Transient Electromagnetic Interference Research Articles

A Method to Extract and Eliminate TEM Interference by Metallic Bodies in Tunnel Geological Anomaly Forecast

The transient electromagnetic (TEM) method is a geophysical exploration technique used in a wide range of applications such as mineral exploration, hydrogeology surveys, and underground geological mapping. In recent years, it has been applied in tunnel construction to forecast geological anomalies in front of the excavation face. However, the TEM response can be affected by metallic objects such as excavation carts and metallic support structures, which makes interpretation more difficult. The purpose of this study is twofold: to introduce a new method for extracting and eliminating TEM interference from metallic bodies in a tunnel excavation environment and to gain insight regarding the influence of metallic objects on the TEM response by physical modeling in the laboratory and studies conducted in the field. The concept of resistive limits is introduced; these limits can be used as eigenvalues in the inversion process, thus achieving more accurate identification of both the location and size of ball-shaped, low-resistivity anomalies (gouge materials) in surrounding rock that has high resistivity. Both the physical laboratory simulations and the field experiments provide insight on the interference effect of metal objects such as a steel arches or excavation carts on the TEM response. Field experiments inside a tunnel indicate that the maximum distance between the excavation cart tested and the tunnel face that can influence the TEM response is 30 m, while the maximum influence distance of a steel arch is 1 m in the vertical plane of the coil and 2 m in the axial direction. The proposed inversion process was shown to be capable of extracting the interference of metallic objects from TEM responses and improve the accuracy of TEM interpretation in identifying geological anomalies.

Measurement of transient electromagnetic coupling and interference caused by disconnector operation in substation

Abstract Disconnector operation in the substation can cause transient electromagnetic disturbance and very fast transient over-voltage (VFTO), and will lead to the misoperation or damage of electrical protection system. To research the characteristics and influence of electromagnetic interference, principle of disconnector operation was analyzed. Then, an improved Agrawal model was adopted to describe the transmission line coupling process of disconnector operation, and telegraph equation was calculated by finite-difference time-domain (FDTD) method. With the model and method, the conduction process and characteristics of transient electromagnetic coupling and interference caused by disconnector operation in substation were simulated. Besides, disturbance voltage signal on the secondary cables caused by disconnector operation was measured in a 500 kV substation. Finally, parameters of transient electromagnetic coupling and interference in time domain and frequency domain were calculated respectively. Experiment results show that the quantitative level of transient electromagnetic coupling and interference caused by disconnector operation in substation can be evaluated in theory, and the core frequency points concerned in secondary circuit can be calculated.

Mitigation of switching‐induced transient electromagnetic interference on control cable using Ni–Zn ferrite rings over cable sheath in gas‐insulated substations

AbstractThe transient electromagnetic fields during switching operation in gas‐insulated substations (GISs) have rise times on the order of nanoseconds. These fields leak into the external environment through the discontinuities of gas‐insulated modules and affect the control cables and induce the transient voltage on cables, which results in malfunctioning of the equipment. The amplitudes of the electric and magnetic fields could be a few tens of kilovolts per meter and a few hundred amperes per meter according to layout of GIS, respectively. In this work, the induced voltage in the central conductor of a control cable and the induced current in its sheath, which is parallel to bus duct in a GIS with rated voltage of 230 kV, are calculated. Influence of the sheath material on the induced voltage and the type of its grounding on the induced current are analyzed. Furthermore, the impact of installing ferrite rings over the control cable sheath in mitigating the induced voltage and current is investigated. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Application of Near-Field Emission Processing for Microwave Circuits under Ultra-Short Duration Perturbations

This paper is dealing with a time-frequency modeling method of electromagnetic (EM) near-field (NF) radiated by electronic devices excited by transient pulse signals. The model developed enables to calculate the EM NF maps at different distances from the given device and also the synthesis of radiation sources enabling to reproduce the field maps. The method proposed is based on the ultra wide band (UWB) frequency model of EM NF maps. The number of EM NF maps can be reduced by considering an innovative algorithm in order to establish simply the dipole model. Then, the transient model can be realized by considering the convolution between the transient excitation signals and the dipole-array model. The method proposed was validated by a standard 3D EM tool with a planar microstrip device excited by microwave signal modulating 1.25-GHz-carrier with 0.5-GHz-bandwidth. As expected, good correlation is found between results from simulation and the investigated modelling method. The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs).

