EMC for Product Designers

Tim Williams

• Publisher: Newnes
• Year: 2016
• ISBN:
  9780081010143
• Edition: 5
• Topic: Design
• Subtopic: Design industriale

EMC for Product Designers, Fifth Edition, provides all the key information needed to meet the requirements of the EMC compliance standards. More importantly, it shows how to incorporate EMC principles into the product design process, avoiding cost and performance penalties to meet the needs of specific standards that produce a better overall product. As well as covering the 2016 versions of the EU EMC and Radio Directives, this new edition has been thoroughly updated to be in line with the latest best practices in EMC compliance and product design. Coverage now includes extra detail on the main automotive, military, and aerospace standards requirements, as well as a discussion of the issues raised by COTS equipment in military applications.

New to this edition are chapters on functional safety, design and installation aspects of switchmode power converters with an introduction to EMC testing of integrated circuits, new details on CISPR 32/35, updates to new versions of the Directives DEF STAN 59-411, DO-160 and MIL STD 461, with more commentary on the implications and requirements of military and aerospace standards, and an added reference to CE Marking for military and problems of COTS.

In addition, new sections on IC emissions measurements per IEC 61967 are included, along with new coverage of FFT/time domain receivers, an expanded section on military/aerospace transients, special references to DO160 lightning, added material on MIL STD 461 CE101, RE101, and RS101, the latest practice in PCB layout with a discussion of slots in ground planes, current practice on decoupling, extended coverage of DC-DC converters and motor drives, and a new section on switching inverter (motor drives, renewable energy converters, etc.) installation, and the latest 2016 mandatory regulations of the RTTE and EMC Directives.

• Presents a complete introduction to EMC for product design from a practicing consultant in the field
• Includes short case studies that demonstrate how EMC product design is put into practice
• Provides the latest 2016 mandatory regulations of both the RTTE Directive and EMC Directive

Part 1

Legislation and Standards

Chapter 1

Introduction

1.1 What is EMC?

Electromagnetic interference (EMI) is a serious and increasing form of environmental pollution. Its effects range from minor annoyances due to crackles on broadcast reception, to potentially fatal accidents due to corruption of safety-critical control systems. Various forms of EMI may cause electrical and electronic malfunctions, can prevent the proper use of the radio frequency spectrum, can ignite flammable or other hazardous atmospheres, and may even have a direct effect on human tissue. As electronic systems penetrate more deeply into all aspects of society, so both the potential for interference effects and the potential for serious EMI-induced incidents increases.

Electromagnetic compatibility (EMC), then, is the absence of effects due to EMI. The definition of EMC, as it appears in the International Electrotechnical Vocabulary [169], is:

The ability of a device, equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment.

Some reported examples of electromagnetic incompatibility are:

• in Norfolk, various makes of car would “go crazy” when they passed a particular air defence radar installation – dashboard indicators dropping to zero or maximum, lights and engines cutting out;

• on one type of car, the central door locking and electric sunroof would operate when the car’s mobile transmitter was used;

• on another, the rear windscreen heater caused so much interference when switched on that it was impossible to listen to the car radio;

• new electronic push-button telephones installed near the Brookmans Park medium wave transmitter in North London were constantly afflicted with BBC radio programmes;

• residents in a housing estate at Liverpool, Australia suffered interference from an ABC broadcast transmitter across the road, interrupting phone calls, disturbing TV screens and turning electronic equipment on and off;

• near the BBC World Service transmitter at Rampisham, Dorset, residents have heard foreign voices through an electric organ and heard the signature tune through a toaster;

• interference to aeronautical safety communications at a US airport was traced to an electronic cash register a mile away;

• electronic point-of-sale units used in shoe, clothing and optician shops (where thick carpets and nylon-coated assistants were common) would experience lock up, false data and uncontrolled drawer openings;

• when a piezo-electric cigarette lighter was lit near the cabinet of a car park barrier control box, the radiated pulse caused the barrier to open and drivers were able to park free of charge;

• lowering the pantographs of electric locomotives at British Rail’s Liverpool Street station interfered with newly installed signalling control equipment, causing the signals to “fail safe” to red;

• Eurostar trains have never run north of London, at least partly because their motor noise interferes with safety signalling track circuits;

• a variable speed drive upgrade to ventilation fans in Helsinki trams interfered with the trams’ radios and other equipment along the route;

• a digital TV set-top box initiated an air–sea rescue operation in Portsmouth harbour by creating an emission on the distress frequency;

• two Navy warships nearly collided when the radar transmissions of the frigate HMAS Anzac disabled the steering of the minehunter HMAS Huon, Huon passing ahead of Anzac “at close range”.

Many other examples have been collected over the years; the “Banana Skins” column in the EMC Journal, collated by Keith Armstrong, has been a fruitful source, and the EMC group of the former UK Radiocommunications Agency commissioned an EMC Awareness web page introducing the subject [225], which also contains a number of examples. Here are a few issues in more detail.

1.1.1 Portable electronic devices (PEDs) in aircraft

Mobile cellular telephones have established themselves, through their sheer proliferation, as a serious EMC threat. Passengers boarding civil airliners have become familiar with the announcement that the use of such devices is not permitted on board. They may be less familiar with why this is regarded as necessary. The IFALPA International Quarterly Review reported 97 EMI-related events due to passenger “carry-on” electronic devices since 1983. To quote the Review:

… By 1990, the number of people boarding aeroplanes with electronic devices had grown significantly and the low-voltage operation of modern aircraft digital electronics were potentially more susceptible to EMI.

A look at the data during the last ten years indicates that the most likely time to experience EMI emissions is during cruise flight. This may be misleading, however. During the last three years, 43% of the reported events occurred in cruise flight while an almost equal percentage of events occurred in the climb and approach phases.

Of particular note: during the last three years the number of events relating to computers, compact disc players, and phones has dramatically increased and these devices have been found to more likely cause interference with systems which control the flight of the aircraft.

Recognising an apparent instrument or autopilot malfunction to be EMI related may be difficult or impossible in many situations. In some reported events the aircraft was off course but indications in the cockpit displayed on course. Air traffic controllers had to bring the course deviations to the attention of the crews. It is believed that there are EMI events happening that are not recognised as related to EMI and therefore not reported.

Particular points noted by the Review were that:

• events are on the rise;

• all phases of flight are exposed (not just cruise);

• many devices may cause EMI (phones, computers, CD players, video cameras, stereos);

• often there will be more than one device on a flight;

• passengers will turn on a device even after being told to turn it off^†;

• passengers will conceal usage of some devices (phones, computers);

• passengers will turn devices on just after take-off and just prior to landing;

• phones are a critical problem;

• specific device type and location should be recorded and reported by the crew;

• when the emitting EMI device is shut off, the aircraft systems return to normal operation (in the case of positioning errors a course change may be necessary);

• flight attendants should be briefed to recognize possible EMI devices.

In 2000, the Civil Aviation Authority carried out tests on two aircraft parked at Gatwick, which reinforces the ban on the use of mobile phones while the engine is running [64]. The tests revealed that interference levels varied with relatively small changes in the phone’s location, and tha...