What is EMC for Functional Safety?

All electrical and electronic technologies emit electromagnetic interference (EMI) that can interfere with the correct operation of radiocommunications and other electronics. Modern electronic technologies are more likely to emit EMI at higher levels and higher frequencies than older ones.

All electronics (and software) can suffer degraded functionality (including complete failure) when exposed to interference. Modern electronic devices are usually more susceptible than older ones.

Modern electronic technologies are being increasingly used everywhere (e.g. computers, cellphones, power conversion) and so the EM environment is becoming more polluted day by day. At the same time – modern electronic devices are increasingly being used in safety-related and safety-critical applications (such as ESP and ABS in automobiles).

As a direct result of these trends, it is increasingly likely that errors and misoperation of electronics and software due to inadequate EMC will result in increased safety risks.

Many people think that all that is necessary for EMC in Europe is to meet the EMC Directive, but in fact the EMC Directive and its harmonised EMC standards do not cover Functional Safety requirements (this has been officially stated, references available on request).

In the European Union (EU) – EMC for Functional Safety is covered by EU Safety Directives, even if they don’t mention it. These include:

  • Machinery, Low Voltage Equipment, Explosive Atmospheres, Pressure Systems, and Personal Protective Equipment Directives
  • The Automotive EMC Directives
  • The three Medical Devices Directives
  • Product Liability and General Product Safety Directives
  • Provision and Use of Work Equipment, and other Health and Safety at Work Directives

Unfortunately, so far none of these safety Directives or their listed harmonised safety standards correctly deals with EMC for Functional Safety.

In the UK, larger projects may find ‘EMC for Functional Safety’ requirements are covered by one of the following…

  • The Offshore Installations (Safety Case) Regulations as amended by the Offshore
  • Installations and Wells (Design and Construction, etc.) Regulations, 1996
  • The Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations, 1995
  • The Control of Major Accident Hazard Regulations, 1999 (COMAH)

Since many manufacturers and project engineers only seek to do the barest minimum that the laws appear to require – to keep costs low – the fact that neither the EMC or Safety Directives nor their standards deals with ‘EMC for Functional Safety’ means it is often ignored completely.

Consequently, users and third parties may be exposed to safety risks, and manufacturers and construction companies may be exposed to high levels of risk and liability without realising it.

EMC should be considered during hazard analyses and risk assessments, which should consider…

a. What interference, however infrequent, might the apparatus be exposed to?
b. What are the reasonably foreseeable effects of such interference on the apparatus?
c. How might the emissions from the apparatus affect other apparatus?
d. What could be the reasonably foreseeable safety implications of the above?
(E.g. what is the severity of the hazard; the scale of the risk; the safety integrity level required according to IEC 61508)?
e. What actions are necessary, in both design and verification, to achieve the desired level of safety?
f. What documentation is required to show that all of the above have been dealt with well enough?

The amount and quality of the activities and documentation required to show due diligence varies greatly from one organisation to another. In general, where hazards and risks are higher (i.e. a higher safety integrity level applies), a higher level of activity and documentation is required.

Our qualifications and some useful resources

Click here for a general introduction to EMC for functional safety (96kB, Word format).

Keith Armstrong of Cherry Clough Consultants is the initiator and chair of the IET’s Working Group on EMC and Functional Safety (see their guide) and is the UK’s appointed expert on the IEC 61000-1-2 (EMC and Functional Safety) and IEC 60601-1-2 (medical EMC) standards committees.

Keith is a prime mover in this field, and has been writing and presenting on it all over the world since 2000, including major international symposia such as the IEEE International EMC Symposia and the IEEE International Product Safety Engineering Society Symposium. A comprehensive list of resources and references on EMC for Functional Safety written by Keith is provided by the IET at: http://www.iee.org/OnComms/PN/emc/EMCandFunctionalSafety.cfm

How we can help

Because of our long association with EMC for Functional Safety, and our qualifications above, we are very well placed to help you control this issue in the most cost-effective way, using modern good safety engineering practices to reduce safety risks and exposure to liability claims.

We can provide training, and assistance with design and procedures for ‘EMC for Functional Safety’, for…

  • Components and modules
  • Products, appliances, instruments, etc.,
  • Vehicles (land, rail, sea, air, space, etc.)
  • Custom designed equipment, machinery, plant
  • Systems
  • Installations (buildings, campuses, factories, theatres, hospitals: any structure or site)

…of any type, any size, for any application (including safety-critical, nuclear and military).

We speak plain English engineering language.

Our aim has always been to transfer our knowledge and experience to your own personnel, to get them up their learning curve quickly with the lowest costs, so they don’t repeat the costly mistakes that so many people have already made.

We recognise that design consultants like ourselves are not inexpensive to employ, so we aim to minimise what you spend on us. This means we are always trying to make ourselves redundant, so you need us less and less as your personnel’s expertise increases.

It costs much less overall to employ our training or expertise early in a project to help prevent problems from arising at all, or to fix any problems as soon as they appear.

How we work with customers
Download Non-disclosure agreement (Word document 36K)