Supply Frequency Research Articles

Fault Detection based on MCSA for a 400Hz Asynchronous Motor for Airborne Applications

Future health monitoring concepts in different fields of engineering require reliable fault detection to avoid unscheduled machine downtime. Diagnosis of electrical induction machines for industrial applications is widely discussed in literature. In aviation industry, this topic is still only rarely discussed. A common approach to health monitoring for electrical induction machines is to use Motor Current Signature Analysis (MCSA) based on a Fast Fourier Transform (FFT). Research results on this topic are available for comparatively large motors, where the power supply is typically based on 50Hz alternating current, which is the general power supply frequency for industrial applications.
 In this paper, transferability to airborne applications, where the power supply is 400Hz, is assessed. Three phase asynchronous motors are used to analyse detectability of different motor faults. The possibility to transfer fault detection results from 50Hz to 400Hz induction machines is the main question answered in this research work. 400Hz power supply frequency requires adjusted motor design, causing increased motor speed compared to 50Hz supply frequency. The motor used for experiments in this work is a 800W motor with 200V phase to phase power supply, powering an avionic fan. The fault cases to be examined are a bearing fault, a rotor unbalance, a stator winding fault, a broken rotor bar and a static air gap eccentricity. These are the most common faults in electrical induction machines which can cause machine downtime. The focus of the research work is the feasibility of the application of MCSA for small scale, high speed motor design, using the Fourier spectra of the current signal.
 Detectability is given for all but the bearing fault, although rotor unbalance can only be detected in case of severe damage level. Results obtained in the experiments are interpreted withrespect to the motor design. Physical interpretation are given in case the results differ from those found in literature for 50Hz electrical machines.

Fault Investigation of Circulation Pumps to Detect Impeller Clogging

Pumps have a wide range of applications. Methods for fault detection of motors are increasingly being used for pumps. In the context of this paper, a test bench is built to investigate circulation pumps for faults. As a use case, the fault of impeller clogging was first measured and then examined with the help of motor current signature analysis. It can be seen that there are four frequencies at which there is an increase in amplitude in case of a fault. The sidebands around the supply frequency are in particular focus. The clogging of three and four of a total of seven channels leads to the highest amplitudes at the fault frequencies. The efficiency is reduced by 9 to 15% in case of faulty operation. These results indicate that the implementation of fault detection algorithms on the pump electronics represents added value for the pump operator. Furthermore, the results can be transferred to other applications.

Composite synchronization of four exciters driven by induction motors in a vibration system

In this paper, a newly composite synchronization scheme is proposed to ensure the straight line vibration form of a linear vibration system driven by four exciters. Composite synchronization is a combination of self-synchronization and controlled synchronization. Firstly, controlled synchronization of two pairs of homodromous coupling exciters with zero phase differences is implemented by using the master–slave control structure and the adaptive sliding mode control algorithm. On basis of controlled synchronization, self-synchronization of two coupling exciters rotating in the opposite directions is studied. Based on the perturbation method, the synchronization and stability conditions of composite synchronization are obtained. The theoretical results indicate that composite synchronization of four exciters with zero phase differences can be implemented with different supply frequencies and the straight line vibration form of the linear vibration system also can be obtained. Some simulations are conducted to verify the feasibility of the proposed composite synchronization scheme. The effects of some structural parameters on composite synchronization of four exciters are discussed. Finally, some experiments are operated to validate the effectiveness of the proposed composite synchronization scheme.

Modal analysis of dielectric barrier discharge-based argon cold plasma jet

AbstractIn this study, an atmospheric pressure dielectric barrier discharge-based argon plasma jet has been modeled using COMSOL Multiphysics, which is based on the finite element method. The fluid dynamics and plasma modules of COMSOL Multiphysics code have been used for the modeling of the plasma jet. The plasma parameters, such as electron density, electron temperature, and electrical potential, have been examined by varying the electrical parameters, that is, supply voltage and supply frequency for both cases of static and with the flow of argon gas. The argon gas flow rate was fixed at 1 l/min. Ring electrode arrangement is subjected to a range of supply frequencies (10–25 kHz) and supply voltages (3.5–6 kV). The experimental results of the ring electrode configuration have been compared with the simulation analysis results. These results help in establishing an optimized operating range of the dielectric barrier discharge-based cold plasma jet in the glow discharge regime without arcing phenomenon. For the applied voltage and supply frequency parameters examined in this work, the discharge was found to be consistently homogeneous and displayed the characteristics of atmospheric pressure glow discharge.

