Current Protective Devices Research Articles

Combined Wind Turbine Protection System

The increasing deployment of wind turbines in technologically advanced nations underscores the need to enhance their reliability, extend their operational lifespan, and minimize failures. The current protection devices for wind turbine components do not sufficiently shield them from various external factors that degrade performance. This study addresses the environmental and technical challenges that disrupt wind turbine operations and reviews existing research and technical solutions for protecting individual components, supported by experimental findings. Using a decomposition method followed by the integration of protection components, we propose a combined protection system designed to improve the overall resilience of wind turbines. The proposed system aims to reduce incidents, extend service life, and increase reliability, addressing a critical gap in wind energy technology and contributing to its continued development and efficiency.

Research on DC Electric Shock Protection Method Based on Sliding Curvature Accumulation Quantity

To address the limitations of current DC residual current protection methods, which primarily rely on the amplitude of DC residual current for fault detection and fail to safeguard against electric shocks at two points on the same side in DC Isolated Terra (IT) System systems, this paper introduces a novel protection method based on DC electric shock features. This paper first analyzes the sliding curvature accumulation and peak rise time features of DC basic residual current, load mutation current, and animal body electric shock current under multi-factor conditions. The analysis shows that sliding curvature accumulation in the range of 0.1 ≤ K ≤ 1 and a peak rise time of Δt ≥ 20 ms can effectively distinguish animal body electric shock. Then, based on this electric shock’s distinctive characteristics, an approach for identifying types of electric shock is developed. Finally, a DC residual current protective device (DC-RCD) is designed. The prototype test results demonstrate that the DC-RCD has an action time of ts < 70 ms. The proposed method accurately provides protection against electric shocks and effectively addresses the issue of inadequate protection when two fault points occur on the same side within an IT system. This approach holds significant reference value for the development of next-generation DC-RCDs.

Residual current detection method based on improved VMD-BPNN.

To further enhance the residual current detection capability of low-voltage distribution networks, an improved adaptive residual current detection method that combines variational modal decomposition (VMD) and BP neural network (BPNN) is proposed. Firstly, the method employs the envelope entropy as the adaptability function, optimizes the [k, ɑ] combination value of the VMD decomposition using the bacterial foraging-particle swarm algorithm (BFO-PSO), and utilizes the interrelation number R as the classification index with the Least Mean Square Algorithm (LMS) to classify, filter, and extract the effective signal from the decomposed signal. Then, the extracted signals are detected by BPNN, and the training data are utilized to predict the residual current signals. Simulation and experimental data demonstrate that the proposed algorithm exhibits strong robustness and high detection accuracy. With an ambient noise of 10dB, the signal-to-noise ratio is 16.3108dB, the RMSE is 0.4359, and the goodness-of-fit is 0.9627 after processing by the algorithm presented in this paper, which are superior to the Variational Modal Decomposition-Long Short-Term Memory (VMD-LSTM) and Normalized-Least Mean Square (N-LMS) detection methods. The results were also statistically analyzed in conjunction with the Kolmogorov-Smirnov test, which demonstrated significance at the experimental data level, indicating the high accuracy of the algorithms presented in this paper and providing a certain reference for new residual current protection devices for biological body electrocution.

Solar Photovoltaic System Performance Improvement Using a New Fault Identification Technique

Identifying faults in the photovoltaic (PV) arrays is very much essential in improving the PV system’s safety and reliability. Solar PV arrays operate with non-linear characteristics, installed with maximum power point trackers (MPPT’s), and blocking diodes cause mismatch levels. Line-to-line and line-to-ground faults are identified, and the faulted circuits are isolated by means of over current protection devices (OCPD) and ground fault protection devices (GFPD). In order to improve the accuracy of fault detection, artificial intelligence (AI)-based techniques like Fuzzy inference, wavelet, support vector machine, and k-nearest neighbors are used. The drawback of AI-based techniques are (1) requirement of large dataset for effective fault identification and also show incompatibility if there is low irradiation and (2) require a larger number of voltage and current sensors. An experimental setup of 160 W, 4 × 4 solar PV array having PV modules (SPB) is subjected to different fault conditions (CS), and the faults are identified using the minimum number of sensors. The faults that are not detected by the conventional methods are detected using this proposed method, and the power gain due to the fault identification is around 152% which is 97 W in the PV array.

