For those who are not familiar with the issues related to Electro-Magnetic Compatibility I will begin by describing the basics. First there is the need to protect radio services from the background noise that is generated by modern electronics, and then there is the performance issue if the product cannot operate correctly in the electro-magnetic environment that exists in the location where it is installed.

What causes EMC problems

Any product which uses a clock to operate (using synchronous logic, a micro-processor, or a larger computer) generates harmonics of those frequencies. The number of harmonics and their intensity are a function of the electronic design and the rise/fall times of the edges of the signals. Those who have heard of the Fourier series will better understand what is happening, but in plain terms the faster the edges and the greater the energy used in generating those edges, the higher the harmonic frequency and higher of each of those harmonics. If there is a conductor or PCB track carrying that noise that is resonant then there will be a noticeable radiated signal. Good design practices can significantly reduce the levels and number of frequencies emitted by the product.

Controlling EMC

In order to protect the radio services and broadcast television signals many countries have adopted regulations. There are a large number of essential radio services which include all of the emergency services, aircraft and marine navigation and traffic control to name a few.

Requirements

There is an interesting article on ‘EMC and Common Standards’ that has recently been distributed by Amplifier Research Inc. and provides a basic overview of the standards that are used in the English speaking world and can be found at  the link here. .

Many countries around the world have similar requirements to Europe, Canada and the US. I will deal with the others in future editions as well as the requirements for equipment that emits intentional radio signals such as WI-FI, Bluetooth, and many licensed services.

Planning for compliance

The most dangerous approaches are to assume that your product will pass with the production sample, and the test time is flexible. In most designs it is preferable to plan ahead, incorporate EMC suppression in to the product design at the beginning as it can be easily removed later if you do not need it, do a preliminary test of the first prototype (this can be emissions as a minimum), and do not assume that delays in the schedule can be covered by reducing the final test time.

Here are a few books that may help by suggesting ways to reduce the potential for EMC issues:

1) PCB Design for Real-World  EMI Control by Bruce Archambeault, ISBN 1-4020-7130-2. This one looks at common EMC solutions for PCB’s and based on modelling and practical experimentation suggests which will work, and not work in various situations.

2) Electromagnetic Compatibility Engineering by Henry Ott, ISBN 978-0-470-18930-6. This book provides a grounding in the background theory and practice in EMC.

3) EMI Troubleshooting Cookbook for Product Designers: Concepts, Techniques, and Solutions by Patrick Andre and Kenneth Wyatt, ISBN 978-16135030196. This book covers design, diagnostics, and troubleshooting tools.

Legal Requirements and Penalties for Non-Compliance

The requirements vary from country to country, as do the enforcement and penalties. A growing number of countries have tied their requirements to those in the European Union.

In most countries the proper documentation is required at customs before the product is cleared. If it is held because the documents are not sufficient then a daily storage charge is applied.

Canada, the US, and Mexico have similar requirements, and given the Free Trade Agreement the minimum requirement are the ones set by the FCC. Canada and Mexico also have their own standards that are based on the International Emissions standards. Other countries such as Turkey, Israel, South Africa, Australia, etc.  use the European Limits and add their own documentation requirements.

The penalties vary widely as well. In North America non-compliance will result in an order to shut down the offending product, and cash penalties will apply daily for each unit that remains in operation. If the manufacturer takes an active role in correcting the problem the penalties are minimized, but if there is no active response then an order to recall all units can be issued.

In Europe a failing product will require a response form the manufacturer, and the importer. If the Declaration of Conformity that was used to allow the product into Europe proves to be false the signatories will be charged with Fraud, and can expect to be arrested at Immigration when entering the EU. In addition the country finding the non-compliance is required to notify the Commission who then notifies the other members. The other penalties vary from country to country, and one of the most severe is Germany where if there is no immediate corrective action they will order all units to be recalled, and replaced with an equivalent compliant product.

In Japan VCCI ( the Voluntary Control  Council for Interference) is an industry based organization, and failure to satisfy their requirements can result in the details of the non-compliance being published in the popular press and the requirement to remove the compliance label. Given the general  Japanese attitude towards negative press and the public good, sales to the public will diminish.

USA

In the US the agency is the FCC (Federal Communications Commission) whose mark is displayed on all products which contain a clock. These regulations contain many parts and deal with any product that emits radio frequencies from home appliances, radio transmitters, Medical Devices, X-Ray units, to welding, and RF material treatment products.

The FCC rules define the limits for Class B equipment that is used in a residential setting (where a radio or television receiver can be nearby), or sold at retail to the general public. Radio Transmitters are the exception and they have requirements appropriate to their operating band, and output power.

There are no regulations in the US for the immunity performance except in cases where the inability to operate correctly presents a safety hazard such as a car, an airplane, or a medical device. Industrial Equipment must comply with the Class A limits which are higher since these products are generally used at a distance from a residential area, and are installed by qualified personnel. The products must bear the applicable label, and if manufactured outside of the US be accompanied by a declaration that they comply with the rules.

Radio Transmitters must be certified as compliant by a Competent Authority that is accepted by the FCC, and be labelled accordingly.

Copies of the rules can be obtained from their website at https://www.fcc.gov/engineering-technology

Canada

In Canada the agency is part of the Innovation, Science, and Economic Development Department (ISED) who have prepared a series of Interference Causing Equipment Standards (ICES), and Radio Equipment Standards (RSS).

Canada has adopted similar requirements to those in the US and accepts either the International requirements or the respective FCC ones in order to facilitate free trade. The Canadian regulations specify that a Canadian Compliance Statement be used.

The Canadian Standards are available from https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf01375.html.

European Union

The European Community has adopted as series of standards (EN’s or European Norms) and prepared Directives which regulate their application. The CE marking rules outline the requirements, for using the mark and the responsibilities of the manufacturer, with each member country responsible for implementing the requirements in their national legislation, including the penalties for non-compliance.

The goods entering Europe require a Declaration of Conformity to all of the directives which apply to the item (i.e. EMC, Electrical Safety, Hazardous Material, and Medical devices to name a few). The countries also can add an additional inspection when the goods cross the internal border. It must be noted that Europe has adopted the requirement that the products also meet the Immunity limits based on the location of their operation because they feel that owners should be entitled to a reasonable level of performance in a typical environment.

A number of other countries accept the CE marking although they are not part of the EU. These include Switzerland, and Turkey. Australia will accept the mark but they also require an Australian compliance file be retained by the importer, and have their own compliance mark.

Lists of the accepted European Standards for the various categories are available at https://ec.europa.eu/growth/single-market/european-standards/harmonised-standards_en.