Benchmarking-Based Investigation on Energy Efficiency of Low-Power Microcontrollers

As a real boost to competitiveness and productivity for sectors, such as health, agriculture, or industry 4.0, the Internet-of-Things (IoT) market is transforming business models and revolutionizing practices. A major challenge is to develop applications with high computing potential with limited resources. To satisfy both high-level performance and low-power requirements, a deep characterization method for microcontrollers is proposed since selecting the appropriate device is a central pillar of smart energy policy. The high-level analysis investigates the potential of various low-power microcontrollers with a benchmark utilizing a periodic duty cycle model of typical WSN applications. Afterward, deep characterization was carried out in two steps. The preselection phase is based on estimation whose results will serve as input for the second measurement phase. A highly accurate four-wire measurement involving guarding and shielding of all interfaces and the measurement cave is used for all measurements. To make the results comparable, a normalized power, defined as a measure of power per throughput, is introduced. The measurement characterizes the active power consumption depending on the supply voltage and frequency as well as sleep power, data logging power, and peripherals power.

Optical Fiber Sensor Encapsulated in Carbon Fiber Reinforced Polymer for Fault Detection in Rotating Electrical Machines

This paper introduces a novel fiber-based sensor for dynamic strain and temperature measurements in the stator of rotating electrical machines. Fiber Bragg grating sensors were integrated into carbon fiber reinforced polymer. The encapsulation has appropriate mechanical energy transfer to measure dynamic strain and temperature. The proposed sensor is installed in the stator of the induction motor allowing to analyze the dynamic strain generated by the machine. The main failure in induction motors is attributed to bearing failures. In this work, the tests were performed operating at full load with new and defective bearings. The results show the main peaks of frequency caused by strain observed coincide with the electrical supply frequency (60 Hz) and mechanical bearing forces (30 Hz), with harmonic components at 120, 180, and 240 Hz. However, for the damaged bearings frequencies of 89.8, 116.5, 146.4, and 149.7 Hz were identified. These frequency components were generated by defects in the outer race, rolling element and inner race. The fundamental components of 30 and 60 Hz between the new and damaged bearings presents an increase of more than 75 %. Results show the potential of the proposed sensor in the monitoring of temperature and dynamic strain in electrical machines.

Fault Diagnosis of Planetary Gearbox Based on Motor Current Signal Analysis

Planetary gearbox is one of the most widely used core parts in heavy machinery. Once it breaks down, it can lead to serious accidents and economic loss. Induction motor current signal analysis (MCSA) is a noninvasive method that uses current to detect faults. Currently, most MCSA-based fault diagnosis studies focus on the parallel shaft gearbox. However, there is a paucity of studies on the planetary gearbox. The effect of various signal processing methods on motor current and the performance of different machine learning models are rarely compared. Therefore, fault diagnosis of planetary gearbox based MCSA is conducted in this study. First, the effects of various faults on motor currents are studied. Specifically, the characteristic frequencies of a fault in sun/planet/ring gears and supporting bearings of the planetary gearbox are derived. Then, a signal preprocessing method, namely, singular spectrum analysis (SSA), is proposed to remove the supply frequency component in the current signal. Subsequently, four classical machine learning models, including the support vector machine (SVM), decision tree (DT), random forest (RF), and AdaBoost, are used for fault classifications based on the features extracted via principal component analysis (PCA). The convolutional neural network (CNN), which can automatically extract features, is also adopted. The dynamic experiment of the planetary gearbox with seven types of faults, including tooth chipping in sun/planet/ring gears, inner race spall in planet bearing, inner/outer races, and ball spalls in input support bearing, is conducted. Raw current signal in the time domain, reconstructed signal by SSA, and the current spectra in the frequency domain are used as the inputs of various models. The classification results show that the PCA-SVM is the best model for learned data while CNN is the best model for unlearned data on average. Furthermore, SSA mainly increases the accuracy of CNN in the time domain and exhibits a positive effect on unlearned data in the time domain. The classification accuracy increases significantly after transforming the time domain current data to the frequency domain.

