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Title: Self-Shielding Of Transmission Lines

Abstract

The use of shielding to contend with noise or harmful EMI/EMR energy is not a new concept. An inevitable trade that must be made for shielding is physical space and weight. Space was often not as much of a painful design trade in older larger systems as they are in today’s smaller systems. Today we are packing in an exponentially growing number of functionality within the same or smaller volumes. As systems become smaller and space within systems become more restricted, the implementation of shielding becomes more problematic. Often, space that was used to design a more mechanically robust component must be used for shielding. As the system gets smaller and space is at more of a premium, the trades starts to result in defects, designs with inadequate margin in other performance areas, and designs that are sensitive to manufacturing variability. With these challenges in mind, it would be ideal to maximize attenuation of harmful fields as they inevitably couple onto transmission lines without the use of traditional shielding. Dr. Tom Van Doren proposed a design concept for transmission lines to a class of engineers while visiting New Mexico. This design concept works by maximizing Electric field (E) and Magneticmore » Field (H) field containment between operating transmission lines to achieve what he called “Self-Shielding”. By making the geometric centroid of the outgoing current coincident with the return current, maximum field containment is achieved. The reciprocal should be true as well, resulting in greater attenuation of incident fields. Figure’s 1(a)-1(b) are examples of designs where the current centroids are coincident. Coax cables are good examples of transmission lines with co-located centroids but they demonstrate excellent field attenuation for other reasons and can’t be used to test this design concept. Figure 1(b) is a flex circuit design that demonstrate the implementation of self-shielding vs a standard conductor layout.« less

Authors:
 [1]
  1. Univ. of New Mexico, Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1347887
Report Number(s):
SAND-2017-2838R
651775
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING

Citation Formats

Christodoulou, Christos. Self-Shielding Of Transmission Lines. United States: N. p., 2017. Web. doi:10.2172/1347887.
Christodoulou, Christos. Self-Shielding Of Transmission Lines. United States. doi:10.2172/1347887.
Christodoulou, Christos. Wed . "Self-Shielding Of Transmission Lines". United States. doi:10.2172/1347887. https://www.osti.gov/servlets/purl/1347887.
@article{osti_1347887,
title = {Self-Shielding Of Transmission Lines},
author = {Christodoulou, Christos},
abstractNote = {The use of shielding to contend with noise or harmful EMI/EMR energy is not a new concept. An inevitable trade that must be made for shielding is physical space and weight. Space was often not as much of a painful design trade in older larger systems as they are in today’s smaller systems. Today we are packing in an exponentially growing number of functionality within the same or smaller volumes. As systems become smaller and space within systems become more restricted, the implementation of shielding becomes more problematic. Often, space that was used to design a more mechanically robust component must be used for shielding. As the system gets smaller and space is at more of a premium, the trades starts to result in defects, designs with inadequate margin in other performance areas, and designs that are sensitive to manufacturing variability. With these challenges in mind, it would be ideal to maximize attenuation of harmful fields as they inevitably couple onto transmission lines without the use of traditional shielding. Dr. Tom Van Doren proposed a design concept for transmission lines to a class of engineers while visiting New Mexico. This design concept works by maximizing Electric field (E) and Magnetic Field (H) field containment between operating transmission lines to achieve what he called “Self-Shielding”. By making the geometric centroid of the outgoing current coincident with the return current, maximum field containment is achieved. The reciprocal should be true as well, resulting in greater attenuation of incident fields. Figure’s 1(a)-1(b) are examples of designs where the current centroids are coincident. Coax cables are good examples of transmission lines with co-located centroids but they demonstrate excellent field attenuation for other reasons and can’t be used to test this design concept. Figure 1(b) is a flex circuit design that demonstrate the implementation of self-shielding vs a standard conductor layout.},
doi = {10.2172/1347887},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

Technical Report:

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  • The Fortran IV code PAPIN has been developed to calculate cross section probability tables, Bondarenko self-shielding factors and average self-indication ratios for non-fissile isotopes, below the inelastic threshold, on the basis of the ENDF/B prescriptions for the unresolved resonance region. Monte-Carlo methods are utilized to generate ladders of resonance parameters in the unresolved resonance region, from average resonance parameters and their appropriate distribution functions. The neutron cross-sections are calculated by the single level Breit-Wigner (SLBW) formalism, with s, p and d-wave contributions. The cross section probability tables are constructed by sampling the Doppler-broadened cross sections. The various self-shielded factors aremore » computed numerically as Lebesgue integrals over the cross section probability tables. The program PAPIN has been validated through extensive comparisons with several deterministic codes.« less
  • Magnetically self-insulated lines operating at high electric field stress have a high percentage of the current flow in an electron sheath adjacent to the cathode. Recovery of the current in this sheath is desirable for efficient power transport. The Sandia National Laboratories HydraMITE accelerator has a magnetically insulated transmission line which has a 7.6 ..cap omega.. geometric impedance, and operates at 4.8 ..cap omega.., indicating that approximately 40% of the current flows in the electron sheath. An experiment was conducted on the HydraMITE machine in which input and output currents were measured on a section of line which the impedancemore » changed smoothly from 7.6 ..cap omega.. to 20 ..cap omega... Measurements were made with a range of inductive and resistive loads. The input and output currents were then compared to lumped circuit line simulations to separate losses related to inductance from electron sheath losses.« less
  • Existing cold fluid theories for magnetic insulation are analyzed and applied to the transmission line configuration. The relevance of these results to the propagating short pulse problem, and to DC operation, are discussed.
  • Various pumping arrangements and their pressure profile control for forced cooling of long pipe-type transmission lines were investigated. The system was separated into a number of units where the oil flow direction alternated from unit to unit. Experimentally and analytically it was determined that pump systems operating as constant flow sources were superior to constant pressure sources and that the even-number-of-units configuration was the best solution when operated with a single pressure control head tank. The simplest line pressure profile control appeared to be the pump bypass, the head tank pressure adjustment, however was the most effective line pressure profilemore » control scheme. The electric analogy model tests showed that, for all practical imbalance sizes, either of these methods alone was sufficient to maintain the line pressure profile within its working limit, and that, to extend the range of these controls, the control should be based on the pump discharge, rather than the pump inlet pressure.« less
  • The heat dissipated in the conductor of a forced cooled pipe-type cable must pass through two thermal resistances in series: the conduction resistance of the cable insulation and the convection resistance due to forced and natural convection from the cable surface to the oil. The upper limit to the convection resistance was determined by natural convection heat transfer tests on a full scale model of a pipe-type cable system. It was found that conduction resistance is more than four times larger than convection resistance from cables designed for 138 kV and higher voltages. Therefore, to accurately predict the temperature insidemore » the cable for a given oil temperature and current, a precise prediction of convection heat transfer is necessary. The solution for conduction within the cable must include effects due to cable splices and the proximity of one cable to another.« less