The problem of efficient and safe mining has recently become more relevant due to the intensification of production processes, for example, during the operation of electrical installations at mining enterprises, the insulation of electrical networks and electrical equipment undergoes a change in the electrical insulating properties of materials, which reduces the electrical safety. The network insulation admittance determines the safety of electrical receivers and operational personnel in mining facilities, since the current of a single-phase earth fault is directly proportional to the value of the network insulation admittance, and by controlling its active and reactive components, this will allow for a violation of the integrity of the insulation, thereby taking preventive measures. The article depicts the analysis of the reliability of the devised method by estimating the error of insulation parameters in ungrounded AC systems which is done by indirect measurements. Graph-analytical studies of relative root-mean-square error reveal that the accuracy of the calculation in the devised method can be effectually managed by selecting the susceptance of the additional capacitor and accuracy class of measuring units.
For the safety of humans and animals in the vicinity of single‐phase earth faults in ungrounded AC systems, the development of methods for monitoring the condition of insulation and protection against electric shocks is an important issue. This paper presents a method for determining insulation parameters in ungrounded AC systems, which provides: (1) Satisfactory accuracy; (2) easy measurements of the voltage modules magnitude; (3) safety when working in electrical installations. The proposed method is based on measuring the zero‐sequence voltage module and phase‐to‐earth voltage module, as well as the angle of phase‐to‐earth voltage vector and zero‐sequence voltage vector before and after connection of additional conductivity between a phase and the earth. In addition, the obtained insulation parameters enable the zero‐sequence current to be decomposed into an active and reactive component, thus ensuring accurate compensation of capacitive currents. By monitoring the state of the active conductivity value, the value of the single‐phase earth‐fault current can be determined at an early stage and the relay protection can thus be correctly set. Consequently, by knowing the insulation condition parameters, the single‐phase earth‐fault currents can be monitored and reduced more effectively, and thus the step voltage, which determines the degree of safety.
"One of the factors that determine the safety of electrical installations in ungrounded AC systems is the insulation resistance to earth. Early recognition and fault clearance, accompanied by a change in the active and reactive components of the insulation conductivity in ungrounded AC systems, will ensure work safety in electrical installations. Due to the fact the scale of cases of electrical injuries continues to remain significant, despite the tightening of the requirements of regulatory and technical documentation and the creation of newer effective methods and protection equipment against electric shock, therefore, increasing the level of electrical safety in the operation of mining machines and complexes is an urgent task. The article depicts the results of the approbation of the developed method for determining network insulation parameters on an operating excavator. The developed method is based on measuring phase voltages and angles of their vectors before and after connecting an additional capacitance to the phase of the electrical network and to the earth. According to the developed method, numerical data of the insulation condition in an electrical network with a voltage up to 1000 V and the single-phase earth fault current were calculated. During the approbation of the developed method, the lack of the existing protective residual current device was identified. Keywords: network insulation, admittance, susceptance, neutral shift, zero-sequence voltage. "
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