An investigation of induced voltages to an underground gas pipeline from an overhead transmission line

This paper investigates induced voltage characteristics from an overhead transmission line by applying a method of modeling of induced voltages proposed by the authors. EMTP simulation results obtained by the modeling method agree with analytical results obtained from a well‐known formula. The induced voltages are significantly dependent on the configuration of the overhead line. A horizontal line induces the largest voltage in a gas pipeline, and the voltage induced by a vertical twin‐circuit line is about 20% smaller than that induced by a vertical single‐circuit line. The method is applied to a real pipeline system and the simulation results show reasonable agreement with field test results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 43–51, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20465     

A Study of Mutual Coupling between Vertical Grounding Electrodes

This paper investigates the mutual grounding impedance between vertical grounding electrodes based on field measurements and FDTD simulations. In the case of vertical electrodes, the mutual impedance between the electrodes is almost completely independent of the electrode length, and thus the induced voltage is nearly constant as the electrode length becomes longer. This characteristic is different from that of an overhead conductor, where the electromagnetic‐induced voltage is proportional to the conductor length. The greater the separation distance between the electrodes, the smaller the induced voltage, as in the case of an overhead conductor. The propagation speed increases as the separation increases. It is found that the speed is not necessarily proportional to the inverse of the relative permittivity of the earth.     

Four-terminal parameter formulation of solving induced voltages and currents on a pipeline system

An analytical method of calculating steady-state induced voltages and currents on a complex pipeline system based on a four-terminal parameter has been developed. The developed method makes it very easy to deal with and at the same time to understand the effect of the system parameters, inducing currents and boundary conditions that are different in each section of the pipeline system. Analytical results show that there exists a position where the pipeline voltage to ground becomes zero. When both ends of the pipeline are grounded through a resistance, the position of the zero potential is nearly the centre of the pipeline. If one end is open-circuited, the other end shows zero potential. This fact has not been well recognised by engineers in this field. Also, the effect of the inducing currents, which are different in each section along the pipeline, is explained from the physical viewpoint based on the analytical results. The accuracy of the proposed method is confirmed to be satisfactory in comparison with Electromagnetic Transients Programme (EMTP) simulation and field test results.     

Digital fault location for high resistance grounded transmissionlines

This paper demonstrates that the presence of multiple load taps cannot be neglected for single-phase-to-ground fault location. A new method has been developed taking this into consideration, that can be applied to correct the location error due to intermediate power sources. Then fault location methods for parallel double-circuit two-terminal transmission lines are discussed. Finally, a new fault location method is proposed for high-resistance grounded double-circuit transmission lines with three terminals     

Determinant analysis of IgE and IgG4 antibodies and T cells specific for bovine alpha(s)1-casein from the same patients allergic to cow's milk: existence of alpha(s)1-casein-specific B cells and T cells characteristic in cow's-milk allergy

In an effort to clarify the etiology of milk allergy from the standpoint of allergen-specific immune reactions, we investigated the determinants of IgE, IgG4, and T cells specific for bovine alpha(s)1-casein from the same individual patients by using its synthetic peptides and cyanogen bromide-digested fragments. Alpha(s)1-casein is a major allergen in cow's milk, and its unique conformation enabled us to investigate the determinants of antibodies without consideration about missing the reactivities because of conformational changes. Nine patients were selected as subjects from among 129 milk-sensitive infants screened by ELISA to assess the anti-alpha(s)1-casein IgE levels in their sera. By using ELISA for epitope mapping, a C-terminal region of alpha(s)1-casein was identified as a common binding site for IgE from all of these patients, whereas those for anti-alpha(s)1-casein IgG4 were located in multiple regions of alpha(s)1-casein. We determined the specificities of seven alpha(s)1-casein-specific T-cell lines established from peripheral blood mononuclear cells of two of the patients. These T cells have been shown to secrete IL-4. All of the T-cell lines had different specificities to alpha(s)1-casein. However, a common amino acid residue use was found among the determinants of various T-cell lines from each patient. The results suggest that patients allergic to cow's milk have characteristic B cells recognizing a limited region of alpha(s)1-casein and secreting alpha(s)1-casein-specific IgE. These B cells may interact particularly with T cells recognizing determinants with a common structure.     

An Improved Thin Wire Representation for FDTD Computations

We have shown that finite-difference time-domain (FDTD) electromagnetic computations for a conductor system having a radius smaller than 0.15Deltar or larger than 0.65 Deltar (Deltar is the lateral side length of cells employed), modeled using arbitrary-radius-wire representations proposed so far with a time increment determined from the upper limit of Courant's stability condition, result in numerical instability. A primary factor causing this numerical instability is that the speed of waves propagating in the radial direction from the wire in the immediate vicinity of the wire exceeds the speed of light, and therefore, Courant's condition is not satisfied there. It is further shown that for these cases, the arbitrary-radius-wire representation can be improved by modifying the material parameters for the axial field components closest to the wire as well as those for the radial electric and circulating magnetic field components. The improved wire representation is effective in representing a wire whose radius ranges from 0.0001Deltar to 0.9Deltar.     

Application of the partial element equivalent circuit method to tower surge response calculations

This article presents calculations of tower surge responses and insulator voltages of an actual transmission tower including ground wires and phase wires. The partial element equivalent circuit (PEEC) method is applied as a simulation tool. Surge responses of the tower and insulator voltages calculated by the PEEC method are compared with electro magnetic transients program (EMTP) simulated results and experimental results collected from the literatures. The results calculated by the PEEC method agree well with the experimetal results, not only amplitudes but also waveshapes. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Theoretical analysis of transient recovery voltages when clearing a transformer secondary fault

An analytical formula for the transient recovery voltage and its derivative dv/dt across a circuit breaker has been derived for the case of a transformer secondary fault. A comparison of the calculated results with field test and EMTP simulation results has demonstrated it to have satisfactory accuracy. By applying the formula, the effects of various circuit parameters on the transient recovery voltage and its derivative dv/dt are elucidated. The derivative dv/dt, defined conventionally as the ratio of the crest value and the time to the crest, is found to be about two‐thirds of the maximum value of dv/dt given as a function of time. In addition, a formula for the critical circuit parameters at which dv/dt across a vacuum circuit breaker reaches the critical condition, that is, the circuit breaker fails to interrupt a fault current, is derived. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 44–52, 2001     

Field test and EMTP simulation of transient voltages when clearing a transformer secondary fault

A field test was carried out to investigate a fault clearing transient due to current interruption of a three‐phase to ground fault at the secondary side of a 3‐MVA, 22/6.6‐kV transformer by a vacuum circuit breaker. EMTP simulations in comparison with the measured results have made it clear that the capacitance C_p of a CR divider to measure voltages reduces dv/dt of transient recovery voltage across the circuit breaker by the ratio of (C_t/(C_t + C_p) where C_t is the transformer stray capacitance. The leakage inductance evaluated from the transformer rating has been found to be noticeably greater than that determined from the measured fault current possibly due to the transformer saturation. Considering the transformer magnetizing conductance and selecting an appropriate interrupted current, EMTP simulation gives a satisfactory result compared with a field test. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 40–48, 2000