Investigation of surge propagation in transient voltage surge suppressors and experimental verification

An on-going question in the field of surge protection study is how to predict incipient failure of power electronics in the event of a short time, high voltage, and high energy transient surge propagation. The work presented in this thesis addresses the above question by investigating how a high voltage transient surge, whose duration is in the microseconds range, will propagate through the two-level transient voltage suppressor system that is intended to protect sophisticated electronics situated close to the service entrance of a building. In this work the energy patterns relevant to the individual components of the system are evaluated using numerical methods and some of the results are also compared with those obtained using SPICE simulations. Although several mathematical models for surge protection components are discussed in the literature and some device specific ones are provided by manufacturers, there is no evidence to show that a complete analysis, using any such model, has been performed to predict the energy absorptions and associated time lags between the components in a TVSS. Numerical simulation techniques using MATLAB are used to estimate the energy absorption and associated time delays in relation to the propagated transient surge, in individual components of a transient voltage surge suppressor. This study develops mathematical models for particular nonlinear transient surge absorbing elements, specifically for the metal oxide varistor and transient voltage suppressor diode, formulates the state equations which are used to numerically simulate several instances of the transient voltage surge suppressor system, and presents simulation results. All results are validated experimentally using a lightning surge simulator. The outcomes established using the two approaches indicate that the theoretical energy calculations are within 10% of the experimental validations for the metal oxide varistor, which is the main energy absorbing element in the system. The remaining energy distributions in the line-filter components and the transient voltage suppressor diode, which are at least 10 times smaller, are all within 20% of the experimental results. The times at which, the metal oxide varistor and the transient voltage suppressor diode switches to heavy conduction mode are also simulated accurately

Overload protection for AC-DC transfer measurement standards

Abstract: Electrical transient overloads (ETOs) are inherent to electrical and electronic systems, especially those that are composed of semiconductor materials. However, as the subject has received research attention since the mid-1900s, design engineers are familiar with this class of electrical or electronic disturbance. Thus, in most electrical and electronic applications, ETOs are compensated for through the implementation of an ETO protection device(s). Nevertheless, more work is still to be done to develop efficient techniques to mitigate this class of disturbance. The work presented in this dissertation identifies the most probable sources of ETOs in the alternating current-direct current (AC-DC) transfer measurement system. The AC-DC transfer measurement system is used to provide electrical calibration services to the national industry and national and regional standardisation bodies, thus complementing the metrological traceability of the international (SI) units of AC current, voltage and power. Thermal converters (TCs), which serve as the main elements of the AC-DC transfer measurement system, are most susceptible to damage and destruction from ETO events, which may arise during the measurement process or be caused by human error. This work also presents a conceptual ETO protection solution for thermal converters, developed through mathematical and simulation analysis...M.Phil. (Electrical and Electronic Engineering

A Circuit Model for ESD Performance Analysis of Printed Circuit Boards

This paper provides a SPICE-compatible circuit model for characterizing electrostatic discharge (ESD) clamping performance of protection devices mounted on printed circuit boards (PCBs). An equivalent circuit model for a commercial ESD generator is introduced and a simulation methodology of an ESD protection device with non-linear resistance characteristic using voltage controlled current source is described. These models combined to create a full circuit model with a PCB model in a SPICE-like circuit simulator. Comparison results between the simulated and measured are presented to verify the accuracy of the proposed circuit model. A trade-off analysis between the ESD clamping performance and signal integrity with the ESD protection device in high-speed applications is also presented as a case study

Correlación entre ondas de ensayo para dispositivos supresores de sobretensiones

There is a varied number of standard impulse waves that are used to test the operation of transient surge suppressor devices. In particular, tests that check the maximum discharge pulse current are of importance. This paper analyzes the relationship between these different forms of impulsive waves, in order to obtain a correlation between them to apply one or the other with similar results. The conclusions reached from a simplified theoretical development are corroborated by laboratory measurement and simulation.Existe un variado número de ondas impulsivas estándar que se utilizan para ensayar el funcionamiento de los dispositivos supresores de sobretensiones transitorias. En particular, resultan de importancia los ensayos que comprueban la corriente máxima de impulso de descarga. Se analiza en este trabajo la relación existente entre estas distintas formas de ondas impulsivas, de forma tal de poder obtener una correlación entre ellas para aplicar una u otra con similares resultados. Las conclusiones que se alcanzan a partir de un desarrollo teórico simplificado son corroboradas mediante medición en laboratorio y simulación