A 5 GHz 0.5 V Hybrid Class-B/F−1 CMOS Oscillator With −147 dBc/Hz Phase Noise at 10 MHz Offset Using Body-Biased 22 nm FDSOI

This work presents a self-biased 5 GHz hybrid class-B/F−1 oscillator for low phase noise and robust startup. The design exploits the concurrent conduction of nMOS and pMOS, when placed on differential sides, to form a differential-mode (DM) high-quality-factor second-harmonic resonator for low phase noise. The same resonator is shared between the main core (class-F−1) and the startup core (class-B), to allow phase noise reduction. The hybrid CMOS oscillator is fabricated in 22 nm fully depleted silicon-on-insulator (FDSOI) using thin-oxide-only devices, operated from 0.5 V supply, and achieves a phase noise <−147 dBc/Hz at 10 MHz offset across 11% tuning range. The peak figure of merit (FoM) is 190 dBc/Hz, and the supply frequency pushing ranges from 20–44 MHz/V, whereas the power consumption is from 15 to 18 mW. To the authors’ knowledge, the hybrid class-B/F−1 oscillator delivers the lowest phase noise using a 0.5 V supply at 5 GHz.

Generation Characteristics of Long-Lived Active Species in a Water Falling Film DBD Reactor

Water falling film dielectric barrier discharge (WFFDBD) has been widely studied for water treatment, due to its good performance on production of active species, mass transfer of active species from gas phase into liquid phase, and therefore the degradation of pollutants. However, few studies have focused on the production characteristics of active species of WFFDBD. In this paper, the formation characteristics of hydrogen peroxide, ozone and nitrate ions in a WFFDBD reactor powered by bipolar pulsed generator were studied under different electric discharge time, peak pulse voltage, power–frequency, air flow rate, water circulation flow rate, pH value and conductivity. The results show that the concentrations of hydrogen peroxide, ozone and nitrate ions increased with the peak pulse voltage, power supply frequency and water circulation flow rate, but the inputted air flow rate presented different effect on the production of active species. Moreover, the increase in pH value and conductivity led to a decrease in the concentration of hydrogen peroxide, while nitrate ion increased with the water pH value and conductivity. The p-nitrophenol degradation result indicates that both ozone and hydrogen peroxide contribute to its degradation possibly via their reaction into hydroxyl radical.

Seismic noise in an urban environment

The results of an experiment aimed at identifying the nature of major noise sources within an urban area are described. We found the strongest noise source to be an irrigation pump located adjacent to the geophones. The noise from the pump had a narrow bandwidth centered at 75 Hz with a duration of 5 minutes every 17 and 34 minutes during the day and night, respectively. Traffic noise was mainly restricted to between 10 and 25 Hz, with its strength decreasing between 9 p.m. and 6 a.m. Passing aircraft resulted in noise between 30 and 200 Hz lasting about 1 minute. Electrical noise was observed at the supply frequency of 50 Hz, although additional noise at 45 Hz also was observed. Given these results we recommended that acquisition within the area should be restricted to late evening or early morning, receiver locations should be selected to avoid strong localized sources of electrical and/or mechanical noise, and any cables associated with the recording system should be as short as possible (although nodal systems are preferable). If nodal systems are deployed for logistical reasons, real-time noise monitoring should be deployed to identify and avoid bursts of high-amplitude, short-duration noise.

An Adaptive Feed-Forward Phase Locked Loop for Grid Synchronization of Renewable Energy Systems under Wide Frequency Deviations

Synchronization is a crucial problem in the grid-connected inverter’s control and operation. A phase-locked loop (PLL) is a typical grid synchronization strategy, which ought to have a high resistance to power system uncertainties since its sensitivity influences the generated reference signal. The traditional PLL catches the phase and frequency of the input signal via the feedback loop filter (LF). In general, to enhance the steady-state capability during distorted grid conditions generally, a filter tuned for nominal frequency is used. This PLL corrects large frequency deviations around the nominal frequency, which increases the PLL’s locking time. Therefore, this paper presents an adaptive feed-forward PLL, where the input signal frequency and phase under large frequency deviations are tracked precisely, which overcomes the above-mentioned limitations. The proposed adaptive PLL consists of a feedback loop that reduces the phase error. The feed-forward loop predicts the frequency and phase error, and the frequency adaptive FIR filter reduces the ripples in output, which is due to input distortions. The adaptive mechanism adjusts the gain of the filter in accordance with the supply frequency. This reduces the phase and frequency error and also decreases the locking time under wide frequency deviations. To verify the effectiveness of the proposed adaptive feed-forward PLL, the system was tested under different grid abnormal conditions. Further, the stability analysis has been carried out via a developed prototype test platform in the laboratory. To bring the proposed simulations into real-time implementations and for control strategies, an Altera Cyclone II field-programmable gate array (FPGA) board has been used. The obtained results of the proposed PLL via simulations and hardware are compared with conventional techniques, and it indicates the superiority of the proposed method. The proposed PLL effectively able to tackle the different grid uncertainties, which can be observed from the results presented in the result section.

