Alternating-current Circuits Research Articles

Relay demonstration on board for final year student

The present invention relates to a relay demonstration board, characterized by a microcontroller, numbers of relays are connected to the microcontroller by a plurality of switches, wherein the first relay is connected to a light bulb for controlling the lighting of the bulb and the second and third relay are connected to a DC motor for controlling the rotational direction of the motor. Accordingly, these objectives may be achieved by following the teachings of the present invention. This invention relates to a relay demonstration board for teaching and learning purpose. An electrical relay is an electromagnetic switch operated by a relatively small electric current that can control a much bigger current and thus enable both circuits to be electrically isolated from each other. Relays have been used in wide variety of applications such as home appliances, digital computers and automation system due to its simplicity, long life and high reliability. The project present invention relates to a relay demonstration board. It is developed to allow students to understand the function of relay and how to connect relay in circuit. The major components include three relays, one light bulb and one direct current (DC) motor. The relays are used for control purpose while the light bulb and DC motor are used as the output. Furthermore, the light can be connected in alternating current (AC) or DC circuit to show students how to connect AC circuit and DC circuit. Besides, this tool are invention can be connected to an external microcontroller such as an Arduino board to provide input and or signal to the circuit.

IMPLEMENTASI TEOREMA PHYTAGORAS DALAM PENYELESAIAN SOAL RANGKAIAN AC UNTUK MENINGKATKAN HASIL TES SISWA SMA

Alternating current circuits are one of the physics taught in senior high school. Alternating current (AC) circuits are material related to mathematical equations so that to study this material students must have good mathematical abilities. This research will discuss the improvement of test results for AC circuit material, especially in the RL series, RC series, and RLC series using an alternative method in the form of the Pythagorean theorem on the impedance and voltage equations. This is because the Pythagorean theorem has a mathematical equation that is identical to the impedance and voltage equations in AC circuits. This research was conducted at SMAN 2 Jember using two classes, namely XII MIPA 5 and XII MIPA 7 classes. Based on the research that has been done, the result is an increase in test results in class XII MIPA 5 of 0.54 in the medium category and an increase in test results in class XII MIPA 7 of 0.30 in the medium category. Therefore student responses indicate that the Pythagorean theorem can attract students' interest, provide motivation with positive student responses and students are satisfied in applying it in solving AC circuit problems.

Development and Delivery of an Electric Circuits Course Featuring Competency Based Assessment for First Year Engineering

Most common-core first year engineering programs in Canada include an introduction to electric circuits and electromagnetic physics. The launch of the RE-ENGINEERED first year program at the University of Saskatchewan has provided an opportunity to try something different in this arena. The RE-ENGINEERED program includes a “spine” of electric circuit analysis and the related physics that runs through both semesters of the first year.
 The modular and highly integrated structure of the RE-ENGINEERED program has allowed for accelerated courses that take advantage of timely learning in other courses. In the fall term, students are introduced to direct-current, resistive circuit analysis in a six-week, fifteen-contact-hour module. In the winter term, they experience an accelerated physics course which covers the electricity, magnetism, capacitance, and inductance concepts often taught in tandem with basic circuit analysis. The students then finish the winter term with an intensive course on alternating-current circuit analysis.
 The fall term course fully adopts the competency based assessment system of the RE-ENGINEERED program, and uses in-house-developed quizzes and tutorials on the most basic concepts and calculations to scaffold students to solving more complex circuit analysis problems. The course forgoes a hands-on lab component and focuses on circuit simulation using an open-source simulation package. Concurrent math and MATLAB courses introduce required linear algebra concepts just in time for use in the circuit analysis problems.
 This paper describes the development and delivery of the fall term course, including how the learning outcomes were synthesized and then used as the basis for the development of all other aspects of the course to ensure constructive alignment. Instructor and student impressions of the first delivery of the course are presented along how lessons learned will be applied to modify the course for future offerings.

A REVIEW PAPER ON DESIGN OF COOLING SYSTEM FOR ELECTRICAL TRANSFORMERS, CIRCUIT BREAKERS USED IN TRANSMISSION STATION

Transformer is a device that transfers electric energy from one alternating-current circuit to one or more circuits, either increasing (stepping up) or reducing (stepping down) the voltage. Transformer plays a key role in the power transmission, during this power transmission heat is generated. Cooling of a transformer is the dissipation of heat developed in the transformer to the surroundings. The losses occurring in the transformer are converted into heat which increases the temperature of the windings and the core. In order to dissipate the heat generated cooling should be used. A circuit breaker is an electrical switch that turns off automatically during an overload or short circuit. These switches are important because they protect your electrical components from overheating and breaking. By using different cooling methods we design an cooling system for the transformer and circuit breaker by using Revit software. By using this method, the temperature of transformer and circuit breakers can be reduced in short time. According to generally adopted estimate states that if a transformer’s maximum operating temperature is reduced by 6°C-10°C. The main purpose of the experiment is to improve the cooling system of transformer, to increase the life expectancy of transformer.

