Showing papers on "Impulse generator published in 2014"

Portable Grounding Impedance Meter Based on DSP

Abstract: A new grounding impedance measuring system based on digital signal processor (DSP) platform was developed. The low-cost portable device includes a built-in voltage impulse generator, nonvolatile memory for storage of measured current and voltage waves and a graphical display for fast data visualization. General hardware structure overview and software implementation are discussed. Consistent preliminary field-test results were provided by the measuring system, consisting of records of grounding potential rise and impressed current, impulse impedance, and estimated low-frequency grounding resistance obtained for different electrode arrangements buried in low- and high-resistivity soils.

Miniaturized direct digital-to-impulse radar sensors in silicon

Abstract: A radar system may comprise a trigger, driver, switching circuit, and antenna for generating an ultra-short impulse without utilizing an oscillator. A radar imaging system for imaging a formation or a cross section of a pipeline may include at least one radar sensor. The system may transmit a high-frequency, short impulse signal to a formation or pipeline and measure a reflected signal. A high speed impulse generator may allow the short impulse signals to be generated. This impulse generator may utilize a switching circuit and digital driver to provide the short impulse signals. The images provide useful information about complex permittivity of the formation, the geometry of the pipeline, deposition thickness of asphaltenes and wax, velocity of the fluid, as well as size, type, concentration of gas bubbles, water, or solid particles in the flow, or combinations thereof.

Converter With Four Quadrant Switches for EDM Applications

Abstract: This paper presents a high-frequency rectifier stage using four quadrant switches as synchronous rectifiers for an electrical discharge machining (EDM) power supply. The EDM impulse generator is a series-parallel resonant inverter operating in current-mode. The device specifications and drive requirements of the converter are studied with the objective of generating unipolar and bipolar current waveforms suitable for different types of EDM operations.

Measurement and analysis of transient overvoltage distribution in the low-voltage winding of 1000 kK power transformer without oil immersion

Abstract: High frequency voltage oscillations will be generated when transient overvoltages intrude into power transformers. These oscillations may cause damage to the insulation of transformers. In this paper, a capacitive coupling sensor array was presented for measuring voltage distributions and voltage gradient distributions in low-voltage winding of a 1000 kV power transformer. A variable impedance transmission line between impulse generator and winding was also designed to avoid distortion of the applied impulses. The results indicate that under the lightning impulse voltages, voltage distributions have been restrained below applied voltage at sandwich-interleaved section but exceed the applied voltage in continuous coils in the first half of the winding and lead to a very nonuniform voltage distribution. Longer duration time will result in a more nonuniform distribution. The amplitude of the transient voltage under steep front square wave reduces faster downward the winding than that under lightning impulse voltages. A shorter rise time will lead to a much worse distribution. In addition, a dominated oscillation of 63 kHz is found under both impulse voltages and steep front square waves.

Practical simulation and modelling of lightning impulse voltage generator using marx circuit

Abstract: Standard impulse waveform have similar characteristics as that of lightning strike and can be used for testing the strength of electrical equipment. For producing high voltage pulses Marx generator is the most popular and is most widely used method. This thesis describes the creation of a simulation circuit to match the output of a Marx Impulse Generator. In this project eight stages of standard Marx Impulse Voltage Generator were simulated and resulted impulse waves were recorded. The objective was to calculate the stray capacitance using standard formulas and embed that capacitance into the simulation circuit to adequately deliver a yield like that of the impulse generator. A genuine multi-staged impulse generator was utilized as the base. Eight distinctive levels of impulse voltage were tried, and the output waveforms were recorded. The simulation circuit was then subjected to a few cycles, conforming the capacitance qualities to achieve a yield as close as could be expected under the circumstances to that of the real generator. Finishes of the examination demonstrate that a successful simulation circuit could be made to give a yield that is near, yet not precisely that of, the genuine generator. In the exploration, a few zones of error were distinguished in the simulation that were not introduce in the simulation circuit. The entire simulations have been examined in the NI Multisim software. The simulation circuit could be utilized to figure out the front time, tail time, and peak voltage.

