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EMC/EMI testing is a critical step in the design and manufacturing processes of electronic devices. Various regulatory bodies, including the FDA, FCC, and ISO, have set specific limits on the emissions that can be released from an electronic device. These EMC (electromagnetic compatibility) regulations provide improved reliability and safety for anyone using electrical and electronic equipment because they assure the device does not interfere with the operation of other equipment or fail to operate as intended due to interference from others emissions. Failing to pass EMC compliance testing can result in fines and product recalls.So purchasing instruments that can spot potential EMC/EMI issues prior to EMC testing is worth the investment.
Though EMI and EMC are very similar, there are a few differences between the two.Talk To An Expert
What is EMI?
Sometimes called radio frequency interference (RFI), electromagnetic interference (EMI) occurs when electromagnetic energy disrupts the operation of an electronic device. The source of EMI can be man-made, such as other electrical devices like switch-mode power supplies, personal computers, or naturally occurring, such as electrical storms, solar radiation, or even cosmic noises.
What is EMC?
Electromagnetic compatibility (EMC) is the ability of a device to operate as intended in an environment with other electrical devices or sources of EMI without affecting those other devices. A device is said to be EMC-compliant when it does not influence the electromagnetic environment to the extent that other devices and systems are negatively affected.
What is EMI and EMC testing?
To ensure compliance with EMI and EMC national and international regulations, many companies employ the services of a specialized testing facility. Since these tests are expensive—even if the product fails—several companies perform EMC pre-compliance testing in-house. If they have a sophisticated enough lab, companies may also perform EMC compliance testing in-house.
EMC/EMI testing is typically divided into two categories: immunity testing and emissions testing.
Types of EMC tests
When electronics are submitted to EMC testing labs, there are many types of EMC tests these labs run. Generally speaking, EMC testing is divided into two categories: immunity testing and emissions testing.
Immunity testing is the process of transmitting RF energy onto a device under test (DUT) (also referred to as equipment under test or EUT) to determine if the DUT/EUT operates correctly when in such an environment.
Emissions testing is the process of measuring the RF emissions – both radiated and conducted – of a DUT/EUT to determine if its emissions levels do not exceed the limits defined by the appropriate standard. Emissions testing includes both radiated and conducted emissions tests.
Radiated emissions are the intentional and unintentional release of electromagnetic energy from an electronic device. A radiated test is performed to ensure emissions emanating from the DUT or EUT comply with the applicable limits.
Conducted emissions are the coupling of electromagnetic energy from a device to its power cord. Like radiated emissions, the allowable conducted emissions from electronic devices are controlled by different regulatory agencies and testing is performed to ensure emission levels are below the applicable limits.
EMI/EMC testing applications and standards
EMI/EMC testing is part of the product development process and testing is mandatory in most markets. Though all electronic devices are subject to EMC testing, the following are some of the most common applications for EMC testing and standards that devices and equipment need to meet.
|MARKET SEGMENTS||Equipment Type||STANDARDS|
|ISM MEDICAL||Industrial, scientific and medical equipment||CISPR 11||EN 55011||CFR Title 47 Part 18|
|Medical electrical apparatus||EN 60601-1-2|
|AUTOMOTIVE||Vehicles, boats and internal combustion engines||CISPR 12||EN 55012||CFR Title 47 Part 15(*)|
|Components and modules on board vehicles||CISPR 25||EN 55025|
|MULTIMEDIA||Sound and TV broadcast receivers||CISPR 13||EN 55013||CFR Title 47 Part 15|
|Information technology and telecommunications equipment (ITE)||CISPR 22 (superseded by EN55032)||EN 55022 (superseded by EN55032)|
|Professional audio/video/multimedia equipment||CISPR 32 (replaces CISPR 13 and 22)||EN 55032|
|APPLIANCES||Electrical devices, household appliances and tools||CISPR 14-1||EN 55014-1||CFR Title 47 Part 15|
|LUMINAIRES||Fluorescent lamps and luminaires||CISPR 15||EN 55015||CFR Title 47 Part 15|
|MILITARY||Military equipment and systems||MIL-STD-461G||DEF-STAN 59-411|
Take the mysteries out of EMI/EMC test setup
EMI/EMC pre-compliance testing doesn’t have to be hard or excessively time consuming. Based on customer feedback, Tektronix developed next-generation software with ease of use and functionality in mind, to provide pre-compliance testing for radiated and conducted measurements.
