reduction by both emerged and submerged bio-shield of 2 m width is 4 m distance from the embankment. It is anticipated that these results will find broad application in coastal management and planning for areas with existing coastal bio-shield as well for bio-shield restoration and establishment efforts.

Advanced Fast Large Current Electronic Breaker Using Integration of Surge Current Suppression and Current Divider Sensing Methods

Electronic breakers or fuses are most widely used tools to protect the electric-driven facilities from overload or short circuit. However, they may suffer from two major drawbacks: (1) it normally takes more than 0.1 s to react, resulting in facilities not sufficiently protected, and (2) a higher rating size of breakers or fuses is demanded than expected due to lack of a surge current suppression mechanism. To overcome these problems, this paper proposes a fast large current electronic breaker based on the integration of current divider sensing and surge suppressing methods. The load surge current can be effectively suppressed by series negative temperature coefficient (NTC) thermistors. The load current is then divided into a small portion and converted to a voltage signal for amplification and comparison with the predefined threshold value, i.e., the maximum load tolerance current. AC power will be disconnected immediately by the switching circuit once the load current exceeds the tolerance value. The disconnection of power supply will continue for a period of time set by the timer. The experimental results verify that the proposed electronic breaker can provide a large load current protection up to 20 A under effective surge suppression within 10 ms.

Numerical analysis and parametric optimization of surge protection devices in a long up-pumping water pipeline

This study aims to present a parametric analysis of combined use of two surge protection devices in a relatively very long up-pumping water supply pipeline. Transient conditions are induced by sudden pump tripping. The effects of four parameters of hydropneumatic tank, i.e., polytropic exponent, initial air volume, orifice diameter and wave celerity and two parameters of surge tank, i.e., tank volume and tank orifice diameter are investigated on pressure surges. The parameters are optimized to achieve reduced pressure fluctuations throughout the pipe length. A numerical model is developed to perform hydraulic transient analysis in the pipeline system. Governing partial differential equations for unsteady flows are solved by the method of characteristics (MOC) and are subsequently converted into algebraic form using finite difference method. To establish the authenticity of the model, it is experimentally validated by comparing the model results with the experimental results. The validated model is then employed to analyze the effects of various parameters of the two surge protection devices on pressure fluctuations along the pipe length. The results obtained from the study are optimized for safe operation and economic use of the system.

Analysis of the Conduction Process for Active Surge Protection Gap With Combination Wave Energy Injection

In this paper, we designed an active coupling trigger circuit and an active surge protection gap (ASPG). The surge protection level of the passive SPG is improved, and the operating time of the passive SPG is shortened. The equivalent circuits for the coupling trigger circuit were developed. Then, we analyzed the component transient voltage of the active coupling trigger circuit with the combination wave injected. We obtained the numerical relationship between the coupling trigger current and the current flowing through the ASPG. In addition, the timing relationship between the component voltage and the current was acquired. To verify the analysis results, we established the combination wave generator and conducted an experiment. In the experiment, we observed that the trigger circuit operating time and the ASPG impulse breakdown voltage changed with the capacitor charging voltage of the combination wave generator. Furthermore, we discovered the change laws. The results also show that the operating time and impulse breakdown voltage of the ASPG are both smaller than the passive SPG. These results provide an important theoretical and experimental basis for the further study and structural optimization of the ASPG.

Improving the reliability of the compressor unit using the wavelet transform method

Centrifugal compressors are an integral part of modern production in such industries as gas transmission, oil refining, metallurgical, machine-building, mining, as well as in electric and heat power engineering. Interruptions in the operation or failures of compressors lead to decrease in profit or large material loss. Conditions should be created for the safe (stable) operation of centrifugal compressors. Surge is global (complete) loss of stability, an unacceptable phenomenon for a centrifugal compressor. Compressor surge protection must function during operation. The algorithms used to protect centrifugal compressors against surge have some drawbacks, which makes it impossible to reliably prevent surges. There are many methods for analyzing rapidly changing processes in the flow part of a centrifugal compressor. The wavelet theory is the most accurate and modern method. The use of the wavelet transform method for signal processing allows us to solve the problems of analyzing non-stationary processes of a centrifugal compressor to expand the acceptable range of work and build reliable operation of the anti-surge diagnostic system. In the future, it is possible to use other basic wavelet functions, for comparison and selection of the most suitable one, for the analysis of unsteady signals in a centrifugal compressor.