저압용차단기 전원 개폐시 개인용 pc에 미치는 영향 분석

Abstract: This paper describes the analysis of the effect on personnel computer in case of turning off power supply of main breaker in general electrical installation. In order to analyze the effect on personnel computer in case of turning off the power supply of main breaker, the switching impulse generator has been designed and fabricated which makes it possible to evaluate the effect on electrical product by switching impulse. The switching impulse tests were carried out for personnel computer according to applied voltage and number of switching impulse. As a consequence, switching impulse had not a significant influence on personnel computer in this study. The varistor of power input section functions as a protection of switching impulse as well as lightning impulse. The results will be used to related organization, and electrical product manufacturer, and residents.

Impulse circulatory cleaning device for heat exchangers

Abstract: The utility model provides an impulse circulatory cleaning device for heat exchangers. The impulse circulatory cleaning device for the heat exchangers is mainly characterized by comprising a gas buffering tank, an impulse generator, a gas-liquid mixer and a switching valve, wherein the gas buffering tank is used for providing compressed air; a gas inlet of the impulse generator is connected with a gas outlet of the gas buffering tank; the gas-liquid mixer is provided with a gas-phase inlet, a liquid-phase inlet and a gas-liquid outlet; the liquid-phase inlet is connected with an outlet of a cleaning pump; the switching valve is provided with a water inlet, a discharging opening, a circulatory water supplying opening and a circulatory water returning opening; and the water inlet is connected with the gas-liquid outlet. A gas-liquid impulse cleaning technology, a chemical circulatory cleaning technology and a circulatory cleaning technology are combined; and the impulse circulatory cleaning device has the advantages of high cleaning efficiency, high adaptability, low cleaning cost, easiness and convenience in use and operation and the like. Moreover, the impulse circulatory cleaning device can be used for cleaning various heat exchangers under the condition that a machine set works continuously.

Extremely high lightning currents a newly designed surge generator and some practical applications

Abstract: The paper describes the simulation of extremely high lightning currents by means of a newly designed twin crowbar spark gap lightning current generator. Extremely high lightning currents up to 400 kA 10/350 μs can be generated. For the simulation of these high lightning currents, a parallel connection of two capacitive surge current generators with crowbar spark gap has been realized. This test generator can also produce multiple impulse currents with high peak currents and corresponding high charge transfer. It is also shown how to simulate in the laboratory high peak currents and long continuous currents in one combined test current. Direct effect lightning current testing to simulate the effects of cloud-to-ground lightning flashes is demonstrated on various practical applications such as air-termination systems, down conductors and connection components for LPL I and above. Furthermore, a high current test on surge protective devices (SPDs) for extreme installation conditions is shown. Finally, the test generator also enables high-current impulse testing of test objects with relatively high impedances such as wind turbine rotor blade samples.

Method of Controlling Corona Effects and Breakdown Voltage of Small Air Gaps Stressed by Impulse Voltages

Abstract: This paper investigates the influence of a resistor on the dielectric behavior of an air gap. The resistor is connected in series with the air gap and the latter is stressed by impulse voltage. Air gap arrangements of different geometry with either the rod or the plate grounded are stressed with impulse voltages of both positive and negative polarity. The resistor is connected in series with the air gap in the return circuit connecting the gap with the impulse generator. The method followed involves the investigation of the graphs of the charging time concerning the air gaps capacitances, in connection to the value of the resistor, the geometry of the gap, the effect of grounding and the polarity effect. It is determined that the charging time of the air gap increases, as the value of the resistor increases. It is also determined that the peak voltage value of the fully charged air gap decreases as the value of the resistor increases. The results of the mathematical and simulation analysis are compared with the results of the oscillograms taken from experimental work. In addition and consequently to the above results it is concluded from the experimental work that the in series connection of the resistor in the circuit has significant influence on corona pulses (partial discharges) occurring in the gap and on the breakdown voltage of the gap. A new method of controlling the corona effects and consequently the breakdown voltage of small air gaps stressed by impulse voltage of short duration in connection to the ground effect and the polarity effect has arisen. Furthermore through mathematical analysis of the charging graphs obtained from simulation and experimental oscillograms there was a calculation of the values of the capacitance of the air gaps in relation to their geometry and the results were compared to the values calculated with mathematical analysis.