Relay based Coupling Scheme of High Speed Communication data, High voltage DC And High Power Pulsed AC for Coaxial Cable

Coaxial cable telemetry is most commonly used in the field of underwater applications like data logging in oil rigs, underwater wireless modem, underwater acoustic measurements, borehole measurements, deep sea telemetry for sediment analysis, airborne sonars, imaging sonars etc. In all the above applications coaxial multicore cables are used. The design and development of relay based coupling scheme which helps to replace the multi core cable with a single core coaxial cable for telemetry application is described. Single core cable is suitable for long distance data communication. Multi core cables are generally heavy and due to the size, may not meet space constraints in complex systems. They are not economical too. The relay based coupling scheme is used to mix or separate the high speed bi-directional communication data, high voltage DC and high power pulsed AC. In single relay scheme one relay is used to switch the centre core of single core coaxial cable. Here the ground is common for both high power AC transmission and high speed bi-directional data path. A dual relay scheme is discussed where two relays are used to switch both the centre core and ground of the single core coaxial cable. This provides more ground isolation and can avoid ground lifting issues while high power AC transmission occurs. The simulation of the coupling scheme was done using PSpice®. A prototype of the coupling scheme was also made for analysis. Filter responses were analysed for each coupling path. The DC coupling filter has 85 Hz cut-off frequency at -3 dB. The cut-off frequency of high speed data coupler is 500 KHz at -3 dB. A 4.3KV peak to peak of 3 KHz and 7 KHz AC signals were transmitted and measurements were taken to analyse the effect of high voltage over different coupling paths. The 3 KHz signal has a peak of 61.88 dB and that of 7 KHz signal, the peak is 62.50 dB. The signal components of 3 KHz signal in the DC path has a voltage level of 9.375 dB and that of 7 KHz signal is 25.63 dB

Development of DC Circuit Breakers for Medium-Voltage Electrified Transportation

Medium-voltage DC (MVDC) distribution is an enabling technology for the electrification of transportation such as aircraft and shipboard. One main obstacle for DC distribution is the lack of adequate circuit fault protection. The challenges are due to the rapidly rising fault currents and absence of zero crossings in DC systems compared to AC counterparts. Existing DC breaker solutions lack comprehensive consideration of energy efficiency, power density, fault interruption speed, reliability, and implementation cost. In this thesis, two circuit topologies of improved DC circuit breakers are developed: the resonant current source based hybrid DC breaker (RCS-HDCB) and the high temperature superconductor fault current limiter based solid state DC breaker (HTS-FCL-SSDCB). The RCS-HDCB utilizes a controllable resonant current source based upon wide bandgap (WBG) switches that enable low loss and fast fault interruption due to the fast switching speed. The voltage applied by the controllable resonant current source is much lower than the rated voltage of the DC breaker, allowing the utilization of significantly lower voltage rated WBG switches. The conduction path\u27s sole component is a fast-actuating ultra-low resistance vacuum interrupter for high efficiency during normal operation. As the second DC breaker concept, the HTS-FCL-SSDCB is subdivided into a fault current limiter (FCL) and solid state DC breaker (SSDCB). The FCL is based upon a high temperature superconductor cable which has natural fault current limiting capabilities while having negligible insertion losses for normal load currents. The SSDCB utilizes WBG switches to decrease conduction losses compared to Silicon-based breakers. The FCL reduces fault current such that the number of semiconductive switches in the SSDCB is minimized. Both breakers feature a metal-oxide varistor device in parallel to clamp overvoltages and dissipate energy after fault interruption. Modeling, simulation, and analysis in electrical and thermal domains are conducted to verify the functionality of the DC circuit breakers. The simulation results confirm the feasibility of these two DC breakers in their proposed applications of 2.4 kV electric aircraft and 20 kV shipboard MVDC distribution systems