A Study on the Development of ETEC-IGR Test Devices for the Reliability Evaluation of RCD and ETEC-DPS

In this study, ETEC-IGR was developed in order to test the residual current protective device (RCD) and electric fire prevention system (ETEC-DPS) used in low-pressure electrical facilities. Furthermore, the reliability of the developed product was verified with Minitab PGM. The ETEC-IGR was designed to supply single-phase two-wire power and was equipped with an insulation transformer to protect against surge voltages and ground defects during testing. The results revealed that the load current (IL) may linearly flow from 0 A to 50 A, and the leakage current (IG) and the leakage current of the resistance component (IGR) may vary from 0.0 mA to 30 mA. Furthermore, the standby power was 98.43 W when the developed ETEC-IGR and the ETEC-DPS were connected. Moreover, the standby power was analyzed as 97.59 W when only the developed ETEC-IGR was connected. In addition, the standby power of the ETEC-DPS was interpreted as 0.84 W, and it was judged that the characteristics of the developed product were excellent. In addition, the heat dissipation environment, noise level, winding resistance, insulation resistance, voltage fluctuation rate, and AC/DC withstand voltage test of the developed test device met the relevant regulations. The normal distribution analysis of the developed ETEC-IGR revealed that the standard deviation was 0.3209, AD was 0.520, and P was 0.171. Thus, the data were interpreted as appropriate. In addition, the measured data were found to be more than 95% reliable, and the error was also less than 1 W. Furthermore, the reliability was verified with the 95% confidence interval in the box plot and histogram analysis.

Are hearing protection devices used in the workplace really efficient? A systematic review.

The most common current hearing protection devices (HPDs) on the market include earplugs and earmuffs. A variety of materials can be used to manufacture these devices, and each offers a level of noise attenuation that is informed by the manufacturer although it does not always correspond to the attenuation observed in real-world use. To evaluate the noise attenuation of HPDs available to workers exposed to noise. The most relevant studies originally published in English, Portuguese, or Spanish that investigated the noise attenuation effectiveness of HPDs used by workers exposed to noise were analyzed. The following electronic databases were searched by 2 independent reviewers for studies published from 1999 to 2019: MEDLINE (PubMed), Scopus, Web of Science, EMBASE, Cochrane Library (OVID), ProQuest, and BVS-Bireme. Different combinations of the following search terms (MeSH terms) were used for all databases: "Hearing Loss, Noise-Induced", "Ear Protective Devices" (Efficacy OR Effectiveness)", "Noise, Occupational". The search strategy yielded a total of 326 potentially relevant studies. After the removal of duplicates, 156 remained for the screening of titles and abstracts. After reviewing titles and abstracts, 46 studies were selected for full-text reading. Of these, six were included in this systematic review. Hearing protection devices reduced the noise exposure and were effective in all included studies in different countries, types of activity, and sound pressure exposure.

РОЗРОБКА МОДЕЛІ СТРУМОВОГО РЕЛЕЙНОГО ЗАХИСТУ В ПАКЕТІ MATLAB/SIMULINK

Based on MATLAB / SIMULINK, a model of a radial network with one-way power supply and three radial lines with a complex load at the end of each line is built. The model allows you to study the relationship of processes in the network in the case of normal operation, and in the case of possible damage at different distances from the power supply. The proposed model of the current protection device consists of a three-phase current meter, a switching element and a display. In the dialog box of the device, the primary current of the transformer current, the mains voltage frequency, the multiplicity of the protection tripping current and the tripping time multiplier are set, and the type of the standard curve of the protection tripping time characteristic is selected. A protection device with inverse time delay characteristics measures the RMS value of three-phase AC. The switch-off signal is given from the output of the relay protection device, depending on the time delay. The display shows the operating time of the device, primary and secondary currents and setpoint multiplicity. The performance of the device was evaluated by a three-phase short circuit. As a result of research it is established that the offered model of the relay protection device confirms correct behavior of the relay of the maximum current in various operating modes of a network. The behavior of the protection device indicates that the proposed model can be used in further work to develop algorithms for current protection of lines. To improve the model of the device, it is necessary to investigate the influence of simulation parameters, such as data on power sources, power lines, load and type of damage on the parameters of the protection device. The scientific novelty is the the developed models of the electric network and the device of the maximum current protection with all inverse characteristics of endurance of time provided by the ANSI / IEEE and IEC standards. The practical significance of the work is the possibility of using the model to test the selectivity and sensitivity of protection in the event of changes in network parameters in a wide range and in the case of research in the development and improvement of relay protection devices and training.