Sliding friction based impulse generator and power generation method

Abstract: The invention provides a sliding friction based impulse generator and a power generation method. The generator comprises a first friction layer, a second friction layer and a touch switch, wherein the upper surface of the first friction layer is provided with a first electrode layer in a contact mode, the lower surface of the second friction layer is provided with a second electrode layer in a contact mode, the first electrode layer and the second electrode layer are conducted through turning on the touch switch after sliding friction is generated between the lower surface of the first friction layer and the upper surface of the second friction layer and the contact area is changed, the touch switch is turned off after the impulse generator outputs impulse electric signals, and so on. Mechanical energies such as rotations, vibrations and the like applied to the generator are converted into the impulse electric signals to output.

Test Research on Phase-to-Ground Air-Gap Discharge Characteristics of UHV Substation

Abstract: In order to optimize the design of UHV substation and reduce its construction investment, it is necessary to take further research of UHV substation air-gap discharge characteristics. In this paper, by using sub-conductor and tower to simulate UHV substation air-gap, lightning and switching impulse discharge characteristics tests of UHV substation are taken in the UHV AC test base of SGCC. The results show that, when the distance of conductor between tower is in range of 4m to 7m, the 50% lightning impulse and switching impulse discharge voltage rise along with the rise of air gap distance. As the air-gap increases, the switching impulse discharge voltage presents the trend of saturation. According to the analysis of test results, we can draw a conclusion that the gap factor of switching impulse discharge can be 1.22 when the minimum distance between conductors and tower is 5~8m.

High-frequency impulse generator and loading system thereof

Abstract: The invention discloses a high-frequency impulse generator and a loading system of the high-frequency impulse generator. The high-frequency impulse generator comprises a static plate, a movable plate, a main transmission shaft, a shell, a tapered roller bearing set, a rotation sealing ring, a framework oil seal, a bearing cover, a front end cover, a rear end cover and an O-shaped sealing ring. The loading system of the high-frequency impulse generator comprises a pressure gauge, an accumulator, a pressure oil filter, an alternative-current servo motor, the impulse generator, a loading actuator a one-way valve, a quantification oil pump, a screen filter, an oil tank, a variable-frequency and variable-speed motor and an overflow valve. The high-frequency impulse generator and the loading system of the high-frequency impulse generator thoroughly change a current fatigue test loading technology and make a significant breakthrough in the current fatigue test loading technology. According to the high-frequency impulse generator and the loading system of the high-frequency impulse generator, all the possibilities of static, low-frequency and high-frequency test loading are included and organically integrated, the design of a fatigue test machine is simplified, the measuring and controlling difficulty is reduced, the performances of the fatigue test machine are promoted, and the wide market prospect and the good social benefits are achieved.

Experimental and analytical studies of the effects of multiple lightning impulse currents on metal-oxide arrester blocks

Abstract: The multiple lightning strokes are the main cause of distribution arresters failures. In order to evaluate performance of distribution lines arresters more realistically, the experimental and analytical studies of the effects of multiple lightning impulse currents on metal-oxide arrester blocks are carried out. The multiple impulse current generator developed by Shanghai Jiao Tong University is adopted, the generator could output four impulse current representing one first stroke current, two subsequent stroke current and one continuing current of interval stroke, respectively. The variable interval time between the two impulses could achieve as low as 1 ms. The effects of block dimension, interval time between impulse currents, the sequences of impulse currents and the amplitude of impulse currents are studied. The results show larger amplitude of multiple impulse current, less interval time between impulse currents and smaller geometric parameter of arrester block are the causes of blocks failure. Surface flashover and energy absorption are two failure characteristics under multiple impulse current. The DC 1mA reference voltage is more sensitive than the residual voltage of blocks under multiple impulse current. The multiple impulse currents tests are suitable for performance evaluation of distribution lines arresters under natural lightning stroke.