Setting up EMI/EMC pre-compliance testing starts with SignalVu-PC. This latest version of SignalVu-PC now comes with an additional option called EMCVu. EMCVu features an easy-to-use setup wizard, built-in standards and accessory setup with push-button selection capabilities. Whether you are setting up an Open-Air Test Site (OATS), or testing in your lab, EMCVu streamlines the capture and removal of ambient noise from your measurements to increase the accuracy of your pre-compliance tests without an anechoic chamber.
If you’re interested in trying a free 30-day trial of EMCVu, please click on the button below.
EMC testing labs
EMC-compliance tests are commonly done off-site prior to the production of a device. Open-air test sites, or OATS, are the reference sites used for most standards. They are especially useful for emissions testing of large equipment systems. However, RF testing of a physical prototype is more often carried out indoors, in a specialized anechoic chamber. Types of chambers include anechoic, reverberation, and the gigahertz transverse electromagnetic cell (GTEM cell).
EMC testing procedure and average pass rate
Roughly 50 percent of products pass their first EMC compliance test when pre-compliance isn’t considered, so it’s essential to understand the process and standards a device is tested to in order to increase your chances of success.
Know your standards
There are a variety of EMC standards that specify test procedures and limits for radiated and conducted emissions. These vary by country and type of equipment under test. The first step in testing is determining which standards apply to your product, and researching the testing procedures and limits required for compliance.
Conduct pre-compliance EMC testing
EMC compliance testing can take up to two weeks to complete—not including the time it takes to get your product into the test queue—and can cost up to $20,000 per submission. A failure in EMC compliance can result in expensive redesigns and product launch delays. And since nearly 50 percent of products fail their first EMC compliance test when pre-compliance isn’t considered, it’s likely that you’ll need to repeat your visit to the test house, multiplying costs over time.
Find an EMC testing lab
Once a product has gone through pre-compliance testing and passed the test with a sufficient margin, it needs to be formally certified by an EMC testing lab. Accredited labs are the gold-standard for EMC testing and choosing an accredited lab is always recommended—though not necessary—to ensure your device is ready to go to market. There are, however, some instances that require certification from an FCC-accredited lab, including devices that fall under the 'certification' authorization procedures.
How to pass EMC compatibility testing
EMC pre-compliance testing is a fast and affordable way to ensure products pass EMC tests the first time In the early development stages, design-for-EMC techniques are combined with diagnostics to build products with low susceptibility to both external and internal interference. Later in the development cycle, pre-compliance testing is used to catch compliance problems and improve the probability of a successful first pass of full EMC-compliance testing.
Additional benefits of pre-compliance EMC testing, include:
- Detects errors early, fixing potential issues
- Lowers testing and design costs
- Projects become more agile
- Lowers risk of failure and leads to assured compliance
- Addresses both over and under design and engineering
For a better understanding of how a Tektronix pre-compliance testing setup compares to an EMC testing lab, watch this short video.
Setting up a pre-compliance EMC test lab
When selecting a test site, rural areas, conference rooms, and basements are good options because they minimize external signals that might mask the DUT emission levels you are trying to measure. Other considerations for improving accuracy include having a good ground plane and reducing the number of reflective objects around the test area.
EMI and EMC testing products
The goal of EMC pre-compliance testing is to mimic the compliance test set up within an acceptable margin to uncover potential problems and reduce risk of failure prior to the expensive compliance test. EMC pre-compliance testing typically involves:
- Spectrum analyzer with quasi-peak detector
- Preamplifier (optional)
- Antenna with non-metallic stand for radiated emissions
- Line impedance stabilization network (LISN) for conducted test
- Power limiter for conducted test
- EMC near-field probes for diagnostics (optional)
- Oscilloscope with frequency and time correlation capabilities to assist in debugging (optional)
- EMC testing software
EMC testing resource center
Learn more about Tektronix EMC/EMI pre-compliance solutions and how to assemble a pre-compliance test setup, and get troubleshooting tips.
Get an estimate of EMC testing costs and the saving you can realize when you set up an in-house pre-compliance testing solution.
Download this customer case study to learn how the fast-growing start-up Eggtronic used a Tektronix real-time spectrum analyzer to enable an extremely fast scan procedure to ensure their products adhere to EMC/EMI standards.
Download this application note to learn how to address common design failures early when the costs of a re-design are minimal.
Find the right pre-compliance EMC testing solution for your operation today.Talk to an expert