Contact voltage modeling for electrical installation bodies with phase-to-ground fault in open pit mines

The newly developed MatLab Simulink-based model allows simulating processes in earthing systems in open pit mines and quarries, in case of phase-to-ground fault (PGF) in 6 (10) kV power grids and in case of current drainage in low-voltage grids. The processes in the earthing systems at a typical open pit mine site with a substation, a shovel, a mobile low-voltage substation, a drill, and an air cable line are modeled. The model represents the schematic of the power network with insulated neutral as two interrelated systems of feed and earthing. The feed system is composed of transformers, conductors and electric installations with grounded phase conductors. The earthing system consists of the principal earthing of the substation, main aerial earthing lines and cable earthing, local earthing devices of the switching substation and low-voltage substation, and of auxiliary earthing when metal bodies of the electrical installations contact soil. The contact voltages and currents in earth leads are modeled. It is found that phase-to-ground fault current equals the sum of all currents in all earthing lines, namely, in principal, local and auxiliary earth leads. The contact voltages depend on the values of PGF currents and earth-connection resistances. The increase in the PGF currents with resistive neutrals for the reliable operation of the maximum current protections elevates the contact voltages by 4 times and more. Violation of the earthing system integrity, for instance, in breakage of earthing cable, greatly escalates the contact voltage at the bodies of all electrical equipment in an open pit mine.

Keywords: open pit mining power supply, phase-to-ground fault, earthing system, modeling contact voltages and current voltages.
For citation:

Lyakhomskii A. V., Gerasimov A. I. Contact voltage modeling for electrical installation bodies with phase-to-ground fault in open pit mines. MIAB. Mining Inf. Anal. Bull. 2021;(12):169-178. [In Russ]. DOI: 10.25018/0236_1493_2021_12_0_169.

Acknowledgements:
Issue number: 12
Year: 2021
Page number: 169-178
ISBN: 0236-1493
UDK: 621.316.99:004.942
DOI: 10.25018/0236_1493_2021_12_0_169
Article receipt date: 30.07.2021
Date of review receipt: 01.09.2021
Date of the editorial board′s decision on the article′s publishing: 10.11.2021
About authors:

A.V. Lyakhomskii1, Dr. Sci. (Eng.), Professor,
A.I. Gerasimov1, Cand. Sci. (Eng.), Assistant Professor, e-mail: mggu.eegp@mail.ru,
1 National University of Science and Technology «MISiS», 119049, Moscow, Russia.

 

For contacts:

A.I. Gerasimov, e-mail: mggu.eegp@mail.ru.

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