Abstract
Changing the connection type of a medium voltage (MV) cable screen is linked to a decrease in power loss, although it may also lead to the generation of overvoltage in a metallic cable screen, which is hazardous for proper cable line work. In this paper, results of simulation and field researches are presented, showing the range of voltages that occurs in cable screens during single-phase ground fault. There are considered to be three scenarios according to the applied type of cable screen connection. Conducted researches allow the comparison of chosen methods of simulation with an actual outcome. Results obtained during simulation and field studies lead to the conclusion that the range of overvoltage occurred in a cable screen could in fact be dangerous for the cable line’s sheath insulation without proper overvoltage protection.
Highlights
The reduction of power transmission losses resulting from the flow of electricity through conductive elements in the transmission and distribution system is a problem of significant importance
According to the literature [3], eddy currents constitute a small percentage of the total losses, and do not depend on the arrangement of the cable screen connection—the main purpose of limiting losses methods is associated with minimizing the flow of induced current in the cable screen
These simulations were aimed at verifying the correctness of the thesis concerning the medium voltage ground fault overvoltage which is dangerous for the operation of the network in a system with cable lines
Summary
The reduction of power transmission losses resulting from the flow of electricity through conductive elements in the transmission and distribution system is a problem of significant importance. Cable lines is a particular case, in which apart from losses in the conductor, additional losses related to the current flowing through metallic cable screens or cable sheaths are observed [1,2]. Losses associated with the current flow and occurrence of eddy currents can be distinguished. According to the literature [3], eddy currents constitute a small percentage of the total losses, and do not depend on the arrangement of the cable screen connection—the main purpose of limiting losses methods is associated with minimizing the flow of induced current in the cable screen. In order to increase the efficiency of electricity transmission via cable lines, these losses can be reduced by using methods based on changing the configuration of the cable connection method or grounding configuration of the cable screens. Among the methods using grounding configuration changes, the most commonly described by literature are single point bonding [4,5], cross-bonding [4,6]
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