Geometric Algebra for teaching AC Circuit Theory

SummaryThis paper presents and discusses the usage of Geometric Algebra (GA) for the analysis of electrical alternating current (AC) circuits. The potential benefits of this novel approach are highlighted in the study of linear and nonlinear circuits with sinusoidal and non‐sinusoidal sources in the frequency domain, which are important issues in electrical engineering undergraduate courses. The analysis and understanding of how AC circuits operate in steady state are of a paramount importance for all the electrical engineers and practitioners around the world. Typically, lecturers of most undergraduate courses teach circuit theory using complex phasors, vector calculus, or linear algebra. However, these approaches have some important limitations in practice, which requires the development of strategies to improve teaching‐learning process related to AC circuit analysis. By formulating a new mathematical framework, the paper presents and discusses how GA can be of help in this approach. It is also described how the results obtained by using GA are validated using computer‐based simulations. It is highlighted how the proposed teaching methodology based on GA theory can be effective in helping students learn AC circuit analysis since it has several potential benefits derived from its simplicity, compactness, and use of easily identifiable geometrical concepts.

Assessment of Impact of AC Circuit Attributes to Outage Frequency in the WECC System

This paper develops a statistics-based approach for analysis of transmission outage data. The method is applied to the Western Electricity Coordinating Council (WECC) transmission inventory and outage data collected and submitted by member utilities to the North American Electric Reliability Corporation's (NERC) Transmission Availability Data System (TADS). The developed model considers the random nature of Alternating Current (AC) circuit outages and introduces fourteen inventory attributes of the AC circuits as explanatory variables for the outage frequency. The main goal of the paper is to investigate statistical relationships between the number of automatic outages on AC circuits and AC circuit inventory attributes based on the TADS data from 2013–2018, which has proven to be sufficient in obtaining statistically valid results. Concepts associated with the statistical validation of performance indices are discussed with emphasis placed on analysis of distinct types of explanatory variables such as voltage class, mileage, number of terminals, circuits per structure, terrain, elevation, etc.

Student profile multiple representations skills under the implementation of OBSIM (observation and simulation) model of teaching in improving creative thinking skills

The research aims to explore multiple representations under the implementation of the OBSIM model of teaching in the alternating-current circuit course. This research compares the modern class (experimental class) and traditional class with the traditional teaching style. Experiment class applies the OBSIM model of teaching, and Traditional Classroom teaches in traditional style with a direct explanation. Computer simulation also integrated into this research by using Matlab Sofware as part of multiple representations, namely programming representation. This research used triangulation methods. The quantitative methods were applied to analyze student achievement tests according to Creative thinking criteria. The Qualitative method was applied using observation of student activity. Student achievement test followed by a pretest, and post-test quasi-experimental research. The data analysis form pretest and postest analysis indicates a significant value of 0.012 (p ≤ 0.05). Thus, it is a significant value, and the average of student activity in experimental class better than control class. The findings conclude that two classes have differences in terms of student multiple representations and creative thinking skills after implementation of OBSIM model of teaching.

The Effectiveness of STEM Education for Overcoming Students’ Misconceptions in High School Physics: Engineering Viewpoint

In the present study, an experimental teaching material using a soundcard oscilloscope developed for science, technology, engineering, and mathematics (STEM) education considering the engineering viewpoint was applied to address student’s misconceptions in the alternating current (AC) circuit topic in high school physics. Four experiments were conducted, and 13 conceptual understanding questions were used to explore the concept of the AC circuit among 192 secondary school students in Indonesia. This study concluded that the STEM system used in this study was considered to be useful to overcome the various misconceptions in high school physics. As a result of this study, it is recommended that more researchers should find, create, develop, and implement more teaching materials that support the understanding of students in AC circuits as well as the other parts of physics. Deeper investigations into the pre-conceptions of students would be another area of research that this study identified as an area of the focus needed in investigating cases of misconceptions.

