There are several types of induced voltages that can affect the potential of the cable core, screen and metal sheath. Conclusions and recommendations are given in Chapter 5. Some real examples on cables systems experiencing induced voltages, from different countries, are detailed in appendices. It is reminded that all these works must be carried out by qualified and certified personnel only.Ĭhapter 4 provides the calculation methodology of the three different types of induced voltages. In Chapter 3, a detailed summary of safe working procedures is given for several stages of work on cable systems: laying/pulling, cutting, jointing, terminating, testing, removal. Three different principles of safe work are given and detailed: Earthed working without currents (which is the recommended method), earthed work with currents and insulated working. This suggested risk analysis is explained in the Principles of Safe Work in Chapter 2. The basic principle underlined in the guide, is that before the start of any work on power cable systems, it is highly recommended that a risk analysis and the calculation of possible induced voltages be carried out. As this varies from country to country, and as there are several different standards discussing the topic, the task of the Working Group B1.44 has included an in-depth appraisal of these standards and guidelines and a thorough consideration to what should be recommended and included in appropriate International Standard.įigure 2 - Time/Current curves of effect of AC current through the human body Induced voltage mechanisms With the purpose of identifying what is a hazardous environment due to induced voltages or currents, there is a need for identifying the limit of touch voltages. ![]() In Chapter 1, the Technical Brochure starts by discussing and identifying the induced voltage phenomenon which can have several origins. This Technical Brochure references the risks associated with induced voltage on cable systems only it does not appraise or scrutinise other possible safety issues associated with other hazards on cable systems, such as mechanical stresses etc. Special safety precautions and appropriate equipment are indicated for different setups. Tunnels, open trench, ducts, HDD, ploughing and offshore installations are considered. In the Technical Brochure, different types of cable arrangements and installation are covered. These topics are not included the scope of work.įigure 1 - Example of single core HV/EHV cable Content The document does not provide detailed analysis of the effects of trapped charges and "return voltage" of HVDC cables (which are only mentioned briefly) or EMF. All possible kind of works such as Laying, Jointing, Terminating and work on Link Boxes.Protecting equipment (gloves, earthing systems.) necessary to achieve the work in safe conditions. ![]() Methods to calculate induced voltages and/or currents in various possible configurations (including EMF or Magnetic effect from cables or overhead lines installed in the vicinity).Permanent or fault conditions (Cable system stresses under grid fault).HV but also MV and even LV AC cables when they are part of the connection scheme,.The Technical Brochure is a comprehensive guide, in which all topics related to work under induced voltages or currents on land cable, and some of them regarding offshore cables, are addressed. When removing the cable for disposal at the end of its life.Īs hazardous conditions could occur, it is important to provide all parties that could be involved (utilities, manufacturers, installers, testing institutes…) with guidelines for safe work on cable systems, including a clear terminology.In the upgrading process of an existing circuit.During the repair of a cable after fault.When checking or maintaining link boxes.During the jointing operations in the installation process. ![]() HUANG (GB) Backgroundĭuring several phases of a cable system life (installation / maintenance / testing / upgrading/ removal), it can be necessary to work under voltages or currents induced by an energized system: For example:
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