Circuit Level Model of Miniature Circuit Breakers

We present a black-box model of miniature circuit breakers having a realistic physical background. In compliance with basic physics, engineering know-how and magneto-hydro-dynamics arc simulations, two sets of differential-algebraic equations are derived to model air plasma chemical dynamics and its interaction with breaker's physical environment (chamber shape, splitter plates, arc traveling). A numerically efficient and accurate electrical model at the breaker terminals is proposed. Its behavior is shown by comparing simulations with short-circuit experiments. Applications are at system level, including simulation of networks with several breakers, such as multiphase switching transients, selectivity, and coordination with fuses, other breakers and surge protection devices.

Modular Multilevel Converters: State of the Art and Future Progress

Modular multilevel converters (MMCs) have paved the way for power electronics in very demanding application areas. While becoming the worldwide standard for high-voltage dc (HVDC), many other future applications are emerging. More and more, the functionality and cost of power electronics must be judged from a superordinate system view. Passive components around the converter, such as mechanical switchgear, fuses, overvoltage surge suppressors, and filters offer very low potential for future progress. With respect to protection, the scope must be widened from the semiconductors to the protection of the associated equipment (e.g., motors, drive trains, power net, and so on).

Coordination of surge protective devices in low voltage AC power installations

The surges protection in low-voltage AC power circuits is commonly realized by Surge Protective Devices (SPDs). These devices divert a large amount of the surge energy to the ground and reduce the surge voltage to the level acceptable for protected device(s). Adequate protection performances are provided by applying multiple-stage protection assuming cascade deployment of SPDs starting from distribution board toward equipment in an installation. Therefore, SPDs coordination, (i.e. selection of SPDs parameters as well as determination of necessary distance between stages) becomes of great importance and the paper deals with this issue. The proper SPDs coordination is significant for both protected equipment and SPDs themselves (their survival during surges). The paper provides an analysis of the SPDs coordination for case of two-stage protection system. The influence of different lengths of cables between protection stages, as well as influence of type and parameters of load on SPDs protection characteristics have been analyzed and discussed with the purpose of determination of requirements for proper surge protection and coordination of applied SPDs.

MOV Failure Modes and Microstructural Characteristics Under Operating Duty Tests With Multiwaveform Multipulse Currents

Low-voltage (LV) metal oxide varistor (MOV) is the main voltage limiting element employed in surge protective devices to protect sensitive equipment against lightning currents. MOV failures may threaten the security of electrical and electronic systems. In order to investigate the MOV failure modes under lightning strokes more realistically, operating duty tests with multiwaveform multipulse currents (indicated as “MODT”) are carried out on LV MOVs under simulated operating circumstances. To understand the mechanisms of MOV failure, microstructural examinations, including the elemental composition and phase constituent, are conducted on the tested samples with different failure modes. Experimental results show that the main failure modes for LV MOVs under MODT include coating crack, puncture, and cracking. The multiwaveform multipulse currents with larger amplitudes, shorter interpulse time, as well as when the subsequent steep currents occur before the intermediate stroke current, will result in more serious degradation on MOVs. The microstructural examinations on punctured MOVs show that the white intergranular layers become thicker, and the intergranular phase coats the zinc oxide (ZnO) grains. In addition, the decrease of ZnO grain size is observed both on the punctured and fractured MOV surfaces. Based on these microstructural characteristics, the mechanisms of different MOV failure modes are discussed.

배전선로 주상변압기 뇌서지 보호시스템의 신뢰성 향상 및 경제적 구축방안 제안

Recent dramatic climate change requires stronger responses since damages from lightning are increasing although countermeasures for the lightning damages in the operation of the power system have long been a challenge. In this paper, the effect of the lightning surge on the distribution system and the importance of the lightning protection system are examined first. Then, lightning surge voltage limit, protection method of pillar transformer from lightning surge, main causes of failure and life span reduction of pillar transformer, devices for lightning surge protection and its operation are investigated. The effect of lightning surge is analyzed and it was identified that the difference of the lead wire length of the surge arrester makes great difference, which leads to a proposal of effective way of lightning surge protection. The proposed cutout switch with a surge arrester for pillar transformer is capable of simultaneously implementing the surge protection function and the overrun protection function. This new switch will contribute to economic, industrial and technological benefits such as reduced connection points and simplification of the installation, reducing potential causes of failure and lowering installation costs.

Development issues of catenary surge protection system based on a varistor surge arresters

The article presents na issue of determinating an optimal distance between varistors located on 3 kV DC catenary. Line attenuation as a function of distance has been determined during preliminary tests for the following measurement configurations: catenary network unloaded (open), catenary network charged by a value of resistance close to the value of wave impedance of the catenary network test section, catenary network charged by a low voltage varistor. The results allowed to estimate the optimal distance between the varistors and they were verified on the catenary network on Żmigród Test Ring using a surge generator with an amplitude of about 15 kV and varistors designed to work in railway enviroment. The methodology and results of these studies were presented and analyzed in this paper.