Calculations of near-field emissions in frequency-domain into time-dependent data with arbitrary wave form transient perturbations

This paper is devoted on the application of the computational method for calculating the transient electromagnetic (EM) near-field (NF) radiated by electronic structures from the frequency-dependent data for the arbitrary wave form perturbations i(t). The method proposed is based on the fast Fourier transform (FFT). The different steps illustrating the principle of the method is described. It is composed of three successive steps: the synchronization of the input excitation spectrum I(f) and the given frequency data H0(f), the convolution of the two inputs data and then, the determination of the time-domain emissions H(t). The feasibility of the method is verified with standard EM 3D simulations. In addition to this method, an extraction technique of the time-dependent z-transversal EM NF component Xz(t) from the frequency-dependent x- and y- longitudinal components Hx(f) and Hy(f) is also presented. This technique is based on the conjugation of the plane wave spectrum (PWS) transform and FFT. The feasibility of the method is verified with a set of dipole radiations. The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs).

Impact of Switching-Induced Electromagnetic Interference on Low-Voltage Cables in Substations

The electromagnetic environment within a substation is very complex. Substations represent an intricate interconnected collection of devices that serve as electromagnetic wave emitters and receptors. Transient electromagnetic emissions-electromagnetic interference (EMI)-are generated during the switching of disconnector and circuit breakers (CBs) that may cause malfunction or damage to electronic equipment positioned nearby if appropriate immunity measures are not taken. The interference may couple significant energy through common-mode currents to cable protection. Electromagnetic compatibility is mostly achieved by addressing the EMI victim through techniques in the secondary environment, such as shielding and filtering. This paper presents the finite-element method analysis of three methods: metallic channel, braided cable, and additional cable, used for EMI mitigation on low-voltage cables of 20 kV side in a 63-kV/20-kV substation due to switching effects of disconnector and CBs. In each method, overvoltage is considered and the results are compared with each other. A simple circuit analysis was also carried out on the causes of switching based on EMI to provide some insight into the interference mechanism during switching process, using common-mode and differential-mode equivalent circuits. The overvoltage reductions are attained through differential-mode current and shielding methods.

Determination of Parameters in the Universal Induction Motor Model

A systematic procedure to determine the parameters of a previously proposed low- to high-frequency induction motor model is presented. An analysis of the high-frequency behavior with regard to the impact of magnetic core selection, parasitic interturn and winding-to-frame capacitors, and skin effects of windings is investigated in greater detail for the proposed universal model of an induction motor. The model is universal in the sense that it is derived by extending the low-frequency standard T-equivalent circuit (IEEE Standard 112) to include high-frequency effects under both common- and differential-mode domains and can be used for transient reflected-wave studies and electromagnetic interference emissions in motor drive systems. A test-based method and an analytical approach, which are useful in application and design stages, respectively, are presented to determine the frequency characteristics of the induction motor. Findings of the investigation were verified experimentally with results presented in this paper.

On the Effects of Transient Electromagnetic Interference on Integrated Circuits

Abstract The susceptibility of ICs to electromagnetic interference is a growing concern for both designers and failure analysts. This article discusses the causes and effects of transient electromagnetic interference and the factors that influence electromagnetic susceptibility. It explains how to determine susceptibility based on transient pulse testing and presents and interprets the test results of three automotive ICs.

Shielding of Electronic Systems against Transient Electromagnetic Interferences

Abstract. In order to protect electronic systems against the effects of transient electromagnetic interferences, shields made of electrically conductive material can be used. The subject of this paper is an electrically conductive textile. When applying the shield, a reliable measure is needed in order to determine the effectiveness of the shield to protect against electromagnetic pulses. For this purpose, a time domain measurement technique is presented using double exponential pulses. With these pulses, the susceptibility of an operating electronic device with and without the shield is determined. As a criterion of quality of a shield, the breakdown failure rate found in both cases is compared.

A two-level plane wave time-domain algorithm for fast analysis of EMC/EMI problems

A fast time-domain integral equation (TE)-based scheme for analyzing transient electromagnetic compatibility and interference (EMC/EMI) problems involving printed circuit boards and cables/connectors that reside in shielding enclosures, is presented. The proposed algorithm hybridizes a classical marching-on-in-time (MOT) solver for analyzing radiation from perfect electrically conducting (PEC) surface/wire geometries with the previously introduced two-level plane wave time-domain (PWTD) algorithm. The accuracy and efficacy of the resulting MOT-PWTD algorithm are validated via analysis of the radiation characteristics of a number of structures including a loaded motherboard that resides in a chassis. For a problem with N/sub s/ spatial and N/sub T/ temporal unknowns, the computational complexity of the two-level MOT-PWTD algorithm scales as O(N/sub T/N/sub S//sup 1.5/ log N/sub S/) as opposed to O(N/sub T/N/sub S//sup 2/) for a classical MOT scheme.

Measurement technique developed to evaluate transient EMI in a photo bay

A new technique for quantifying the magnitude and the rate of ESD-induced transient electromagnetic interference (ESD-EMI) was developed. The developmental steps taken leading up to histograming of the peak-to-peak voltage of the multiple EMI transients as a measurement technique are presented as motivation for the technique. An application of this technique is presented with EMI rate measurement results with and without ionization in Photobay 2 at International SEMATECH. The rate of ESD-EMI events recorded in the bay was 30 times greater with the ionizers off than with them on. The technique uses a very high sampling rate (4 GS/s) digitizing oscilloscope, with a wide bandwidth (>1.5 GHz), and a histogram technique to acquire a spectrum of amplitudes of the transient events.