Research on Deep-Sea Pipeline Tube Bundle Heating System

In order to ensure the safety of deep-sea submarine pipelines, this paper focuses on the analysis of the axial temperature distribution model of the submarine pipeline and the distribution parameter circuit model of the tube bundle heating system. Combined with these two models, theoretical analysis shows that the heating effect of the tube bundle heating system depends on the distributed circuit parameters and power frequency of the system. In order to improve the heat tracing efficiency, the power frequency needs to be adjusted according to the change of the load temperature, so the power supply frequency of the tube bundle heating system based on the Hammerstein model is optimized. Using a neuro-fuzzy algorithm, not only the theoretical values of heating power and power frequency are obtained, but also the drawbacks of determining the above parameters based on engineering experiments are avoided. Moreover, the pipeline heating is efficient and stable, the dynamic response is fast, and the working condition is also well adapted.

Modifications and Improvements to the Collector Metal Method Using an mhd Pump for Recovering Platinum from Used Car Catalysts

Today recovery of platinum from used auto catalysts has become a necessity due to great demand for this catalytic metal. There are many methods of recovering platinum from used catalysts on the market, one of them is the original collector metal method using the magneto-hydrodynamic (mhd) pump. This method is based on the continuous flow of the collector metal (lead) in the channel of the device, which can be obtained by using the mhd pump at the device operating temperature of 673 K. Proper selection of process parameters such as power frequency (25–100 Hz), inductor current density (20 A, 40 A, 60 A), gaps between the inductor and the liquid metal channel (2,4,8), flow velocity, secondary voltage (19 V, 40 V, 60 V) ensures proper efficiency of the device. Some parameters were selected on the basis of numerical simulations, others were experimentally verified—the tests were carried out for different washing out times (600 s to 3600 s), and different secondary voltage and inductor supply frequency (25 Hz to 45 Hz). Platinum washing out efficiency of up to 98% was obtained with a relatively short washing out time and low values of secondary voltage and inductor frequency. To improve the efficiency of the process, the thermal efficiency of the device was increased by 8% by insulating the cover of the device. Further modifications to the process include changing the collector metal—preliminary studies show that the addition of lithium increases the extraction of platinum from thin catalytic layers as a result of reduced surface tension of the extraction liquid. The preliminary results of the PbLi alloy spread on platinum coated surface seem to be very promising.

Rotor fault diagnosis of frequency inverter fed or line-connected induction motors using mutual information

Characteristics like robustness, adaptability to several load conditions, and low costs of operation and maintenance are some of the reasons three-phase induction motors are ubiquitous in industrial applications. Even so, these machines are subjected to electrical and mechanical faults which can result in malfunction. The detection of incipient faults is the focus of several recent studies because they provide information for timely decisions to avoid unplanned stops of industrial processes. A common problem of induction motors is the presence of broken rotor bars. Most of the methods of condition monitoring and fault diagnosis focus on the usage of only one type of power supply: line-connected or fed by frequency inverters. Given this situation, we present an alternative technique for the detection of broken rotor bars of three-phase induction motors regardless of the type of power supply. Our approach is based on similarity measures of the stator current signals of two motor phases in order to extract the relevant features of such signals, which are then classified using three intelligent systems: artificial neural network, support vector machines, and k-nearest neighbors. We performed 3310 experimental tests with motors operating in steady state, with sinusoidal and non-sinusoidal power supply, and variations of voltage unbalance levels, supply frequency, and load torque. Classification accuracy rates over 92% of success were obtained in these tests, which validate the proposed approach.

Power supply efficiency in dual magnetron large area sputter coatings

In large area sputter coating of glass, the consumption of electric power is one of the major cost drivers. This applies especially to dielectric transparent coatings which are relatively thick and for which sputter yields and rates can be rather low. These materials are usually sputtered from dual magnetrons using medium frequency (sine wave) or bipolar (square wave) power supplies at frequencies up to 100 kHz. Frequencies at 50 kHz or higher are beneficial for suppressing arcing on the target surface, and the power required to achieve viable sputter rates is often high, making the power consumption a significant cost contribution. In this study we look at the effect of the power supply technology and frequency on the sputter rate and the sputtered layer thickness per electrical energy input. The tests were carried out with aluminum dual planar targets and with TiOx dual rotary targets. At low frequencies around 20 kHz, the bipolar generator can yield about 10% higher sputtering rates at the same input power. At about 40 kHz, which is often chosen to minimize arcing, the rates from the two power supplies are about equal.