Low voltage series arc fault identification method based on VMD and RVFL neural network

Abstract In low-voltage distribution system, series arc fault is one of the main causes of fire accidents. The series arc current characteristics of load are similar to its normal working current, and the ordinary current protection device cannot detect it effectively. In this paper, an arc recognition method based on variational modal decomposition (VMD) and random vector functional link (RVFL) neural network is proposed. The series arc current data of different loads are collected by the low-voltage series arc experimental platform, and the arc current characteristics are analyzed. Four different intrinsic mode functions (IMF) are obtained by variational modal decomposition, and their fuzzy entropy is calculated respectively to form an eigenvector data set, which is input into RVFL neural network for training and identification. In this paper, approximate entropy (ApEn), sample entropy (SampEn) and fuzzy entropy (FuzzyEn) are extracted as feature vectors for each IMF of VMD, their discrimination for different loads is analyzed, and the recognition accuracy of RVFL neural network compared with SVM and BP neural network algorithm is compared. It is verified that the arc recognition method proposed in this paper has better recognition effect.

Smart Circuit Breaker

This project is to supply single phase home appliances. This project is used for an alternative for MCB. MCB is fault current protective device which trip on fault current which flows in the circuit. MCB are based on the thermal bimetallic trip mechanism which is very slow and tripping time is based upon percentage of overloads MCB having bimetallic trip which gets derated after some mechanical operation and cause unwanted tripping. All the above faults will be overcome by smart circuit breakers which provide all types of protection such as overload, under voltage, high temperature and short circuit protection, this type of protection is necessary because, now days all, appliance such as LCD, Air conditioner, Refrigerator, etc consist of electronic circuitry which is voltage sensitive and get damage at voltage fluctuation. This project also monitors and display fault on LCD and stores the data for further action. Smart circuit breaker is fast acting and sense relay as fast as possible and trips the relay within 100msec. than MCB which takes 1000msec. to 1600msec. In addition to that LM 35 temperature sensor is also interface to microcontroller by if temperature exceed 550C microcontroller will trip the relay. The intention to use temperature sensor is to detect fire hazard in domestic purpose as well as commercial purpose.

Sustained Coordination of Devices in a Two-Layer Protection Scheme for DGs-Integrated Distribution Network Considering System Dynamics

Distribution networks are usually protected by directional overcurrent relays (DOCRs). Besides, autoreclosers and fuses can be used for protecting lateral feeders to minimize power cuts. Coordinated operation of protection device must be maintained to ensure optimal fault isolation. Typically, steady-state fault current and static protective device characteristics are used to determine optimal settings of devices such that coordinated operation is verified. Sine fault current is not a steady signal and protection devices have dynamic behaviors, the conventionally-determined settings of devices can lead to loss of coordination jeopardizing system reliability. In this paper, a two-layer protection scheme is proposed for a distribution network with distributed generators (DGs). The first layer has DOCRs to protect main feeders. The second has autoreclosers and fuses to protect lateral feeders. Optimal settings of devices are determined to achieve both local-layer and inter-layer coordination of devices by constrained nonlinear optimization. Full dynamic models of every component and transient data of fault current are considered. Furthermore, to sustain coordination under DGs, a hybrid superconducting fault current limiter (HSFCL) with high temperature superconducting resistive element is connected in series to each DG. Dynamic modeling-based HSFCL cost minimization is searched by multi-objective optimization. The approach is applied to two distribution networks and simulation results are analyzed.

