Live working is essential as it prevents unnecessary outages, which are disruptive to electricity users and costly both to the utilities and the users in terms of loss of revenue, interruption of manufacture, administration resources and penalties.
Live working also allows power network operators to achieve efficiencies through cost-effective preventive maintenance, improved reliability and availability without any requirement for an outage.
Live electrical work is extremely hazardous because wires can be active without showing any visible indication of being charged, and because electric shock can result from low currents. IEC TC (Technical Committee) 78: live working, develops international standards for tools, equipment and devices intended for work on, and in the vicinity of, live parts of electrical installations and systems. This includes their performance requirements, care and maintenance.
Stability and changes
Outgoing TC 78 Secretary Claire Vincent, recipient of the 2012 IEC Thomas A. Edison Award, shared her views on the TC's work as she was getting ready to step down.
Vincent says she moved into the live working domain quite naturally after specializing in electrical insulation and working in the high voltage domain with Hydro-Québec. She later got involved in standardization before being elected TC 78 secretary.
"The interest of my work is that I learned something new every day", she says.
Reflecting on the protective equipment used in live working Vincent says some of it hadn’t changed that much in decades. "What has changed are the materials used, polypropylene replacing rubber in gloves, for instance".
Other protective kit has evolved quite significantly over the past 5-10 years, in particular equipment meant to protect from the effects of electric arcing, such as masks, helmets, etc. These are given special attention nowadays and particular emphasis is being placed on research into electric arcs. This in turn may lead to new work methods and the development of new materials (high temperature conductors, different composite materials, etc.).
The installation of optic fibre cables along power lines, which are used by utilities to control the network and to set up smart grids, is one of the new technologies that have an impact on live working. It requires more installations on power lines as the new cables are installed on, or in parallel with, power cables. A new generation of power cables is being manufactured with embedded optic fibre cables.
New technologies may change the way live working is carried out, on power lines in particular.
One option that is being used increasingly is the deployment of robots, so-called LineScouts, which are mounted on overhead lines, travel along them and check their condition remotely. The installation of such robots, which must be hauled up from the ground, requires certain precautions to protect their electronic systems.
Another spectacular new form of live working involves the use of a helicopter that carries a technician. The pilot hovers carefully near overhead lines whilst the technician works on them. To do so he must first connect to the lines with a special rod to equalize the electrical potential between helicopter and line, so as to drive the current around the helicopter and avoid shock. This method of live working is particularly perilous as the pilot must ensure that helicopter, live lines and other obstructions don’t come into direct contact with each other.
If many working practices and equipment are well established, some new technologies pose fresh challenges for live working. The relatively recent installation of microwave and mobile communication transmission equipment on power line pylons poses particular challenges as the effect of radiations emitted by these systems on technicians working on overhead lines is not yet known. TC 78 liaises with TC 106: Methods for the assessment of electric, magnetic and electromagnetic fields associated with human exposure, to evaluate any possible impact on workers.
Fond memory of TC work and contacts
As she steps down from her position Vincent recalls fondly her years as TC 78 secretary. Although experts from the TC and their Central Office colleagues may not meet very often, they maintain frequent contact, sometimes on a daily basis. "They were more than colleagues, they became friends", she says. Vincent expressed her satisfaction to see young experts keen to join standardization work, thus ensuring its future.
Vincent also stresses the constant liaison work with many other IEC TCs that are either customer or supplier to TC 78.
Vincent will have warm memories of her time as secretary of TC 78 as she reflects on the significance and wide scope of the TC's work, as well as the closeness of contacts between its experts.
TC 78 publications are widely used at regional and national levels, and are often adopted as national standards. They are increasingly referenced in legislation, which can have business impacts. They are also used as the basis for contracts
New technologies and work methods will ensure its activities will evolve constantly to remain relevant to the industry.