A study of the mechanisms for ESD damage to reticles

Reticles were exposed to the fringing field from an electrode biased to a high voltage. The reticles in the study included reticles designed to benchmark the electrostatic damage (ESD) hazard of photobay and production reticles of a variety of feature sizes. It was found that without any electrical contact between the reticle and the electrode, reticle damage could be done. A wide bandwidth transient-electromagnetic interference (EMI) sensing antenna revealed that the reticle sparked when a voltage as low as 2000 V was applied to the electrode. The tests showed that the ESD threshold of reticles with smaller feature sizes was lower than for reticles with larger feature sizes. Reticles were scanned under optical and atomic force microscopes for reticle damage. It was found that when the voltage was ramped to 17 kV and returned to zero, damage to the reticle was observed. When a voltage of 7.5 kV was applied once, no damage was observed but when it was applied 100 times, reticle damage was observed. This study confirms that ESD damage is done to a reticle by charged objects in the vicinity of the reticle in contrast with the prevailing belief that reticle damage is done only by charge on reticles. The study also showed that reticles can be sufficiently damaged to cause printing errors due to the accumulated damage caused by repeated low level exposure to the fringing field of a charged object in the vicinity of the reticle.

Lumped Element Model for Spacecraft Surface Charging Studies

The external surfaces of a spacecraft exposed to Earth's magnetospheric plasma can build up differential voltages which can result in an electrostatic discharge (ESD). This discharge may induce transient electromagnetic interference (EMI) in the electronics circuitry and may give rise to switching anomalies or system failure under certain environmental conditions. This paper outlines the development of Lumped Element Model (LEM) of a spacecraft for surface charging studies. A numerical solution procedure using method of moments and triangular patch modelling to determine the capacitance of conducting objects in free space has been developed. Differential equations of spacecraft charging have been derived and the surface charging of INSAT-2E spacecraft has been simulated. The results obtained for INSAT-2E using LEM concept are compared with those obtained using the NASA Charging Analysis Program (NASCAP) for a similar satellite.Using LEM of a conducting plate located in free space, and with the help of circuit simulation software, the transient structural current due to a blow-off discharge is predicted. Power supply lines, command and control lines, lines connected to antenna probes, switches and thence to microwave devices can pick up ESD transients. Hence ESD immunity should be built into microwave subsystem as well. Techniques of hardening microwave subsystem against on-board ESD have also been outlined.

Measurement of the electromagnetic environment of HVDC converter stations

The results of an experimental study on the electromagnetic environment of HVDC (high-voltage direct-current) converter stations are presented. Transient EMI (electromagnetic interference) as well as steady-state RI (radio interference) and TVI (television interference) measurements were made at the Arnott station of BC Hydro and the Chateaguay station of Hydro-Quebec. The maximum values of the electric and magnetic fields measured inside the valve halls of Arnott station are 1.8 kV/m and 3.2 A/m; outside, they are 0.28 kV/m and 0.4 A/m respectively. These values cover the range of normal operation, including start-up and stopping of the converter station. During normal operation of the Chateauguay station, maximum electric and magnetic fields of 0.7 kV/m and 1.1 A/m are measured inside the valve hall; outside, they are below the sensitivity of the measuring system. It is recommended that immunity testing be carried out on electronic equipment to be used either inside or outside the valve halls of converter stations at transient electric and magnetic field levels of 5 kV/m and 10 A/m, respectively, with approximately 1 mu s risetime and 10 mu s duration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Measurement of the Electromagnetic Environment of HVDC Converter Stations

The results of an experimental study on the electromagnetic environment of HVDC (high-voltage direct-current) converter stations are presented. Transient EMI (electromagnetic interference) as well as steady-state RI (radio interference) and TVI (television interference) measurements were made at the Arnott station of BC Hydro and the Chateaguay station of Hydro-Quebec. The maximum values of the electric and magnetic fields measured inside the valve halls of Arnott station are 1.8 kV/m and 3.2 A/m; outside, they are 0.28 kV/m and 0.4 A/m respectively. These values cover the range of normal operation, including start-up and stopping of the converter station. During normal operation of the Chateauguay station, maximum electric and magnetic fields of 0.7 kV/m and 1.1 A/m are measured inside the valve hall; outside, they are below the sensitivity of the measuring system. It is recommended that immunity testing be carried out on electronic equipment to be used either inside or outside the valve halls of converter stations at transient electric and magnetic field levels of 5 kV/m and 10 A/m, respectively, with approximately 1 mu s risetime and 10 mu s duration. >