Residual Current Detection Method Based on Variational Modal Decomposition and Dynamic Fuzzy Neural Network

To further improve the detection ability of residual current in low-voltage distribution networks, an adaptive residual current detection method based on variational mode decomposition (VMD) and dynamic fuzzy neural network (DFNN) is proposed. First, using the general <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -value selection method of VMD proposed in this study, the residual current signal is decomposed into <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> intrinsic mode functions (IMFs). By introducing the cross-correlation coefficient <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R$ </tex-math></inline-formula> and the time-domain energy entropy ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> as two classification indexes, IMFs are divided into three categories: effective IMFs, noise IMFs and aliasing IMFs. Then, the aliasing IMFs are denoised by recursive least squares (RLS), and the denoised IMFs are superimposed with the effective IMFs to obtain the reconstructed signal. Finally, the dynamic fuzzy neural network (DFNN) is adjusted by the minimum output method to achieve the detection of the reconstructed residual current signal, and the network is used to predict the residual current according to the detection results. The detection results of the simulation and measured data show that the proposed algorithm has high detection accuracy and is superior to the wavelet neural network, empirical mode decomposition-thresholding, and wavelet entropy-auto encoder-back propagation neural network methods in terms of mean square error, goodness of fit and running time. This method provides a reference for further research on new adaptive residual current protection devices.

Fault Clearance Ultra Sensing Electronic Circuit Breaker

As Electrical equipments are more sensible, it has to protect them from high current, short circuit occurance. For tripping, fuse, relays and circuit breakers are employed to safeguard the power system components and circuits as well. Due to existence of sensitive components, much attention is taken to care about the protecting system. This paper explains the protection of equipments using suitable circuit breaker. Ultra fast acting electronic circuit breaker(UFECB) is designed to act as an over current protection device. Circuit breakers like fuse or miniature breakers are preferred for breaking the circuit once short circuit is occurred. In case, when overload fault occurs, the time of tripping is slow and which depends on percentage of overload. For instant fault clearance, tripping mechanism is activated for sensitive loads[1]. Time taken for the tripping mechanism is also considered in a great manner for breaking and making the circuit at short instant.

Research, design, manufacture leakage current protection device for 660V/1140V underground mine electrical networks

This paper presents the results of researching, designing and manufacturing leakage current protection device for 660 V/1140 V ungrounded three-phase electrical networks. The outstanding features of the device are: ability to create wide deformation characteristic; automatically detect and grounded the leakage phase. Device test results show that relay operation time ​​for symmetrical and asymmetric leak resistors are 30 kΩ/60 kΩ per phase and 20 kΩ /50 kΩ for 660 V/1.140 V networks respectively. The total operating time of the device when single phase leaking through a 1 kΩ resistor not exceed 105 ms. The circuit automatically detects and accurately grounded the leakage phase through 100 Ω resistance, the total detection and grounded the leakage phase time does not exceed 110 ms. This research result can be applied in the design and manufacture of high-quality and reliable leakage current protection devices used in underground mines, replacing imported products.

Face Masks and Respirators for the Dental Health Care Provider: A Review

As protocols and standards of personal protective equipment are changing in the time of COVID-19, dental health care providers must brief themselves on the appropriate products to keep them and their staff safe. This article reviews the current respiratory protection devices used to minimize the risk of SARS-CoV-2 infection.

The impact of current transformer saturation on the performance of differential protection of generators and motors at frequencies below 50 Hz

At present, low-frequency modes are widely used in the operation of electric generators and engines. Relay protection should ensure the implementation of its functions even at a frequency below the rated by tens of percent. Signals from current transformers go to inputs of current relay protection devices, and their performance deteriorates significantly at frequencies below industrial. The article experimentally investigates the impact of the core saturation of a current transformer that occurs at low frequency on the value of the differential current in the differential relay protection circuit of a generator or motor. The authors analyze how the burden of current transformers, the value of the current and its frequency affect the value of the differential current. They show the possibility of both a false response and a failure in the operation of the differential protection at low frequency. Moreover, the authors give practical recommendations on ensuring emergency protection of equipment at a frequency below 50 Hz.

Hardware and algorithm of digital protection of electrified railway transport

The paper analyzes current analog protection devices, presents an experiment on the introduction of digital terminals, considers the possibility of improving the efficiency of digital protection system of direct current within traction railroad net-work.

Measures to Minimize Series Faults in Electrical Cords and Extension Cords

In electrical power systems, cords and extension cords are exposed to mechanical damage and other insulation stresses. Mechanical damage to stranded conductors can reduce locally their cross section or break them and cause anomalous local conditions of overheating or arcing. The ordinary protective devices cannot detect the series faults that persist, so the fault point remains energized and is subject to electric shock and fire hazards. Effective protection can be accomplished by implementing active and passive measures: installing arc-fault circuit interrupters or arc-fault detection devices, able to detect arcing faults, or wiring the circuits with a grounding protection conductor to involve the ground in every fault. In this way, residual current protective devices (residual current devices or ground fault protective devices) quickly protect the series faults not only with arc, but also without it. Ground-fault-forced cables facilitate by design the conversion of any kind of cable fault to a ground fault. They are particularly recommended for cords and extension cords, internal circuits to grounded equipment, uninterruptible power system continuity circuits, aircraft circuits, road tunnels, data centers, refrigerated containers parks, residences, and hospitals.