Analysis and Experiment of a Micro-Loss Multi-Port Hybrid DCCB for MVDC Distribution System

Medium voltage direct current (MVdc) distribution system has numerous advantages over medium voltage alternative current distribution system. However, two shortcomings of the existing hybrid direct current circuit breaker (DCCB) with load current switch, including high construction cost and high operating losses, have constrained the application of existing hybrid DCCBs in MVdc distribution system. To overcome these two shortcomings, a novel multi-port hybrid DCCB with negative voltage source (NVS) has been proposed in this paper. First, the general topology and working principle of the multi-port hybrid DCCB with NVS are presented. Then, focused on the current commutation method and economic performance, comparisons between different hybrid DCCBs have been carried out. The analysis shows that by using multi-port hybrid DCCB with NVS, the construction cost could be reduced dramatically and the operating losses could be reduced to be comparable with alternative current circuit breaker, which are negligible. In the end, to fill the blank of experimental research, based on the topology of multi-port hybrid DCCB with NVS, a prototype with rating voltage of 2 kV has been established, and the test result have verified the multi-port hybrid DCCB with NVS.

Direct / Reverse Analogy between Mechanical System and RLC Series / Paralel Alternative Current Circuits - AC

Abstract There is a direct analogy between the mechanical and electrical phenomena related to vibrations and electromagnetic oscillations in the RLC series AC circuits and an inverse analogy to the electromagnetic oscillations in the RLC parallel alternative current (AC) circuits. Direct analogy RLC series AC circuit refers to the connection between complex velocity and complex electrical intensity, mechanical impedance and electrical impedance, etc. Reverse analogy RLC parallel AC circuits refers to the connection between complex velocity and complex electrical voltage, mechanical impedance and electrical admission, etc.

Comparative methods to assess harmonic response of nonlinear piezoelectric energy harvesters interfaced with AC and DC circuits

Nonlinear piezoelectric energy harvester (PEH) has been widely investigated during the past few years. Among the majority of these researches, a pure resistive load is used to evaluate power output. To power conventional electronics in practical application, the alternating current (AC) generated by nonlinear PEH needs to be transformed into a direct current (DC) and rectifying circuits are required to interface the device and electronic load. This paper aims at exploring the critical influences of AC and DC interface circuits on nonlinear PEH. As a representative nonlinear PEH, we fabricate and evaluate a monostable PEH in terms of generated power and useful operating bandwidth when it is connected to AC and DC interface circuits. Firstly, the harmonic balance analysis and equivalent circuit representation method are utilized to tackle the modeling of nonlinear energy harvesters connected to AC and DC interface circuits. The performances of the monostable PEH connected to these interface circuits are then analyzed and compared, focusing on the influences of the varying load, excitation and electromechanical coupling strength on the nonlinear dynamics, bandwidth and harvested power. Subsequently, the behaviors of the monostable PEH with AC and DC interface circuits are verified by experiment. Results indicate that both AC and DC interface circuits have a peculiar influence on the power peak shifting and operational bandwidth of the monostable PEH, which is quite different from that on the linear PEH.

Equivalent circuit model for the strain sensing characteristics of multi-walled carbon nanotube/polyvinylidene fluoride films in alternating current circuit

In this study, multi-walled carbon nanotube/polyvinylidene fluoride (MWCNT/PVDF) composite films fabricated by solution casting method were used to make composite sensors for large strain measurement. The strain sensing characteristics of the sensors in direct current (DC) and alternating current (AC) circuits were both investigated through experiment. It is observed that the piezoresistivity of the MWCNT/PVDF composite films in DC circuits can be used for strain sensing, but this type of application may be limited since the strain-resistance relationship of the films is highly nonlinear. On the other hand, in AC circuits, the change rate of the dielectric loss tangent (DLT) of the composite is also sensitive to the strain. Besides, the experimental results show that the dependence between the strain and the DLT change rate becomes linear if the MWCNT content and the AC frequency are chosen properly. In this work, an equivalent RLC circuit model of the MWCNT/PVDF composite was proposed to interpret the findings obtained from the experiment. The good agreement between the analytical results and the measurements indicates that the current research reveals a new mechanism for the design of high-performance strain sensors.

Optimization and performance comparison for galloping-based piezoelectric energy harvesters with alternating-current and direct-current interface circuits