Parameters Optimization of Impulse Generator Circuit for Generating First Short Stroke Lightning Current Waveform

Abstract: This paper presents the parameters optimization technology for generating the first short stroke lightning current waveform(10/350 μs) which is necessary for the performance tests of components of lightning protection systems, as required under IEC 62305 and the newly amended IEC 62561. The circuit using the crowbar device specified in IEC 62305 was applied to generate the lightning current waveform. To find the proper parameters of the circuit is not easy because the circuit consists of two parts; circuit I, which relates to the front of current waveform, and circuit II, which relates to the tail. A simulation in PSpise was carried out to find main factors related to the front and tail of 10/350 μs. The lightning current generator was developed by utilizing the circuit parameters found in the simulation. In the result of experiments, new parameters of the circuits need to be changed because of the difference between the simulation and the experiment results. Using the iterative method, the optimized parameters of the circuits was determined. Also a multistage-type external coil and a damping resistor were proposed to make the efficiency of generation to enhance. According to the result in this paper, an optimized first short stroke lightning current waveform was obtained.

Influence of different impulse waveforms on coordination of two cascaded SPDs

Abstract: 2014 International Conference on Lightning Protection, ICLP 2014, Shanghai, 11-18 October 2014

Advanced requirements on SPDs protecting sensitive equipment

Abstract: Nowadays SPDs are of essential importance to protect highly sensitive, electronic devices installed closely to electric distribution systems and switchgear installations. The increasing numbers of applications require that not only the different stages of SPDs, installed e.g. at the building entrance and in electric distribution systems, are well coordinated, but that they are also coordinated with the equipment to be protected. In these cases, the protective function of the SPDs has to be coordinated with the individual immunity of the equipment against energetic, conductive impulse voltages and impulse currents. It can be shown that the coordination behavior depends on the technology used as a protective component in the SPD. Current SPD standards [I], [2], electric installation standards [3] [4] and equipment EMC-standards [5] give requirements and test procedures that have to be fulfilled by the SPDs and have to be withstood by the equipment. In order to verify the immunity against partial lightning currents of the complete system laboratory tests on a system level are a suitable approach. The proposed test schemes for complete systems have been successfully performed on various applications. Examples will be presented.

Effects of motorette structure and vanish treatment on repetitive partial discharge inception voltage measurement test in inverter surge insulation

Abstract: The Inverter surge is a high-voltage phenomenon that is generated by the overlap returning waves by impedance mismatching among an inverter, cable and motor. The inverter has been available by advancement of control system of electrical instrument, such as the industrial motor. Insulation performance evaluation technology by partial discharge (PD) measurement is important because the mechanism leading to breakdown by the inverter surge is a cause of PD. In this study, a design methodology for the impulse generator for partial discharge test is developed. In addition, we measure repetitive PD inception voltage (RPDIV) at phase to phase, phase to ground and turn to turn in a motorette sample using automatic RPDIV measuring system and developed repetitive impulse voltage generator. As a result, it is found that generated voltage and current waveform varies depending on the motorette structure. It is also found that RPDIV of the motorette differs with and a without a varnish treatment. The repetitive impulse voltage is applied to confirm the insulation dignity of inverter-fed motor insulation.

A method for diagnosing a torque impulse generator

Abstract: A method for diagnosing a torque impulse generator which includes a rotational input portion, a torque output portion, an oil reservoir and a torque generating arrangement converting rotation of the input portion to torque impulses at the torque output portion, the method includes: detecting an acoustic signal from the torque impulse generator while generating torque impulses, extracting the frequency of torque impulses from the acoustic signal, and diagnosing the torque impulse generator based on the frequency of torque impulses, to indicate the level of oil in the oil reservoir.

Investigation of Wave Propagation to PV-Solar Panel Due to Lightning Induced Overvoltage

Abstract: Lightning produces extremely high voltages that generated induce overvoltage which have a high tendency to effect the electrical apparatus especially renewable energy plant that directly expose to this source. This study was performed through experimental work by investigating the effect of induce overvoltage upon the photovoltaic system. The induce voltage was performed by using lightning impulse generator. It is found that the maximum voltage of the unwanted signal is proportional with the distant of the specimen. The closer distant between solar panel material and spark discharge, the more serious effect would occur due to the induced overvoltage.