Surge protection design with surge-to-digital converter for microelectronic circuits and systems

A surge protection design with surge-to-digital converter is proposed to provide the surge protection for microelectronic products with more flexible applications. The proposed surge-to-digital converter can transfer the occurrences of the surge events into digital output codes by classifying the voltage levels of surge events. It can be used to avoid unwanted power-on reset action, redundant power consumption, or unexpected soft errors, achieving the stability improvement of microelectronic systems. With this surge-to-digital converter, a surge protection design against a surge test of 25 V can clamp the peak voltage of VDD from 22.2 V to 5.6 V. The proposed converter has been verified in a 0.18-μm CMOS process.

통신 및 신호 선로용 서지보호기 내 커넥터의 서지내성 특성 연구

In this paper, we investigated the surge immunity of the connector in the surge protective device for communication and signal. Surge immunity of RJ-11 connector used for Ethernet, RJ-45 connector used for telephone network and D-Sub connector used for serial communication has been tested according to KS standard IEC61643-21. The D-Sub connector was confirmed to have no problems in the operating condition under the 10㎸/5 ㎄ surge condition by the C2 category of IEC61643-21. On the other hand, RJ-45 and RJ-11 have been confirmed that the connectors are broken if it is applied several times or more. Therefore, based on the experimental results of this study, we proposed a reasonable surge capacity for surge protective device for communication and signal.

Electrical properties of ZnO varistor ceramics modified by rare earth-yttrium and gallium dopants

Scanning electron microscopy, electric field-current density measurements, capacitance-voltage testing, X-ray diffraction analysis, and energy dispersive X-ray spectroscopy were performed to study the effects of rare earth-yttrium and gallium doping on the microstructure and electrical properties of ZnO varistors. Our results indicated that the introduction of gallium and yttrium strengthened the barrier height of grain boundaries and led to a decrease in the grain resistance. Both the voltage gradient and nonlinear coefficient of the samples increased and then decreased as the gallium doping level was increased at a given rare earth-yttrium. The residual voltage ratio and the leakage current varied with the opposite relationship. The findings of this study could help to improve the protective effects of surge protection devices assembled from ZnO ceramic varistors and enhance the stability of power systems.

Risk Analysis of Lightning and Surge Protection Devices for Power Energy Structures

This paper studies the risk data and protection measurements of lightning based on the IEC62305 standard. In addition, Visual Basic (VB) is used to build a lightning risk calculation program with a Graphical User Interface (GUI). The data structure, including environment data, line data, zone data, economic data, and protection measures is designed to simulate risk of loss of human life (R1) and risk of loss of economic value (R4). To achieve the most economical protection structure design, additional protection measurements and annual savings are considered. In the practical application, the main purpose is to discuss effective protection distances of surge protective devices (SPDs) for low-voltage power distribution. This paper takes advantage of Electromagnetic Transients Program (EMTP) to simulate the voltage of equipment with different types of loads and length of the cable. After using the protection measures, the value of risk of human life reduces form 21.299 × 10−5 to 0.439 × 10−5 and the value of risk of economic value reduces from 2696.754 × 10−5 to 98.062 × 10−5. The results mean that the protection measures let the values of the risk below the tolerance. By considering the annual cost saving. Assume the cost of protection measures, the interest rate, the depreciation rate, and the maintenance rate are 150,000 $, 4%, 5%, and 1%, respectively. The annual cost before using protective measures, the annual cost after using protective measures, the annual cost of protective measures, and the annual cost saving are $925,000, $33,635, $15,000 and $876,365, respectively. Consequently, it is feasible that the simulation result can provide users with great suggestions to choose the best installation location and achieve the most effective protection design.

A Novel Approach for Maximum Plasma Pressure Estimation at Surge Current Based on Experimental Investigations

This paper introduces a novel approach for estimation of the maximum pressure caused by surge currents in narrow gaps. The new approach was developed based on different experimental tests in the laboratory for surge currents formed as an 8/20- $\mu \text{s}$ impulse. In addition, a clear identification of the dependences of the plasma pressure on different parameters such as the input power and the geometry of the narrow gap was investigated. The validity of the proposed approach was tested using measured and calculated maximum pressure of a different spark gap. The results show that the new technique is simple and efficient for estimating the maximum plasma pressure for similar spark gaps. The estimated pressure can be used in two different ways. It can be used in further investigations to design the sensor system, and on the other hand, it is useful in the development of new surge protective devices to design the geometry of the spark gap and housing. These devices protect electrical devices in the system from an outage caused by overvoltage.