Galloping-based piezoelectric energy harvesters scavenge small-scale wind energy and convert it into electrical energy. For piezoelectric energy harvesting with the same vibrational source (galloping) but different (alternating-current (AC) and direct-current (DC)) interfaces, general analytical solutions of the electromechanical coupled distributed parameter model are proposed. Galloping is theoretically proven to appear when the linear aerodynamic negative damping overcomes the electrical damping and mechanical damping. The harvested power is demonstrated as being done by the electrical damping force. Via tuning the load resistance to its optimal value for optimal or maximal electrical damping, the harvested power of the given structure with the AC/DC interface is maximized. The optimal load resistances and the corresponding performances of such two systems are compared. The optimal electrical damping are the same but with different optimal load resistances for the systems with the AC and DC interfaces. At small wind speeds where the optimal electrical damping can be realized by only tuning the load resistance, the performances of such two energy harvesting systems, including the minimal onset speeds to galloping, maximal harvested powers and corresponding tip displacements are almost the same. Smaller maximal electrical damping with larger optimal load resistance is found for the harvester with the DC interface when compared to those for the harvester with the AC interface. At large wind speeds when the maximal electrical damping rather than the optimal electrical damping can be reached by tuning the load resistance alone, the harvester with the AC interface circuit is recommended for a higher maximal harvested power with a smaller tip displacement. This study provides a method using the general electrical damping to connect and compare the performances of piezoelectric energy harvesters with same excitation source but different interfaces.

Investigation into Limitation of Arc Erosion in LV Switches Through Application of Hybrid Switching

In this paper, measurement results of the arc erosion limitation in low voltage (LV) switches are presented. The reduction of the arc erosion in the analyzed electromechanical switches was achieved through an application of the hybrid switching in the tested alternative current circuit during interruption of the inductive current. The presented method is based on a commutation of the current during its interruption into a semiconductor branch that is connected in parallel to the operated switch. Thus, this approach is able to limit the electric arc energy efficiently, and as a consequence the arc erosion of the electrical contacts is also significantly reduced. For this reason, the application of the hybrid switching has a positive influence on a lifespan and a reliability of the operated switch. In order to evaluate the influence of the hybrid switching application on an effectiveness of the limitation of the arc erosion in the analyzed LV switches, 50 000 current interruptions were conducted in the tested circuit by each of four analyzed switches. Researches were performed for two standalone switches during a standard current interruption, as well as, for two switches with applied the hybrid switching system. In order to compare the arc erosion of the contact surfaces in both considered cases, scanning electron microscope method coupled with energy dispersion spectroscopy was applied. Moreover, photos of the electric contact surfaces are presented. Additionally, frames registered by high-speed camera during current interruption are presented for both considered approaches.

Suppression of Leakage Current and Distortion in Variable Capacitance Devices and their Application to AC Power Regulators

The quantity of alternating current (AC) leakage and the value of distortion factor in capacitor currents are discussed with regard to a new power component called variable capacitance device (VCD). This component has terminals for controlling its capacitance. Nonlinear dielectric characteristics are utilized in this device to vary the capacitance. When VCD operates in an AC circuit, the AC leakage from this device through direct current (DC) control voltage source increases according to the conditions of DC control voltage and so on. To solve this problem, we propose techniques for suppressing AC leakage. Although VCD has strong nonlinear characteristics, the current through the capacitor is not distorted significantly. The relations between AC leakage and the distortion in current waveforms are investigated. An application example for an AC power regulator is also introduced to evaluate the distortion in waveforms.

An Electricity Primer for Energy Economists: Basic EE to LMP Calculation

This manuscript provides a technical primer for the energy economist wishing to study the optimal power flow problem and locational marginal pricing (LMPP), but, who like this paper's author, finds it difficult to simply plow through Schweppe et al. (1988). This work aims to provide the reader with sucient technical background to calculate power transfer distribution factors (PTDFs, or network shift factors) for a more complicated model than the simple 3-node model common to energy economics studies. The point of departure for this work is basic electrical engineering fundamentals. We start off Section 1.2 with a simple direct current (DC) circuit analysis, demonstrating Ohms law and Kirchhoffs laws. As these are captured by very basic equations, we quickly move on to alternating current (AC) analysis. Here, we spend quite a bit of effort manipulating fairly straightforward (i.e. sinusoidal) AC voltage equations to derive equations for average voltage, current, and power in an AC circuit. We delve next into phase angles, showing how electrical components such as inductors and capacitors bring voltage and current out of phase. We then demonstrate both graphically and algebraically the effect of non-zero phase angles on resistance and power relations in an AC circuit. The goal of Section 1.2 is to familiarize the reader with concepts that economists and operations researchers generally take for granted, but are quite foreign to those of us who are self-taught.

