In the last several years, Slovenian power distribution companies have been successfully carrying out preventive maintenance works within the framework of live working (LW) on both low voltage (LV) and medium voltage (MV). The utility company Elektro Gorenjska (EG) supported idea of implementation LW in Slovenia when activities started in 2006. At the end of 2010, the EG management decided to accelerate the process of introducing LW on low voltage (LV) and in 2013 also on medium voltage (MV) – cleaning of MV transformer station. In 2014, the utility company EG started the systematic planning of MV transformer station revisions with the LW method. This paper presents the multi-year experiences with carrying out LW on MV. It shows the effects on the indicators of power supply reliability in the period 2014–2021 and the advantages of carrying out maintenance works with the LW method on MV in the utility company EG and experiences with effects of LW on the improvement of indicators SAIDI (System Average Interruption Duration Index) and SAIFI (System Average Interruption Frequency Index).
Although statistics prove that live working methods are safer than de-energized activities, in some cases accidents may occur due to the neglect of safety rules. Generally, more than one safety factor shall apply individually to guarantee the expected level of safety; however, routine, hurry, or inattention might be very dangerous even during quite simple activities. The rubber glove method is widely used in the whole territory of Hungary and is a common practice in the area of surroundings of Budapest for almost ten years. In the fall of 2018, an unfortunate and serious accident occurred during dismounting a pole-mounted switch. Although the terrain and the geometry were not usual, this looked like a routine job for the practiced crew. While the job was performed, one of the workers suffered a major electric shock. Despite the immediate medical help, permanent damage has occurred. This paper introduces the circumstances of the accident and the measures which were performed by the responsible DSO in cooperation with the training center of BME.
The inspection of power lines using UAVs has become more and more common in the last few years. Albeit it is usually possible to fly the drones at a safe distance from the conductors, some specific measurements may require the UAV to get very close (tens of centimeters) to the power line. In this work, several tests that aim to assess the effects on UAVs of the electromagnetic field produced by high voltage live cables are presented. The issues detected during the experiments are solved using different technical measures that are tested in a real-world environment.
During live working operation, some operation shall be done on insulating strings or insulating columns. This article presents the principles applied by RTE to guarantee the withstand voltage of those insulating strings and columns according to the switching impulse voltage and to the insulators pollution level.
To ensure the availability of electrical power grid, some maintenance and installation works are sometimes carried out in the vicinity of live parts or near high voltage installations. In practice this means that work is carried out on double-and multi-circuit overhead lines and works are carried out on a circuit that is not under voltage (dead), while the other circuit is at the same time under voltage (live). In all such cases of work in the vicinity of live parts the workers must observe the appropriate safety distance, which is prescribed in regards to the voltage level and the third danger zone. Even when taking into account all safety factors, such works can cause increased risks to safety at work, for example risk of electric shock due to induced voltages, voltages of capacitive sets etc. To reduce these risks, special attention should be paid to ensure safety and health at work in the vicinity of live parts with appropriate regulations, reviews of dangerous occurrences, introduction of improvements to working tools and procedures, qualification of workers and consistent use of prescribed personal safety equipment. Based on domestic and worldwide practises, measurements and findings, we conclude that written safety instructions or a manual for safe work in the vicinity of live parts is necessary.
