A rracticaj ntudy of an electromagnetic interference (EMI) problem from Saudi Arabia

Electromagnetic Field interference caused by electric power lines sharing the same corridor with pipelines can produce the unsafe operation of the protection and measuring systems of the pipeline under both normal and faulty conditions. Voltages can be induced on the pipelines from power lines in the areas where they run in parallel together. These voltages vary with the electrical characteristics and geometry of both systems. These voltages can affect the operating personnel, pipeline associated equipment, cathodic protection and the pipeline itself. Mitigation is required to reduce the voltage levels to limit that adverse effect for personnel and pipeline.

Conventional methods used to analyze the inductive interference between electric power lines and pipelines are usually based on a circuit model approach. In the computation of the line parameters in the circuit model approach, the lines are assumed to be parallel and infinite in length. When they are not parallel, a piece-wise parallelism approach is employed. Obviously, these assumptions lead to inaccuracy in the computation of inductive interference. The objective of this paper is to evaluate the level of inaccuracy introduced by the use of these assumptions. To carry out this task, a field approach and a circuit approach are used. The field approach is based on electromagnetic field theory, which does not assume the lines to be parallel and infinite in length and therefore gives accurate results. By comparing the results from the two approaches for different line lengths and different angles between conductors, the error caused by the assumptions used in the circuit model are revealed. Generally, the inductive interference computed using the circuit model approach is higher than that computed using the field theory approach. The results presented in this paper can be used as guidelines to evaluate the accuracy level corresponding to the assumptions made in the computation of inductive interference using the circuit model approach.

High voltage transmission lines may pass through crowded places, and due to the right of way rules high voltage transmission lines forced to share the same corridors with metallic gas pipelines, causing an induced voltage over the metallic pipelines by the mean of electromagnetic fields. This paper presents a study for calculating the electromagnetic field interference between high voltage power lines and nearby metallic gas pipelines for a practical case by using Alternative Transients Program (ATP) simulation and the results are verified by mathematical equations, and evaluate the interference during normal and abnormal conditions by consideration factors such as tower phase arrangement, the existence of sky wires, unbalanced load and fault conditions. The simulation results show that the fault conditions have much higher induced voltage more than any other factors and also show the advantage of Low Reactance Bundle (LR) phases arrangement in reducing the pipeline induced voltage.

Transmission lines are the major source of electromagnetic field interference (EMFI) with metallic structures such as pipelines, railways and under ground cables laying in the same corridor. It is a serious problem because the (EMFI) produces induced voltages on the metallic structures .These voltages can result in hazard volt to operating personnel especially who operate on pipelines .It can affect the pipeline associated equipment (cathodic protection , damage the coating , affect the pipe itself and furthermore will produce corrosion). This paper discusses the study for inductive interference between pipeline and neighboring electrical transmission line .It is especially used to simplify and to automate the modeling for right-of-way configuration involving transmission line and pipeline .It can calculate the voltage on pipeline and the longitudinal current. A practical case study of inductive interference between a pipeline and electrical power line under steady state condition is illustrated.

Conventional methods used to analyze inductive interference between electric power lines and neighboring utilities, such as pipelines, railway, and communication lines, are usually based on a circuit model approach. This approach requires that the line parameters of the entire network be computed first, based on an algorithm in which all conductors are assumed to be parallel. When they are not parallel, a piece-wise parallelism approximation is employed. The objective of this paper is to evaluate the accuracy of this approximation, by comparing its predictions with those of a considerably more accurate electromagnetic field theory approach. Various angles are examined, for both load and fault conditions. The accuracy of the circuit approach appears to be good during load conditions, while it increases considerably for a fault occurring at a power line/pipeline crossing, in which case the interference computed with the circuit approach is higher than that computed using the field approach. This paper documents the accuracy of the piece-wise parallel approximation made in the circuit model approach, for representative system conditions and geometries.

A new analytical model for predicting electromagnetic interference from corona on electric power lines has been developed. The corona is modeled as electric dipoles located on the surface of the power line conductor which is located above a homogeneous lossy Earth. The position and driving current of each dipole are described statistically. Expressions are found for the spectral density of the fields radiated by the corona and the currents induced on the power line. The main contribution of the new model is that it is valid in frequency ranges (i.e., 2–30 MHz) for which no model presently exists and for distances and directions from the power line which are essentially unrestricted. The model is shown to agree well with an empirical formula which was developed from the limited experimental data available.

Conducted EMI in Inverters with SiC Transistors

Chapter 5 - Signal Wiring

Electromagnetic effect of lightning return stroke to buried energy pipelines

Inductive coupling on metallic pipelines: Effects of a nonuniform soil resistivity along a pipeline-power line corridor

The paper defines the term electrical noise with its types. Electromagnetic Interference (EMI), which is one type of electrical noise, is also defined and general techniques used for controlling EMI are described. Networking cables are affected by the EMI effect caused by a nearby power cable and data transmission through Unshielded Twisted Pair (UTP) cable, which is the mostly effected cable by EMI, may be degraded for it. Today, UTP cable is the most popular networking cable supporting 10G Ethernet. The most common effective methods for reduction of EMI effect on UTP cable, physical separation and use of shielding are described. EMI is caused by coupling mechanisms between source of interference and receptor. The two types of couplings are capacitive coupling and inductive coupling. The paper analyses and models the two couplings using lumped circuit components and electric circuit analysis considering power cable as the source of interference and networking cable as the receptor circuit of EMI.

The most common solution for modern adjustable speed drives is the use of induction motors fed by voltage-source inverters. The inverters using fast switching insulated gate bipolar transistors (IGBTs) generate pulse-width modulated (PWM) voltage pulses. The high carrier frequency along with fast rise and fall time of the PWM switching results in nontrivial common-mode or ground currents noise. The current component can cause electromagnetic interference (EMI) noise to neighbour equipments and installations by either radiation from the motor cable or by cross-talk (inductive and capacitive coupling) with other conductors. This paper discusses the inductively coupled EMI noise from an ac drive system where there susceptible devices and a common ground plant are presented. The model describing the sophisticated EMI phenomenon is proposed and measurement results are presented.

12 - An introduction to the analysis of electrical interference from power lines to metal pipelines

In this paper, electromagnetic interferences (EMI) occurred in electric power and telephone lines due to radiation at a frequency of 525 kHz from an aeronautical radio navigation station are presented. The induced voltages measured on those lines caused malfunction or even damage to some electrical devices inside the station. To understand those EMI effects further, an FDTD software package, XFDTD, was applied to evaluate the induced voltages. It was found that the major reasons resulting in interferences were due to longitudinally induced voltages and ground potential rises. They were caused by the radiation from the antenna of the station and current flowing through the ground grids, respectively. In addition, mitigation of EMI was performed to correct those problems by applying separate grounding systems, shielding the telephone, and using underground cables instead of overhead lines near the station. Currently, the whole system, including electric power, navigation and telephone, inside the station operates normally

In order to research the electromagnetic interference (EMI) in substation, this paper describes constitution of analysis model of EMI in substation secondary cable via which EMI can couple to substation secondary system. Substation cable is modeled by transmission line theory and calculated by finite difference time domain (FDTD) method. External electromagnetic field, lightning strike and busbar interference voltage are used to express EMI sources in their models. On this basis, simulation of every model is done and a few examples are calculated.