An Electricity Transmission Primer for Energy Economists: Parts 1 and 2

This paper provides a technical primer for the energy economist wishing to study the optimal power flow problem, but, who like this paper’s author, find it difficult to simply plow through Schweppe et al. (1988). This paper’s aim is to provide the reader with sufficient technical background sufficient to calculate power transfer distribution factors (PTDF’s, or network shift factors) for a more complicated model than the simple 3-node model common to energy economics studies. The point of departure for this work is basic electrical engineering fundamentals. We start off Section 2 with a simple direct current (DC) circuit analysis, demonstrating Ohm’s law, and Kirchhoff’s laws. As these are captured by very basic equations, we quickly move on to alternating current (AC) analysis. Here, we spend quite a bit of effort manipulating fairly straightforward (i.e. sinusoidal) AC voltage equations to derive equations for average voltage, current, and power in an AC circuit. From there, we delve into the concept of “phase angles,” showing how electrical components such as inductors and capacitors bring voltage and current “out of phase.” We then demonstrate both graphically and algebraically the effect of non-zero phase angles on resistance and power relations in an AC circuit. The goal of section 2 is to familiarize the reader with concepts that economists and operations researchers generally take for granted, but are quite foreign to those of us who are self-taught.

An AC/C Network Primer for Energy Economists: Part 1: Basic EE and PTDFS

This is the first of a two-part series (given sufficient interest) of papers providing a technical primer for the energy economist wishing to study the optimal power flow problem, but, who like this paper’s author, find it difficult to simply plow through Schweppe et al. (1988). This paper’s aim is to provide the reader with sufficient technical background sufficient to calculate power transfer distribution factors (PTDF’s, or network shift factors) for a more complicated model than the simple 3-node model common to energy economics studies. The point of departure for this work is basic electrical engineering fundamentals. We start off Section 2 with a simple direct current (DC) circuit analysis, demonstrating Ohm’s law, and Kirchhoff’s laws. As these are captured by very basic equations, we quickly move on to alternating current (AC) analysis. Here, we spend quite a bit of effort manipulating fairly straightforward (i.e. sinusoidal) AC voltage equations to derive equations for average voltage, current, and power in an AC circuit. From there, we delve into the concept of “phase angles,” showing how electrical components such as inductors and capacitors bring voltage and current “out of phase.” We then demonstrate both graphically and algebraically the effect of non-zero phase angles on resistance and power relations in an AC circuit. The goal of section 2 is to familiarize the reader with concepts that economists and operations researchers generally take for granted, but are quite foreign to those of us who are self-taught.

A Molecular Half-Wave Rectifier

This paper describes the performance of junctions based on self-assembled monolayers (SAMs) as the functional element of a half-wave rectifier (a simple circuit that converts, or rectifies, an alternating current (AC) signal to a direct current (DC) signal). Junctions with SAMs of 11-(ferrocenyl)-1-undecanethiol or 11-(biferrocenyl)-1-undecanethiol on ultraflat, template-stripped Ag (Ag(TS)) bottom electrodes, and contacted by top electrodes of eutectic indium-gallium (EGaIn), rectified AC signals, while similar junctions based on SAMs of 1-undecanethiol-SAMs lacking the ferrocenyl terminal group-did not. SAMs in these AC circuits (operating at 50 Hz) remain stable over a larger window of applied bias than in DC circuits. AC measurements, therefore, can investigate charge transport in SAM-based junctions at magnitudes of bias inaccessible to DC measurements. For junctions with SAMs of alkanethiols, combining the results from AC and DC measurements identifies two regimes of bias with different mechanisms of charge transport: (i) low bias (|V| < 1.3 V), at which direct tunneling dominates, and (ii) high bias (|V| > 1.3 V), at which Fowler-Nordheim (FN) tunneling dominates. For junctions with SAMs terminated by Fc moieties, the transition to FN tunneling occurs at |V| ≈ 2.0 V. Furthermore, at sufficient forward bias (V > 0.5 V), hopping makes a significant contribution to charge transport and occurs in series with direct tunneling (V ≲ 2.0 V) until FN tunneling activates (V ≳ 2.0 V). Thus, for Fc-terminated SAMs at forward bias, three regimes are apparent: (i) direct tunneling (V = 0-0.5 V), (ii) hopping plus direct tunneling (V ≈ 0.5-2.0 V), and (iii) FN tunneling (V ≳ 2.0 V). Since hopping does not occur at reverse bias, only two regimes are present over the measured range of reverse bias. This difference in the mechanisms of charge transport at forward and reverse bias for junctions with Fc moieties resulted in large rectification ratios (R > 100) and enabled half-wave rectification.

An integrated methodology to predict the likelihood of spurious actuation of AC circuits due to fires in commercial nuclear power plants

Research efforts by the nuclear power industry and, most recently, its regulatory agency, the U.S. Nuclear Regulatory Commission (USNRC), have provided information useful for risk-informed analysis of the effects of spurious actuation (“hot shorting”) of alternating current (AC) electrical circuits at nuclear power plants. The results from these efforts have been integrated into a methodology to predict the likelihood of spurious actuation of AC circuits due to fires in commercial nuclear power plants.