A novel economical grain boundary engineered ultra-high performance ZnO varistor with lesser dopants

A varistor having ultra-high performance was developed from doped ZnO nanopowders using a novel composition consisting of only three (Bi, Ca and Co oxides) dopants. Improved varistor properties were obtained (breakdown field (Eb) 27.5 ± 5 kVcm−1, coefficient of nonlinearity (α) 72 ± 3 and leakage current density (Lc) 1.5 ± 0.06 μAcm−2) which are attributed to the small grain size and grain boundary engineering by phases such as Ca4Bi6O13 and Ca0.89Bi3.11O5.56 along with Co+2 doping in the ZnO lattice. Complex impedance data indicated three relaxations at 25 °C and two relaxations at high temperature (>100 °C). The complex impedance data were fitted into two parallel RC model to extract electrical properties. Two stages of activation energy for DC conductivity were observed in these varistor samples where region I (<150 °C) is found to be due to shallow traps and region II (<225 °C) is due to deep traps. The novel composition is useful for commercial exploitation in wide range of surge protection applications.

Surge Detection Approach for Magnetically Suspended Centrifugal Compressors Using Adaptive Frequency Estimator

The active surge suppression is a challenging topic in the industrial compressor systems. This paper addresses the two issues on the surge detection approach for magnetically suspended centrifugal compressors (MSCCs) utilizing the signal monitoring capabilities of magnetic bearings. An adaptive frequency estimator is proposed to extract the surge signal, and a judgment criterion is establish to the surge state. First, the derivation of a surge disturbance transfer model for the fluctuating pressure and rotor displacement was presented, and the characteristics of surge signal in the MSCC system is analyzed. Then, a conventional notch filter (NF) is used to eliminate the synchronous disturbance in the surge signal, and a modified adaptive notch filter (ANF) method is used to estimate the frequency of surge signal. The convergence analysis of the modified ANF shows that the linearized system is asymptotically stable. The mild surge detection technology and judgement criterion are also discussed. Experimental results on both the 100 kW and 315 kW MSCC systems show that the proposed method can rapidly detect the surge before the MSCC systems develops into the modified surge.

Reduction method of residual voltage by connecting lead length of surge protection device

Background/Objectives: In order to minimize the damage and malfunction of the equipment and system from various surges, we studied the method of reducing the residual voltage according to the lead wire length of the surge protector.Methods/Statistical analysis: In buildings, SPD installation space is insufficient or narrow, resulting in longer lead wire of SPD, and SPD protection performance is decreased due to increase of voltage protection level and residual voltage. In this study, the voltage protection level and the residual voltage of the conventional SPD model and the proposed SPD model are analyzed according to the change of the connecting conductor length from 0.5to 100m.Findings: In the case of the conventional SPD model, the protection level of the SPD is excellent by measuring the voltage protection level at 1,410V even if the lead wire length of the connecting conductor is changed to 10m, but when it exceeds 10m, the protection performance and the protection cooperation are reduced. On the other hand, in the case of the proposed SPD model, the voltage protection level was measured to be 50 V or less even if the lead wire length of the connecting conductor was changed to100 m. Therefore, it is considered that SPD protection performance and protection cooperation are excellent.Improvements/Applications: The design technique of SPD obtained through this study will help to select the optimal installation site and reduce the budget.

Observation of Residual Voltage in Low-Voltage Surge Protective Devices Due to Nearby M-Components

This paper presents experimental results obtained from the Guangdong comprehensive observation experiment on lightning discharge during summer 2014. Residual voltages and current flows in a surge protective device (SPD) connected to an overhead distribution line were observed due to nearby M-components of a triggered lightning flash. Residual voltages with varying characteristics caused by different M-components are analyzed at two terminals of the SPD, and corresponding formation mechanisms for the different characteristics are also discussed. Our results show that the residual voltages at two terminals of the SPD caused by three types of M-component are determined from both the line induction and the ground potential rise (GPR) in a nearby triggered lightning at 40 m distance. The M-component with a large peak current would produce large surge energies in the power line. Under a given peak current, the M-component has greater surge energy than the return stroke. The ground terminal of the SPD is still affected by the GPR, and our results also show that the continuing current superimposed with M-components is an important factor in determining the magnitude of line coupling in power distribution lines when a lightning flash occurs nearby.