Fuzzy inference based irrigation controller for agricultural demand side management

The efficient and sustainable irrigation mechanism results in reduced water loss and improved crop productivity. This paper presents a real-time fuzzy inference based automated irrigation controller implemented in LabVIEW, that utilizes the data logged from the sensor network and communicated using GSM/GPRS module. The proposed drip irrigation scheduler receives the data from soil moisture, humidity, air temperature and water level sensor, in order to decide the percentage valve opening. Recently the open channel system have transformed into pressurized pipe systems which utilizes large amount of energy for uniform distribution of water. In order to optimize the energy consumption utilized in irrigation, availability based tariff (ABT) is implemented. The time interval for which drip irrigation is regulated, is controlled by supply frequency to operate pumps in low tariff period. This technique is applicable for wide range of crops which are grown in Kharif and Rabi season. The field experimentation results shows that the cost of irrigation is reduced by 30% as the water and electricity is efficiently utilized. Water saving is 45% more as compared to flood irrigation mechanism. Cost benefit achieved for Sorghum crop cultivation by proposed fuzzy based irrigation technique is higher by Rs.598/acre than the profit realized by manual flood irrigation.

Altering Supply Frequency to Prevent the Theft of Electric Power at Distribution End

Altering Supply Frequency to Prevent the Theft of Electric Power at Distribution End - written by Vrushabh Patil , Jay Tijare , Pratik Damedhar published on 2020/06/08 download full article with reference data and citations

Influence of supply voltage and frequency variations on the electrical equipment and power consumption in LV and MV distribution networks

This paper is focused on the analysis of supply voltage and frequency quality in low voltage and medium voltage distribution power systems. The influence of supply voltage and frequency variations, within the limits defined in the valid standards, on the power network’s parameters has been evaluated using the stochastic theory and the statistical analysis methods. The circuit of RLC-load was considered for numerical evaluation. The probability distribution of supply voltage and frequency was defined and the suggestions on optimum voltage and frequency quality parameters regarding electric energy consumption, power losses and electrical equipment lifespan were given.

Effects of Resonance Phenomenon Caused by Power Supply on JT-60SA CS

The maximum voltage between the CS module terminals is designed to be 10 kV, the voltage between the layers under ideal conditions is then about 0.38 kV because the CS module has 52 layers. But, in operating condition, there is a possibility that the voltage between the layers is higher than 0.38 kV due to the voltage fluctuations of the power supply and the inhomogeneous voltage distribution in the CS module induced by the resonance phenomenon. The JT-60SA CS consists of four electrically independent stacked CS modules. It might even produce voltages high enough to damage the insulation between the CS conductors. In the present study, which is based on the results of previous studies, we created a circuit simulation model for the JT-60SA CS (four CS modules), including the structures (ground resistances, CS structure, TFC cases, and EFC covers), and used it to estimate the voltage distribution produced by the resonance phenomenon. From these results, we conclude that the resonance phenomenon caused by power supply frequency components does not impact the insulation between the CS conductors, and hence the JT-60SA CS is electrically stable under normal operating conditions.

ACOUSTIC EMISSION TESTING OF POWER TRANSFORMERS INSULATION

Testing results of power transformers insulation for the presence of insulation defects, accompanied by the partial discharges occurrence, by means of the acoustic emission method are presented in this article. In particular, the testing of two power transformers with different lifetime was carried out. One transformer was defect-free and one with a willing insulation defect. Based on the testing results, the features of acoustic emission data for power transformers in the presence of partial discharges are found. High sensitivity of acoustic emission method for acoustic wave registration from partial discharges is shown in the article. A method for filtering of noise hits and extraction of hits from partial discharges is proposed. This method is based on excretion of acoustic emission hits from partial discharges out of total number of hits by means of periodicity of their registration, which is synchronized with power supply frequency on the first step. On the next step based on acoustic emission parameters of hits excretion on the previous step, filtration was carried out. The location of the insulation defect which led to the appearance of partial discharges was determined based on the volume location algorithm, by means of acoustic emission method. The insulation defect was confirmed by verification.