Lightning Strike Risk Assessment and Lightning Protection Approach for Highway Electromechanical Equipment

To ensure the normal operation of highway electromechanical equipment and avoid lightning disasters, it is necessary to design lightning protection devices in the highway electromechanical system. However, due to factors such as the technical level and life limit of the lightning protection device, some lightning protection devices are over-aged, and often fail, resulting in frequent lightning damage to the electromechanical system equipment. In this study, the design and comprehensive evaluation of the current lightning protection devices was carried out to ensure that they can work normally. Safety analysis was performed on the electromechanical system lightning protection device to ensure the safe and stable operation of the electromechanical system.

Dynamic stability of the functioning of current earth fault directional protection in networks with isolated neutral

In distribution 6–10 kV networks with an insulated neutral for earth fault protection, zero sequence current directional protection devices are commonly used. According to the operation data, the main disadvantage of such kind of protection is the possibility of their functioning failures in transient conditions with the most dangerous for network intermittent arc earth faults. It is known that most earth faults in 6–10 kV networks, primarily in the initial stage of insulation damage, have an intermittent arc. Operation failures of zero sequence current directional protection in case of arc faults reduce the operational reliability of the protected network and, as a result, the reliability of power supply to consumers. Nowadays, new developments of electrical power systems relay protection devices, including earth fault protection of medium voltage distribution electrical networks, are implemented only on a microprocessor base. Therefore, the selection and justification of the implementation principles of zero sequence current directional protection which can provide high dynamic stability of functioning is a relevant objective. When analyzing the dynamic stability of the functioning of zero sequence directional current protection, regarding the complexity of transients during intermittent arc earth faults in medium voltage electrical networks with an isolated neutral, the simulation in Matlab using SimPowerSystem and Simulink was carried out. This study focuses on transient currents and voltages as the main factor influencing dynamic stability of the functioning of zero sequence current directional protection. The impact of other factors, for example, the inaccuracies of the primary zero sequence current and voltage transducers, the scheme of formation of compared quantities, etc. was not taken into account in simulation models. The study has allowed determining the causes of possible functioning failures of digital current earth fault directional protection in dynamic operation modes. It has been shown that the usage of orthogonal components of fundamental frequency of zero sequence voltage and current in current directional protection devices eliminates the failure of their operation with any kind of arc earth faults. To ensure high dynamic stability of operation under the influence of transients during arc intermittent earth faults, current directional protection for this type of damage should be performed on the basis of monitoring the phase relationships of the fundamental frequency components of 50 Hz of zero sequence voltage and current, but not their full values.

A study of the real-world noise attenuation of the current hearing protection devices in typical workplaces using Field Microphone in Real Ear method.

Actual noise reduction of the earmuffs is considered as one of the main challenges for the evaluation of the effectiveness of a hearing conservation program. The current study aimed to determine the real world noise attenuation of current hearing protection devices in typical workplaces using a field microphone in real ear (FMIRE) method. In this cross-sectional study, five common earmuffs were investigated among 50 workers in two industrial factories with different noise characteristics. Noise reduction data was measured with the use of earmuffs based on the ISO 11904 standard, field microphone in real ear method, using noise dosimeter (SVANTEK, model SV 102) equipped with a microphone SV 25 model. The actual insertion losses (IL) of the tested earmuffs in octave band were lower than the labeled insertion loss data (p < 0.05). The frequency nature of noise to which workers are exposed has noticeable effects on the actual noise reduction of earmuffs (p < 0.05). The results suggest that the proportion of time using earmuffs has a considerable impact on the effective noise reduction during the workday. Data about the ambient noise characteristics is a key criterion when evaluating the acoustic performance of hearing protectors in any workplaces. Comfort aspects should be considered as one of the most important criteria for long-term use and effective wearing of hearing protection devices. FMIRE could facilitate rapid and simple measurement of the actual performance of the current earmuffs employed by workers during different work activities.