Design and implementation of a programmable high-voltage impulse measurement system

Abstract: High-voltage impulses (HVIs) are produced under laboratory conditions in order to emulate actual internal (switching) and external (lightning, thunderbolt) voltages. HVI resistance tests are essential to meet national and international standards on the production of electromechanical devices and materials, such as switchgears, and transformers that operate under these actual conditions. Accurate measurement of HVI is excessively difficult since the voltage level is so high, while the time parameters are relatively constricted. In this study, a reliable automatic HVI measuring and recording system, which accommodates a series of hardware and software designs in order to satisfy the constraints of the standards, is devised. The system provides high performance for measurement speed, resolution, and accuracy. Its lightweight, portable, and economical design brings about a prevalence of availability for medium- and small-scale electromechanical manufacturers.

Electrode device for transcranial electrostimulation

Abstract: FIELD: medicine.SUBSTANCE: invention relates to therapeutic devices for application in transcranial electrostimulation by the application of a respective electric impulse to ears simultaneously with playing music, which the patient hears. The device contains a generator of transcranial electrostimulation impulses, a generator of the sound signal, a control unit, a pair of audioearphones. The generator of transcranial electrostimulation impulses is made with a possibility of creating an electric impulse, which has such a frequency and duration as to provide the required microcurrent through the head. The control unit is made in the form of a microprocessor, controlling data of the electrostimulation impulse generator and the generator of the sound signal. Each audioearphone contains an electrode, transmitting electric current, for the application of the said impulses, produced by the impulse generator, into the area of the patient's ear. Each of the audioearphones and the respective electrode are combined into an electrode device, with the electrode of each electrode device being located on an external surface of the respective audioearphone, suitable for installation in an orifice of the auditory canal of the ear or inside it. The electrode of each electrode device has an area of electric contact for functional transmission of electric energy between the electrode and the patient's skin with the installed electrode device. The electrode devices are made with a possibility of installation in the orifice of the auditory canal of the respective ear of the said patient.EFFECT: application of the invention increases convenience of carrying out electrostimulation and simplifies installation of the equipment on a patient.6 cl, 6 dwg

Generation of ultrawideband picosecond impulses with fast fall‐time

Abstract: A method to generate ultrawideband picosecond impulses with fast fall-time is presented. This impulse generator is based on a broadband bipolar transistor and a nonlinear transmission line comb generator. The transistor works in fast switch-on mode and emits impulses with steep leading edges, which are further compressed by the comb generator. The experimental short impulses of 725 ps duration and 180 ps fall-time were generated with output harmonic up to 10 GHz. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2165–2167, 2014

Synthesis loop-based testing apparatus for forward recovery characteristic of thyristor

Abstract: The utility model relates to a testing apparatus of a direct-current power transmission converter valve, particularly to a synthesis loop-based testing apparatus for a forward recovery characteristic of a thyristor. The testing apparatus comprises a constant-current voltage source, a sample thyristor T, a diode D, an adjustable capacitor C, an adjustable saturable reactor L, a heating circuit, an impulse generator and a damping loop. According to the technical scheme, two sets of power supply systems are used for providing a charging voltage and a forward voltage for the sample thyristor. During testing, the current outputted by the constant-current voltage source and the voltage outputted by the impulse generator are exerted on a tested thyristor alternately. Therefore, the requirement of the forward recovery characteristic testing of the high-power semiconductor device on the conditions of different voltages, different frequencies, different trigger signals, different junction temperatures, different current peak values, and different di/dt conditions can be met. The testing method is simple and can be implemented easily; the needed equipment capacity is low; and the apparatus cost is low.

Hydraulic torque impulse generator

Abstract: A hydraulic torque impulse generator comprising a motor driven drive cylinder (12) with a chamber (15), an output shaft (20) coaxial with the drive cylinder (12) and connected to a radially movable seal element (24,25) supported on the impulse receiving portion (19) and dividing intermittently the chamber (15) into a high pressure compartment (32) and low pressure compartment (33), and cam profiles (27, 28) arranged to displace the seal element (24,25) from an idling position to a high pressure pulse generating position. A valve element (47) is movable between a closed position and an open position to control fluid flow through a by-pass passage (46) between the high pressure compartment (32) and the low pressure compartment (33). The valve element (47) is coupled to the drive cylinder (12) via a coupling (40) shifting the valve element (47) to its open position as the drive cylinder (12) is brought to an abrupt stop at impulse generation.

