scholarly journals Voltages Induced in Overhead Ground-Wire Cable as Risk Factor. Part 1

2016 ◽  
Vol 5 (1) ◽  
pp. 28-40 ◽  
Author(s):  
Токарский ◽  
A. Tokarskiy ◽  
Рубцова ◽  
Nina Rubtsova ◽  
Рябченко ◽  
...  
Keyword(s):  
Risk Factor ◽  
Single Phase ◽  
Interval Length ◽  
Maximum Permissible Level ◽  
Overhead Transmission Line ◽  
Spark Gap ◽  
Three Phase ◽  
Electric And Magnetic Fields ◽  
Short Circuits ◽  
Selection Of

To ensure the staff safety under hot-line overhead transmission line (OTL) maintenance, as well as overhead ground-wire cable (OGWC) insulation integrity maintaining, by the example of three-phase 750 kV OTL has been presented an algorithm for calculation of voltages and electromotive forces (EMF) induced in this line’s OGWC by electric and magnetic fields (EF and MF) generated by OTL phases’ voltages and currents. Algorithms for calculation of line-to-earth voltages distribution along grounded at one end OGWC’ intervals have been given. It has been shown that the voltage induced at OGWC by EF of 750 kV OTL is much less than the voltage induced by this OTL’s MF. For single-phase short circuits modes has been presented an algorithm for selection of grounded at one end OGWC’ interval length by condition of respecting of voltage’s maximum permissible level on a spark gap shunting OGWC’s insulator set.

scholarly journals Modeling Features of a Single Phase-to-Earth Fault in a Medium Voltage Overhead Transmission Line

2020 ◽  
Vol 4 (2) ◽  
pp. 127-138
Author(s):  
Ismael Saeed ◽  
Kamal Sheikhyounis
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Single Phase ◽  
Single Frequency ◽  
Mathematical Representation ◽  
Medium Voltage ◽  
Overhead Transmission Line ◽  
Earth Fault ◽  
Distributed Parameters ◽  
Selection Of

The modeling and calculation of a single phase-to-earth fault of 6 to 35 kV have specific features when compared with circuits with higher nominal voltages. In this paper, a mathematical analysis and modeling of a 3-phase overhead transmission line with distributed parameters consisting of several nominal T-shaped, 3-phase links with concentrated parameters replaced by 1 nominal T-shaped link were carried out. Further analysis showed that not accounting for the distributed nature of the line parameters did not cause significant errors in the assessment of the maximum overvoltage in the arc suppression in single phase-to-earth faults, and that sufficient accuracy insures the representation of the line by only 1 nominal T-shaped, 3-phase link. Such a modeling technique makes it impossible to identify the location of single-phase faults, which is the property of higher harmonic amplification of individual frequencies. Chain equivalent schemas with constant parameters are valid for a single frequency, thereby providing an opportunity to study the nature of the wave process by the discrete selection of parameters. Next in the mathematical representation, we consider the overhead transmission lines as lines with distributed parameters.

The Poynting Vector and the New Theory of a Transformer. Part 11. Three-Phase Three-Core Transformers without a Neutral Wire

2021 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Mansur A. SHAKIROV ◽  
Keyword(s):  
Equivalent Circuit ◽  
Single Phase ◽  
Poynting Vector ◽  
Magnetic Circuit ◽  
Phase Zone ◽  
Field Patterns ◽  
Three Phase ◽  
Short Circuits ◽  
The Difference ◽  
Mathematical Relations

A topological equivalent circuit for a three-phase three-core transformer reflecting the spatial structure of its magnetic system is developed. Owing to this approach, it became possible to represent the magnetic fluxes of the magnetic circuit’s all main sections and the apertures for each of three phases directly in the circuit in the absence of the windings’ neutral wires. The circuit is constructed by stitching together the anatomical circuit models of single-phase transformers obtained in the previous parts with taking into account the relationships between the fluxes at the junctions of the phase zones in iron. Its validity is confirmed by the rigor nature of the physical and mathematical relations for idealized transformers with infinite magnetic permeability of iron and simplified magnetic field patterns, which corresponds to the generally accepted approach with neglecting the magnetization currents. The difference lies in the fact that the developed model takes into account the heterogeneity of magnetization in different parts of the magnetic circuit with allocating more than 30 sections in the iron and apertures. The transition to the model of a real three-core transformer is carried out by adding four nonlinear transverse magnetization branches in each extreme phase zone and eight branches in the central phase zone to the idealized equivalent circuit. It is shown that in cases of winding connections without neutral wires, there is no flux of the Poynting vector in interphase zones in any unbalanced mode. In this case, the problems connected with the occurrence of fluxes exceeding the no-load fluxes under the conditions of symmetric and asymmetric short circuits, as well as the occurrence of buckling fluxes in these modes in the region outside the transformer iron, are solved.

scholarly journals Voltages Induced in Overhead Ground-Wire Cable as Risk Factor. Part 2

2016 ◽  
Vol 5 (2) ◽  
pp. 43-56
Author(s):  
Токарский ◽  
A. Tokarskiy ◽  
Рубцова ◽  
Nina Rubtsova ◽  
Рябченко ◽  
...  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Communication Line ◽  
Voltage Level ◽  
Overhead Transmission Line ◽  
Three Phase ◽  
Fiber Optic Communication Line ◽  
Fiber Optic Communication ◽  
Personnel Safety ◽  
Optic Communication

To ensure the personnel safety during live working on overhead transmission line (OTL), as well as lightning protection cables’ (LPC) isolation integrity maintaining, by the example of three-phase 750 kV OTL has been presented an algorithm for calculation of voltages, electro-moving forces and currents induced by single phase short-circuit currents’ magnetic field of OTL in LPC1 grounded in one point, and in LPC 2 (with fiber-optic communication line function) grounded at every tower. For single-phase short circuit modes has been presented an algorithm for length selection of grounded on one end LPC1 part on the condition of compliance with the maximum permissible voltage level on a spark gap which bypasses an insulator set of LPC1.

Three-phase to Single-phase Matrix Converter for Improvement of Three-phase Voltage Unbalance in Distribution System

2015 ◽  
Vol 135 (3) ◽  
pp. 168-180 ◽  
Author(s):  
Ryota Mizutani ◽  
Hirotaka Koizumi ◽  
Kentaro Hirose ◽  
Kazunari Ishibashi
Keyword(s):  
Distribution System ◽  
Single Phase ◽  
Matrix Converter ◽  
Phase Voltage ◽  
Voltage Unbalance ◽  
Three Phase

About the Selection of a Single-Phase Short-Circuit Current on Earth in the Network With Low-Ohm Resistive Grounding of the Neutral

2017 ◽  
pp. 34-41
Author(s):  
Andrei V. MAIOROV ◽  
◽  
Kirill A. OSINTSEV ◽  
Andrei V. SHUNTOV ◽  
◽  
...  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Selection Of
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