The role of standardization in electromagnetic compatibility

Bertrand Daout, Technical Director of Swiss-based Montena EMC, talks to e-tech's Flip Martin-King.

This article originally appeared in the July 2007 issue of IEC e-tech.

Montena EMC is a specialist in electromagnetic fields and the disturbances they produce. They both create systems that test and measure EMC (electromagnetic compatibility) and carry out testing and measurements themselves. Once they were asked by the resident of a house to investigate the case of a "singing building". They found that the music came from drainpipes which were acting like loudspeakers and broadcasting the sound waves picked up from local transmitters. The sound had been induced by the transmitted waves being demodulated on diodes that had formed when the drainpipes had oxidized.

As a solution, they connected the drainpipes together with a wire strap which not only shortened the "demodulator" and prevented the drainpipes from broadcasting their tunes, but, at the same time, they also added an efficient lightning conductor to the house – another area where Montena is particularly active. There are many cases of EMC disturbance that get reported in a domestic setting including singing saucepans and telephones. Montena's speciality is to go out, track these down and, based on their findings, find a suitable solution to the problem.

e-tech: Why is it important to measure and control energy?
Bertrand Daout: Our lives today are driven and controlled by electronic apparati such as the Internet and telephones that are used for our daily communication and we rely heavily on being able to depend on these automated services. Consequently, we need to be able to measure and, more importantly, control interference such as voltage spikes, or energy spikes. Then, using surge protection equipment, one can regulate the voltage that is supplied to an electric device and either block or short it so that the equipment does not get damaged.

e-tech: What does compatibility mean in terms of EMC?
Bertrand Daout: Before, when EMC was not of particular importance to equipment manufacturers, the situation was fairly chaotic. However, with the advent of digital technology, it became increasingly necessary for regulatory organizations to create legislation on EMC because without it, there was little possibility of knowing the full extent of equipment in comparative terms, what measurements had been used to define and test it and whether it would be compatible in a particular application.

One area that is now heavily affected by EMC is that of data networks. Imagine that you are working on a wireless network. You want to be sure that no one is able to take on your identity and use your computer without your knowing it. You need to know that your information remains personal and confidential and that your neighbour is not reading your email.

In the past, everyone was a witness to the effect of an electrical appliance interfering with the image on a television screen. Picking up a signal from a computer screen works in very much the same manner. It all has to do with electromagnetic interference. This is one area where future standardization could play a vital role in setting the appropriate levels.

e-tech: What standards are used to ensure that measurements are precise?
Bertrand Daout: There are literally hundreds of standards on which we base our tests and equipment manufacturing. Often, only a few pages of the thousands published are actually relevant to each precise measurement. However, it's absolutely essential to understand how and under what conditions particular measurements need to be carried out.

For instance, simply displacing a cable or an antenna a short distance away can make an enormous difference to the effect of EMC. In this case, IEC standards, such as those issued by Technical Committee 77, Electromagnetic compatibility and the three subcommittees, SC 77A, Low frequency phenomena, SC 77B, High frequency phenomena, SC 77C, High power transient phenomena are extremely useful in defining test conditions, whether for us, our clients or the competition. We all know that we are talking the same language and using the same criteria.

e-tech: Why do your customers require standards?
Bertrand Daout: Before standards existed there was a certain euphoria perhaps in knowing that there were no limits, but equally, there was stress. It's a little like driving a fast car along a wide road without a speed limit. While there is exhilaration in the unrestricted pace, at the same time, there's an inherent danger that, after a while, permeates the atmosphere and detracts from the original freedom. Standards provide a basis and a framework in which to work.

In the past , customers would only have come to us once there’d been a crisis of some sort. Now, before a product is brought to market, its manufacturer will already ask us to provide them with the relevant specifications that will allow them to adhere to legislation at the same time satisfy market requirements in terms of expected safety. It’s something that perhaps they resist in a certain manner but, like the car driver, they know is good for their reputation as manufacturers and important for the safety of their own customers.

e-tech: And your activities in lightning protection?
Bertrand Daout: Montena is particularly specialized in ensuring that people who are working outdoors with portable radio communication devices are fully protected should they be hit by lightning. Imagine someone in the middle of a forest clearing, miles away from base camp, during a raging storm. It's difficult to actually measure how much energy a person can actually absorb without it being fatal, so Montena developed testing methods using different types of soil or ground in laboratory conditions in order to come up with measurements that could then be used as models for creating solutions.

On the basis of these simulated conditions, we were able to validate our theories using a lightning generator to send mammoth surges of thousands of volts that simulated lightning bolts onto a 500 Ohm resistance which they set as their human model. Obviously, we weren't able to reproduce the true wave lengths of lightning and therefore had to extrapolate the results of our measurements by adding various factors into the calculations. But this served as a very good basis and gave us sufficient knowledge to provide an adequate solution for each particular outdoors situation.

Is there any specialized area of EMC where standardization is still lacking?
Bertrand Daout: EMP, which stands for electromagnetic pulse, is one of our more niche areas of activity. From it one also gets the terms NEMP (nuclear electromagnetic pulse), NNEMP (non-nuclear electromagnetic pulse) or HEMP (high-power or altitude EMP). There are few up-to-date standards, particularly those written for civilian purposes, covering the subject of EMP.

An EMP relates to the electromagnetic radiation that follows an explosion, or a highly intensive, short broadband burst of electromagnetic energy. Whatever the cause of the outburst, be it a nuclear explosion or the impact caused by an asteroid, the powerful field that results from the electromagnetic energy it generates, although not audible to man, is potentially tremendously damaging for electronic devices.

It therefore represents a distinct financial threat, both in terms of having to replace costly equipment and in the time spent re-installing it. The US Army published a standardization pamphlet on EMP in 1990. China also has an aging translated version heavily inspired by a previous US publication, so yes, there is a need for new standards that have been developed for modern day purposes.

In the case where there was a risk of EMP, it would be necessary to test equipment to ensure it was capable of withstanding the impulsion to which it might be submitted. Our testing laboratory is huge. In fact it's large enough to contain a helicopter and, depending on need, we carry out all sorts of specialized tests, quite often developing our own installations for a particular laboratory or manufacturer of specialized equipment.

Etech: How much of your business is generated or influenced by the existence of standards?
Bertrand Daout: Since the European EMC Directive was issued on 1 January 1996 and ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories came along subsequently, I would estimate that our business has tripled. Industry became increasingly conscious of the need to test and measure and in the immediate period after it was issued we doubled our work.

Today, we have a highly specialized staff of 30 people and three different sites. Roughly one fifth of our activity concerns domestic applications. The major part is taken up by industrial and scientific needs. This is largely due to there being little actual domestic type manufacturing in Switzerland. Roughly half of our time is spent on measuring, the other on manufacturing testing equipment where, for NEMP, we are world leaders. As far as measuring is concerned, our business is mostly local. Clients will nearly always look for a service provider in the immediate vicinity since the time scale involved is generally short and varies from a few hours to a couple of days.

Source: International Electrotechnical Commission (IEC).