The heat is on!

No rest in sight for TC 27 experts

By Morand Fachot

Countless products we use, consume or even eat can result from employing electroheating techniques. Electroheating is the high-power heating of various materials using electrical energy. Steel or aluminium ingots, ceramics and ready-made meals may be produced using this process. IEC TC (Technical Committee) 27: Industrial electroheating and electromagnetic processing, prepares International Standards for the many installations used in the sector.

Electric arc furnace for steel production (Photo: Deutsche Edelstahlwerke) Electric arc furnace for steel production (Photo: Deutsche Edelstahlwerke)

Not so new technology, relatively recent standardization

Electroheating was known well before its first industrial application, in which electric arc furnaces were introduced to the steel industry in the early 20th century. An electric arc is a plasma discharge that forms when a high electric current passes between two electrically conducting materials or "electrodes" through a normally nonconductive medium such as air. The temperature within the plasma can be over 6 000° C. In industry, this process is used for smelting and refining metals welding, plasma cutting and many other applications. 

A number of other electroheating technologies, such as infrared radiation, induction, radio frequency and microwave, have emerged since electric arc furnaces were first installed. Electroheating is applied in generic industrial operations such as fluid heating, calcination, drying, evaporation, sterilization, heat treatment, metal and non-metal heating, melting, smelting/agglomeration, curing and forming. 

Such operations are used for producing or processing many different materials, which range from metals to glass and from natural fibres to polymers – but are also used to prepare paper and foodstuffs (see article on industrial electroheating in this e-tech).

TC 27 was established in 1937 "to prepare international standards for characteristics, safety requirements and test methods for industrial electroheating installations". Its standardization work actually began in the 1960s. Its first standards, including IEC 60239, which dealt with dimensions of graphite electrodes for arc furnaces, were published in 1967. 

The scope of TC 27 covers all aspects of industrial electroheating, including electroheat-based surface treatment technologies, and their combinations.

Broad customer base, far-reaching remit

Electroheating equipment encompasses a wide variety of heating methods. Users of TC 27 standards are to be found in a range of heavy to light industrial sectors. They include the iron, steel and non-ferrous metal industries; automotive and machinery industries and cement, glass, ceramics and chemical industries as well as the food industry.

Emerging sectors such as nanotechnologies, biotechnologies, optoelectronics, the PV (photovoltaic) industry and the re-processing of waste and dangerous products require precise or unique heating methods. They also open up new perspectives for electroheating processes and present the need for new or updated standards. New heating processes using, for instance, laser or microwave heating, may sometimes provide the only possible solution to meet the requirements of a number of disparate industries.

Nevertheless, standardization in industrial electroheating is of great importance for manufacturers of equipment and installations. These are mainly small and medium-sized enterprises and their products are often individually-designed and custom-engineered according to the specific needs of end-users. Establishing common international standards for equipment with different characteristics and safety requirements may be difficult, but fully supports the trends towards global harmonization and the reduction of trade barriers.

Specific issues

Electroheating installations that use electromagnetic processing may prove to be sources of EMI (electromagnetic interference), leading the TC to address specific aspects of EMC(electromagnetic compatibility) and EMF (electromagnetic fields).

As electroheating technologies extend to more sectors and represent a large percentage of industrial electricity consumption – between 20% and 40% in the European Union, according to TC 27 data – EEE (electrical energy efficiency) becomes a pressing issue. This is despite the fact that electroheating is usually more energy efficient than processes burning fossil fuels, as it can be switched on and off immediately. It also offers more uniform heating temperatures.

To tackle the energy efficiency issue, TC 27 set up WG (Working Group) 29: Energy efficiency in electroheating installations, to "develop guidelines for determination of criteria (…) for allowing fair comparisons and evaluations of the performance and efficiency within particular sub-categories of electroheating equipment / installations".

TC 27 also established WG 30: Industrial infra-red electroheating installations, "to develop standards concerning safety and test methods for industrial infra-red electroheating installations".

Multiple objectives

Noting an "increasing demand for energy savings, product quality and environmental protection" and that "application areas of electroheating methods are not only expanding but also becoming a must for many industrial sectors", TC 27 lists as its objectives and priorities for the next 3-5 years:

  • the revision of the 12 publications in the IEC 60519 series of standard that deal with the safety of industrial electroheating installations
  • the preparation of additional parts covering particular industrial electroheating installations, such as those with infrared emitters or laser heating equipment
  • the revision of the large series of test standards, which should be updated in view of technological developments and market needs In addition to its revision work, TC 27 also intends to start work on new standards, while amending the existing publications, to address:
  • EEE issues (guidelines for the classification of equipment/installation to determine the performance/efficiency of a given system and a comparison with other systems of that class)
  • EMC and EMF issues
  • safety and test methods for different electroheating installations, in particular new ones or those not covered by existing standards
  • safety and reliability aspects of combining heavy current electroheating equipment with sophisticated digital control methods

To take into account the predicted long-term evolution of electroheating technologies, TC 27 announces its intention to undertake new projects aiming at developing safety and test standards for:

  • infrared heating technologies
  • plasma arc furnace installations
  • new casting systems
  • electromagnetic processing of materials.

Widespread cooperation

To achieve this extensive range of objectives, IEC TC 27 recognizes the need to broaden its resources through the medium of specialists who prepare diverse electroheating standards. To do so it intends to collaborate with a number of international and regional industrial societies that deal with thermoprocessing equipment. They include the UIE (International Union for Electricity Applications), CEN (European Committee for Standardization) TC 186: Industrial thermoprocessing – safety, and the relevant ISO (International Organization for Standardization) TCs.

The development of current electroheating processes coupled with the emergence of new technologies, considered in conjunction with IEC TC 27's objectives, point to the likelihood of an extremely busy agenda for this sector in coming years.

Electric arc furnace for steel production (Photo: Deutsche Edelstahlwerke) Electric arc furnace for steel production (Photo: Deutsche Edelstahlwerke)
Vacuum drying oven used in pharmaceutical and chemical industry (Photo: IBK GmbH) Vacuum drying oven used in pharmaceutical and chemical industry (Photo: IBK GmbH)
Heaters in continuous coil coating dryer (Photo: Casso-Solar Technologies) Indexing chain conveyor oven (Photo: Grieve Corporation)