Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage up to 1000 V at Mining Enterprises

The main objectives of this publication are: 1) to attract the attention of energy specialists to the problems of reliability and electrical safety of 6-10 kV overhead electrical networks with isolated neutral, operating in conditions of single-phase insulation damage; 2) substantiation of the feasibility of introducing a fundamentally new way to improve the efficiency of 6-10 kV distribution networks, based on the resonanceless limitation of the single-phase ground fault current arising from the breakdown of the insulator and the use of its own infrastructure of the electrical network for remote identification of the place of its occurrence. The expediency of including a nonlinear surge suppressor between the traverse and the grounding outlet of the reinforced concrete support is confirmed by the positive results of experimental studies carried out on the basis of high-voltage testing laboratories of IDGC of Center PJSC - Orelenergo and EnerGarant LLC. The use of deductive analysis allowed the authors to select a reliable and affordable electrical insulating material installed between the support and the traverse, as well as to formulate the main requirements for it, including taking into account weather and climatic factors. The analysis of various methods of transmitting information about the place of occurrence of the insulator damage made it possible to establish the predominant advantage of a wired communication channel using its own 6-10 kV electric network infrastructure. The authors have developed an original circuitry solution that provides remote identification of the insulator damage location using a thyristor shunting the nonlinear surge suppressor, according to a given switching algorithm, and also provides local identification of the insulator breakdown by means of special signaling devices with volatile power supply. It is expected that the proposed method, with relatively low investment, will significantly reduce the level of accidents and electrical hazards in overhead distribution networks of 6-10 kV, as well as minimize the costs associated with their operation and undersupply of electrical energy.

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Analysis of Circuit Solutions for the Modernization of Distribution Networks for Housing and Communal Services

Известия высших учебных заведений Электромеханика ◽

10.17213/0136-3360-2021-3-75-84 ◽

2021 ◽

Vol 64 (3) ◽

pp. 75-84

Author(s):

Ivan Nadtoka ◽

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Pyotr Osadchy ◽

Vladimir Tropin ◽

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...

Keyword(s):

Integrated Circuit ◽

Low Voltage ◽

Experimental Tests ◽

Distribution Networks ◽

Theoretical Research ◽

Electrical Safety ◽

Power Losses ◽

Average Value ◽

Isolated Neutral

The article presents the results of the analysis of the main stages of the development of electric networks for housing and communal services (HCS) since the 50s of the last century and ending with the latest innovative developments, which are both at the stage of theoretical research and experimental tests in pilot projects implemented in existing networks. It is noted that the traditional 10(6)/0.4 kV structure with a dead-earth neutral on the low-voltage side, which is used both in industrial and utility networks, has disadvantages associated with increased power losses, as well as the need to use special technical means to ensure the required quality of electricity. It is shown that with the average value of the reverse sequence current coefficient equal to 0.3, the relative value of additional power losses in the low-voltage line from the presence of current in the neutral wire can reach 36% of the total amount of additional losses. The review and analysis of the four most promising areas of modern research, innovative developments and experiments on the structural optimization of utility networks is given: a network with an increased voltage of 6(10; 35) kV and a reduced voltage of 0.4 kV with an isolated neutral; a network with an increased voltage of 6 (10; 35) kV and a reduced voltage of 0.4 kV with an isolated neutral; 0,95/0,4 /0,23 A network with two levels of high voltage of 1.14 (0.66) kV and a reduced line voltage of 0.23 kV with a grounded neutral of transformers; Fundamentally new methods of transmitting electricity over a single wire at alternating and direct current of increased voltage are described. The necessity of choosing the most rational integrated circuit solution for the structure and schemes of utility networks, which will reduce the loss of electricity in the networks, improve the quality of electricity and electrical safety, is justified.

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Ship Power System Analysis Based on Safety Aspects

Transport and Aerospace Engineering ◽

10.1515/tae-2017-0012 ◽

2017 ◽

Vol 4 (1) ◽

pp. 96-105

Author(s):

Margarita Urbaha ◽

Arnis Križus ◽

Deniss Kreisberg

Keyword(s):

Power Systems ◽

Fault Location ◽

System Analysis ◽

Electrical Power ◽

Diagnostic Methods ◽

Electrical Safety ◽

Fault Current ◽

Electrical Power Systems ◽

Current Compensation ◽

Isolated Neutral

Abstract This article analyses the reasons for the reduction of insulating resistance, processes influencing them and isolation diagnostic methods. It provides a short description of electrical safety situation on ships with isolated neutral electrical power systems. It also covers the methods of protecting personnel from electric shock or preventing ignition or arching damage at the fault location with the help of fault current compensation. Principal fault current compensation circuit diagrams are analysed by using the minimum value and time of transient fault current as criteria.

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