Impulse current testing system for simulating lightning effect

Abstract: This paper introduced the impulse current testing system for simulating lightning effects. The shield method to suppress the interference was addressed in this paper. After compared with three filter methods, it was verified that the wavelet transform is most suitable for measuring the impulse by using the digital filter technology to get the actual signal.

Modelling and simulation of impulse voltage generator using marx circuit

Abstract: Protection of power system is an important aspect for the continued service of the electrical power system. Mostly the protection of electrical power depends on the performance of insulation systems under transient over voltage conditions arises due to lightening and switching applications. Transient over voltages in addition to the abrupt changes in the state of power systems, e.g. switching operations or faults are known as switching impulse voltages and that due to lightening are known as lightening impulse voltages. Very short pulse high-voltage or high-current surges can be produced by an electrical apparatus known as impulse generator. High impulse voltages are used to test the durability of electric power equipment against lightning and switching surges. The Marx Impulse generator is used to generate such high impulse voltages. A total of eight stages of both Standard as well as Improved Marx Impulse generator were designed and the impulse waves were recorded. These recorded impulse waves were compared with the standard impulse wave with front time of 1.2µ seconds and fall time of 50µ seconds. The energy and efficiency of all the stages were calculated and the percentage of error in the rise time and fall time was also found out. The simulation was done with the help of NI Multisim Software Package. A small practical prototype of second stage of Standard Marx Impulse Generator circuit was also designed for a voltage source of 12 V and its output impulse wave was compared with that of the standard impulse wave.

Adjustable high-frequency impulse light source based on silicon-based micro-ring resonant cavity carrier chromatic dispersion effect

Abstract: The invention discloses an adjustable high-frequency impulse light source based on a silicon-based a micro-ring resonant cavity carrier chromatic dispersion effect. The adjustable high-frequency impulse light source comprises an incidence light source, a low-frequency electro-optical modulation system, a light amplifier, a high-frequency impulse generator, a light signal test system and a feedback control system. The low-frequency electro-optical modulation system is located on an optical path of the incidence light source. The input end of the light amplifier is connected with the output end of the low-frequency electro-optical modulation system. The input end of the high-frequency impulse generator is connected with the output end of the light amplifier and outputs adjustable high-frequency impulse signals of 1 GH to 100 GHz. The output end of the light signal test system is connected with the output end of the high-frequency impulse generator. The input end of the feedback control system is connected with the output end of the light signal test system. According to the adjustable high-frequency impulse light source, preparation is compatible with the CMOS technology, the output impulse stability is high, and the anti-interference performance is good.

Low-power sensor signal monitoring and impulse radio architecture for biomedical applications

Abstract: Remote diagnostics of the vital information of a patient and the initiation of necessary actions by the healthcare professionals have resulted in the development of wireless body area network (WBAN). With little to no maintenance, each sensor node within a WBAN must operate with less than 100 μW of power consumption. Impulse radio architecture can be utilized to achieve this goal. This paper reports a low-power transmitter unit consisting of a Data Generator Block, an Impulse Generator Block and a Buffer. The Data Generator Block converts any electrochemical sensor current ranging from 0.2 to 2 μA to digital data. This block consumes a power in the range of 2.575---4.29 μW. The Impulse Generator Block utilizes an RC network to generate impulses of approximately 55 ns duration. Both the Data Generator Block and the Impulse Generator Block can operate with a 1 V supply. Finally, a Buffer circuit, which operates with a 2 V supply, is used to drive a standard 50 Ω load such as an external antenna. The peak current consumption of the impulses is 2.11 mA with a peak output voltage of 72 mV, making it extremely suitable for short range wireless communication. The entire system has been designed and fabricated using a 90 nm standard CMOS process. The average power consumption of the system is only 22.10 μW.

Electrical parameters of water at lightning impulse

Abstract: This paper deals with the description of the behavior of water at lightning impulses. The electric potential distribution in water at lightning impulses is simulated for the calculation of the safe distance. There are not hazardous conditions to human body at distances greater than the safe distance. The examples are swimming pools or water where people are bathing. In these simulations is considered a constant conductivity of the water at impulse current of lightning. But conductivity is not constant value, it change over time and with the instantaneous value of the current passing through. So the main benefit of this article is a description of change in the behavior of the water conductivity.