Behind closed doors

| Environmental Testing

EMC testing chamber at Dyson

Dyson performs all its EMC testing at its own closely guarded facility in southern England. Fabio Scalon provided Jonathan Newell with a glimpse behind these closed doors to find out why.

With the consumer technology industry being so highly competitive, the secrecy surrounding the research, development and subsequent know-how has been crucial in making Dyson a household name.  But how does the company manage this?

To find out, we spoke to Principal Engineer Fabio Scalon about the increasing industry demands for accurate assessment of products and growing product complexity.

Since its foundation a little over 20 years ago, Dyson has been well known for being at the forefront of technology and development. Due to the fiercely competitive nature of the company’s markets, its research and development testing facility in Wiltshire is a well-kept secret. And Dyson wants to keep it that way, to ensure that it can protect its developments and patents.

However, alongside that, the company also has to meet the challenge of increased industry standards for testing compliance. With increasing industry demands for accurate assessment of products, the company routinely carries out EMC assessments of its products during development, such as its domestic vacuum cleaners and commercial hand dryers.

Intellectual property is key to the company’s ability to differentiate itself in the marketplace, so it is essential that it is adequately protected. One way that Scalon believes Dyson can achieve this is to perform all of its testing at a dedicated in-house facility; this includes an on-site EMC chamber in which all of the company’s products are tested. “This is an essential element in maintaining confidentiality and keeping product developments on-site, rather than shipping them to outside test facilities,” he says. “To do this, Dyson tests to full industry compliance on-site.”

Having originally commissioned a 3m semi-anechoic EMC Chamber (SAC) back in 2006, Dyson has since had to upgrade it in order that it could meet the changing and increasingly stringent industry test standards and frequency ranges that are demanded.

The search for a supplier of the chamber upgrade extensively examined the capabilities of all known major suppliers of chambers. This kind of stringent process is something which Scalon advises others to follow, looking at all areas of the supplier including price, performance and references.  “Most importantly, how can they support you after installation and commissioning and what level of after-sales service do they offer?”

Upgrade evaluation

Hybrid absorbersThe EMC testing system that Dyson has chosen is designed not just to meet, but to exceed the industry standards with which the company needs to comply. The chamber design optimises the performance to the very highest compliance levels and is proven by third party accredited test results.  The company chosen is able to provide local support within the UK, which is also a great benefit.  A similar installation has also been commissioned at Dyson’s South East Asia site. The combination provides the company with a global EMC test capability.

Ferrite tilesHaving evaluated the existing chamber, a team from EMC chamber specialist Microwave Vision Group (MVG) took a number of steps to meet the exact requirements of Dyson. “The existing system had been in place for just under 10 years, in which time there has been marked progress in industry developments and testing requirements”, says John Noonan, Managing Director of MVG’s EMC Division. “The project includes delivering an upgrade to refit new Hyperloss hybrid absorbers matched to the existing ferrite tiles.  With the vast changes in the complexity of Dyson’s products, we also needed to provide a chamber which would provide the company with a facility capable of testing for Electro Magnetic Compatibility (EMC) up to 2.7GHz.”

Scalon explained that the new facility will allow Dyson to test against full industry compliance requirements, therefore expanding both the capability and the performance of the chamber.  “Our new MVG EMC Chamber also gives us the capability to test to the standards specified by the industry, namely CISPR, IEC and FCC”, he said.

Maintaining confidentiality

Scalon believes that by having this new test facility on-site, it can maintain confidentiality during critical Dyson development processes. Once the prototype testing phase has been reached, having an in-house facility means that the company can test, check, modify and re-rest within a matter of minutes.  This provides a quick validation and the ability to check and verify compliance exactly when it is needed during the development and prototype process immediately, without the delays associated with outsourcing the test process. Without these delays, Dyson saves a significant amount of time as it doesn’t have to consider the lead times associated with sending the prototypes to test houses, which can be a particular burden during the iterative development phase. With a minimum running time of 8 hours per day, the test chamber is highly utilised and Scalon believes that the costs associated with running such highly utilised equipment in house are lower than those incurred by outsourcing.

In-house or out-source

Dyson gives intellectual property protection, flexibility and lower costs for high utilisation equipment as the reasons for performing EMC compliance testing in-house.  Four key things to consider when deciding on whether to test in house or to outsource:

Skills – EMC testing is part of the core business of a test house and all the necessary skills are there to support it. Performing in-house testing requires hiring the necessary staff with the right skill levels.

Flexibility – Pre-compliance testing can be a massive burden, particularly with complex products that have a high EMC profile and a consequent high risk of compliance test failure. In these cases, having access to in-house facilities provides greater scope for iterative testing – but at a high cost.

Cost – Outsourcing testing can be costly but reducing the number of design iterations and retests can significantly reduce that cost. On the other hand, semi-anechoic EMC test chambers can be high capital expenditure items.

Confidentiality – Some industries keep product designs more closely guarded than others. Consumer electronics, domestic appliances and the automotive industries are more likely to keep outsourcing to a minimum if they have the capability and budget to perform a task in-house.

Thumbnail guide to EMC standards

The EMC standards that a particular electronic product must meet depend on the product application (commercial or military) and the country in which the product is to be used. Manufacturers commonly impose EMC requirements that are even more stringent than the government standards.

International Standards

The International Electrotechnical Commission (IEC, operates closely with the International Organization for Standardization (ISO). Standards are written by a committee of the IEC (Special International Committee on Radio Interference, or CISPR). The IEC EMC standard is commonly referred to as “CISPR 22″. This standard has been adopted by the European Economic Community (EEC) in addition to several other countries. CISPR standards generally only relate to EMC emission test methods and limits.

Other IEC standards on EMC are mostly part of the IEC 61000 family.

ISO standards

There are a number of ISO standards on automotive EMC issues, such as ISO 11451 and ISO 11452 (road vehicles), ISO 13766 for earthmoving machinery and ISO 14982 for agricultural and forestry machinery.

Also, there is a range of European (EN) standards concerning unwanted electrical emissions and concerning immunity to electrical emissions. Certain VDE German standards for broadband and narrowband interference have also been adopted, including VDE 0875 and 0871.

Other European Standards

The European Telecommunications Standards Institute (ETSI) is responsible for standards involving information and communication technologies in Europe.

The European Committee for Electrotechnical Standardization (CENELEC) has as its mission to prepare voluntary electrotechnical standards that help develop a single European market.

American standards

The Federal Communications Commission (FCC) is charged with regulating interstate and international communications by radio, television, wire, satellite and cable. The United States (US) covers all types of unlicensed radio-frequency transmissions, both intentional and unintentional under Subparts A and B (Sections 15.1 through 15.199) of FCC 47 CFR Part 15, usually called just FCC Part 15, using the test procedures in ANSI C63.4.

The rest of FCC Part 15 (subparts C through H) deal with unlicensed devices specifically designed to emit radio waves (“intentional”), such as wireless LAN, cordless telephones, low-power broadcasting, walkie-talkies, etc.

Conducted emissions are regulated from 150 kHz to 30 MHz, and radiated emissions are regulated from 30 MHz and up.

Medical electronics and military electronics may have their own special requirements: EMC standards for equipment used by the US military are contained in MIL-STD 461, which is administered by the Department of Defense (DoD, Currently in revision F, it covers Conducted and Radiated Emissions and Susceptibility.

Jonathan Newell
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