Direct current hybrid breakers : a design and its realization

The use of semiconductors for electric power circuit breakers instead of conventional breakers remains a utopia when designing fault current interrupters for high power networks. The major problems concerning power semiconductor circuit breakers are the excessive heat losses and their sensitivity to transients. However, conventional breakers are capable of dealing with such matters. A combination of the two methods, or so-called ‘hybrid breakers’, would appear to be a solution; however, hybrid breakers use separate parallel branches for conducting the main current and interrupting the short-circuit current. Such breakers are intended for protecting direct current (DC) traction systems. In this thesis hybrid switching techniques for current limitation and purely solidstate current interruption are investigated for DC breakers. This work analyzes the transient behavior of hybrid breakers and compares their operations with conventional breakers and similar solid-state devices in DC systems. Therefore a hybrid breaker was constructed and tested in a specially designed high power test circuit. A vacuum breaker was chosen as the main breaker in the main conducting path; then a commutation path was connected across the vacuum breaker where it provided current limitation and interruption. The commutation path operated only during any current interruption and the process required additional circuits. These included a certain energy storage, overvoltage suppressor and commutation switch. So that when discharging this energy, a controlled counter-current injection could be produced. That countercurrent opposed the main current in the breaker by superposition in order to create a forced currentzero. One-stage and two-stage commutation circuits have been treated extensively. This study project contains both theoretical and experimental investigations. A direct current shortcircuit source was constructed capable of delivering power equivalent to a fault. It supplied a direct voltage of 1kVDC which was rectified having been obtained from a 3-phase 10kV/380V supply. The source was successfully tested to deliver a fault current of 7kA with a time constant of 5ms. The hybrid breaker that was developed could provide protection for 750VDC traction systems. The breaker was equipped with a fault-recognizing circuit based on a current level triggering. An electronic circuit was built for this need and was included in the system. It monitored the system continuously and took action by generating trip signals when a fault was recognized. Interruption was followed by a suitable timing of the fast contact separation in the main breaker and the currentzero creation. An electrodynamically driven mechanism was successfully tested having a dead-time of 300:s to separate the main breaker contacts. Furthermore, a maximum peak current injection of kA at a frequency of 500Hz could be obtained in order to produce an artificial current-zero in the vacuum breaker. A successful current interruption with a prospective value of 5kA was achieved by the hybrid switching technique. In addition, measures were taken to prevent overvoltages. Experimentally, the concept of a hybrid breaker was compared with the functioning of all mechanical (air breaker) and all electronical (IGCT breaker) versions. Although a single stage interrupting method was verified experimentally, two two-stage interrupting methods were analyzed theoretically

Determinación de los requerimientos para la transformación de un generador de impulso de tensión en un generador de impulso de corriente

El presente trabajo de grado presenta el estudio de la determinación de los requerimientos necesarios para transformar el Generador de Impulso de Voltaje de 1100 kV presente en el Laboratorio de Alta Tensión de la Universidad del Valle en un Generador de Impulsos de Corriente que amplíe la oferta de servicios del Laboratorio para realizar pruebas en Dispositivos de Protección contra Sobretensiones o Pararrayos. Para dar cumplimiento al objetivo se plantea una metodología que consiste en la apropiación con el GIV actual mediante estudio y simulación del mismo, y de igual forma con la teoría de funcionamiento del GIC. Se realiza un estudio del modelo circuital de los DPS y de la normatividad que rige la realización de pruebas en el mismo para definir el nivel de practicidad del Generador a implementar, y con estos temas abordados se procede finalmente a determinar los requisitos para transformar el GIV presente en un GIC incluyendo información sobre elementos necesarios que ya se posean y elementos por obtener para formar el circuito de generación de la onda estándar necesaria para llevar a cabo las pruebas mencionadas en los DPSPregradoINGENIERO(A) ELECTRICIST

Time-domain Analysis of Multiconductor Transmission Lines Excited by Transient Electromagnetic Disturbances Based on the Analog Behavior Modeling

L'abstract è presente nell'allegato / the abstract is in the attachmen