Understanding EMC testing complexity

| Environmental Testing

Test houses have the capability to perform EMC emission and immunity testing in appropriate chambers

Pete Dorey, Principal Consultant at TÜV SÜD explains some of the complexities of EMC testing

Electromagnetic compatibility (EMC) testing measures the ability of equipment or systems to function satisfactorily in their electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment. EMC compliance is a mandatory requirement in most markets, including Europe, the US, China, Korea, Australia and New Zealand.

In the EU, the majority of electrical products must comply with the EMC Directive 2014/30/EU, as well as other relevant Directives, before they can carry the CE marking. Following Brexit, in the UK this directive has been replaced by the Electromagnetic Compatibility Regulations 2016, and products must comply with this before they can carry the UKCA mark.

There is a two-year transition period where products can continue to carry only the CE marking in the UK. Currently, the requirements of the UK EMC Regulations and applicable EMC standards remain the same as those of the EU’s EMC Directive, but may diverge in the future.

EMC is an issue that many designers and manufacturers find complex and confusing, but that does not mean that they can ignore their legal obligation to ensure their products meet requirements. Neither should those manufacturers integrating components into their final product plead ignorance, making the assumption that their supplier is doing the right thing.

The standards set strict limits for emissions and immunity. Emission limits control the amount of electrical interference that a device produces that might interfere with radio and television reception, mobile phones, Bluetooth, WiFi and the host of other wireless technologies that we use today.

Immunity limits require the product to operate in its intended electromagnetic environment without upset or degradation to its intended functions. Equipment must therefore be designed and manufactured so that the electromagnetic disturbance it creates is not excessive, and so that it has a reasonable level of immunity to electromagnetic disturbances. While a single item of equipment might meet these limits, there is no guarantee if you combine multiple items or additional components, that for example, the overall emission levels will still be satisfactory therefore the final integrated product must be assessed against EMC standards.

Not only does EMC testing ensure that products meet regulatory requirements, it reduces the risk of costly non-compliance, which could require product recalls, or cause significant time-to-market delays for new products. Third-party EMC tests and conformity assessments help to ensure that a product maintains its desirable features when exposed to adverse conditions (immunity test) and does not cause undue interference (emission test).

This can help to strengthen a brand’s competitive position in the market due to improved product performance and reliability by reducing the chances of failures in use. The two key drivers of brand loyalty and product quality can therefore both be beneficially influenced by such tests, helping to ensure that the product maintains its desirable features when exposed to adverse conditions will support brand loyalty.

For immunity testing there are three performance criteria A, B and C that are specified in the EMC standards and each immunity test has one criteria specified. Criteria A requires the product to continue operating as normal at all times and applies to tests for continuous EMC phenomena (like immunity to adjacent mobile phones). Criteria B allows some degradation during the test condition and applies to tests for transient immunity (infrequent events, such as electrostatic discharge due to someone touching the equipment). Criteria C allows temporary loss of function and applies to severe transient immunity which is very infrequent, such as a power surge or supply voltage interruptions. Permanent loss of function will be a failure.

Manufacturers can minimise the costs and time associated with EMC testing by proper preparation for test:. A test laboratory sees many thousands of products each year – they will not be familiar with your product, so you must brief them fully. A successful testing programme is the result of you disclosing as much information to your chosen EMC test laboratory about the equipment under test (EUT) as early as possible in the project cycle., with a special focus on:

* Block diagram of the test configuration and any support equipment to exercise or monitor the EUT
* Mode of operation for emission to maximise potential interference and highest internal operating frequencies
* Mode of operation for immunity to exercise critical functions and method of monitoring to determine if function is upset or degraded
* Power supply requirements
* List of signal interface ports, type and cable lengths
* Grounding arrangement

This information will help the laboratory to develop a realistic test plan, enabling you to more accurately anticipate time and cost for test.

Consideration of EMC at earliest stage in the design process will help manufacturers to minimise test failures and the time and cost for reworking their design and retesting. A product lifecycle review will also highlight any design measures required to maintain a product’s compliance. This will help manufacturers increase the return-on-investment that they get from their EMC testing, help to ensure that the EMC integrity of products lasts a lifetime and enhance a brand’s reputation for product reliability.

Electronics Industry Compliance Academy Opens

TÜV SÜD has launched an academy to help the UK’s electronics industry to cost effectively upskill their employees to optimise business performance, improve product compliance efficiency and minimise time to market.

Part of a global training programme, TÜV SÜD Academy will offer more than 60 knowledge transfer courses to individuals and entire organisations. A mix of instructor-led workshops and e-learning courses will aim to maximise flexibility for how and where businesses want their people to learn.

Electronics and electrical training courses will cover seven core areas:

* CE & UKCA certification
* Cybersecurity
* Electrical safety
* Healthcare & medical
* Machinery safety
* Quality management

According to David Goodfellow, Head of Business Assurance at TÜV SÜD, the experts at TÜV SÜD have a wealth of experience and UK organisations can now access that knowledge through the TÜV SÜD Academy to help them increase business efficiency at multiple levels.

“We are dedicated to helping people and organisations drive business performance to levels of excellence, without compromising on costs efficiency or time to market. The TÜV SÜD Academy enables us to extend that mission through direct knowledge transfer into UK industry,” says Goodfellow

Jonathan Newell
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