EMI/EMC testing indicates to engineers whether a device is compatible with its electromagnetic environment and determines whether the device will produce electromagnetic interference, or EMI, in real-world situations. In a world without EMC testing, the risk of helicopters falling out of the sky, respirators going silent, or your cell phone losing its signal would increase. All of these machines rely on technology which can be disrupted by rogue electromagnetic energy, and thus undergo EMC testing to fulfill requirements for IEC, CISPR, and MIL-STDs (military standards) and achieve EMI compliance.
What is EMC?
Electromagnetic compatibility, commonly referred to as EMC, is a branch of electrical engineering focused on EMI/EMC testing. Jets, gaming systems, and automobiles, for example, all need to be configured to protect against harmful electromagnetic interference, or EMI. Perhaps even more worrisome, products themselves may produce electromagnetic interference. A device which interrupts cell tower signals or damages airplanes could cost companies millions in fines or lawsuits.
EMI/EMC Testing Procedure
- Find the Standards. “Which standards apply to my product?” is the first question you should ask yourself. Varying between product type and geography, standards can be difficult to define or pin down and missing an EMC standard can be disastrous for manufacturers. Contact an EMC test lab and determine which standards you need to meet before sending your product in or develop an EMC test plan yourself if you’re familiar with the requirements. To do your own research, visit ATEC’s standards page, which will give you detailed outlines of each standard, and call +1 (800) 404-2832 for any questions.
- DO-160 Standards
- IEC-61000 Standards
- MIL-STD Standards
- Perform Pre-Compliance Testing. You want your products to possess flawless EMI immunity and produce no more accidental energy than regulations require before they are formally tested. Test your devices in full-compliance test sites like anechoic chambers or RF shield enclosures. Rent full-compliance testers like EMI receivers. Depending on the product being tested, be sure to test for both the product’s immunity to EMI and the EMI emissions it generates, which are discussed in the sections below. Renting fully EMC-compliant test equipment from ATEC will save you money and time in the pre-compliance process—we are ISO-9001 certified and ISO 17025 accredited in calibration by the A2LA.
- Choose an EMC test lab. Be sure to choose an EMC lab that is A2LA 17025 accredited. EMC accreditation is essential to establishing the validity of your testing when placing products on the market. Because of this, though, EMC labs are busy. Book your appointment months in advance, and plan out your pre-compliance testing so you can avoid expensive rescheduling.
To assess the EMC of a device or system, technicians perform four basic types of tests: radiated immunity, radiated emissions, conducted immunity, and conducted emissions.
Radiated Immunity - Radiated immunity testing analyzes how a device will perform when exposed to the electromagnetic energy it will encounter in its environment.
Radiated Emissions - Radiated emissions tests measure the electromagnetic disturbance a device generates. Technicians want to ensure that the product’s emissions are below the relevant limits for its size and power.
Conducted Immunity - Gauges the response of a piece of equipment to electromagnetic energy that generates within another source and then accidentally is conducted along a cable or other conductor to the device under test.
Conducted Emissions - Measures the level of internal electromagnetic energy which may travel along a conductor and inflict EMI on other systems.
Completing these tests calls for specialized products depending on the application. For example, the EMSCAN EHX+
is an EMC/EMI diagnostic tool featuring a built-in spectrum analyzer. EMSCAN EHX+ models allow engineers to visualize radiated emissions and even identify faults, reducing the testing time of the average near field probes by two orders of magnitude. A product like the EHX+ saves time and money and offers precise data for analysis.
EMI/EMC Testing Equipment
Engineers often send their products to be tested and then certified by labs with EMC accreditation. However, in a 2007 study, researchers found that 50% of devices fail EMC testing on the first try. With the products below, you can conduct EMI/EMC testing in-house, running multiple tests to fine-tune your products’ compatibility before sending them to be certified by a lab.
Conducted Emissions Testing
Conducted Emissions testing detects the presence of internal emissions of electromagnetic energy, which grow in strength as they are conducted along a power or signal conductor, generating interference. The conductor thus acts as an antenna that is “accidentally transmitting.” Generally, this testing method is applied to simulate internal interference found in power leads and antenna terminals. Learn more about conducted emissions here
Standards Relevant to Conducted Emissions
Conducted Immunity Testing
A conducted immunity test monitors a device’s resistance to external interference generated by a conductor of EMI, like a power or signal cable. Engineers perform conducted immunity testing to discover how the instrument in question reacts to conducted EMI, and how it can be augmented to enhance its immunity. Learn more about conducted immunity here.
Standards Relevant to Conducted Immunity
Radiated Emissions Testing
Radiated emissions testing measures the electromagnetic energy a product generates, simulating the interference a device may produce in its environment. Currents and switching voltages within all digital circuits unintentionally generate EMI. The challenge for engineers, then, is to mitigate this interference to the required levels. Radiated emissions testing is conducted either in open area test sites or in anechoic chambers. Learn more about radiated emissions here.
Standards Relevant to Radiated Emissions
- MIL-STD-641 RE101
- MIL-STD-641 RE102
Radiated Immunity Testing
Radiated immunity testing simulates a device’s interactions with other electromagnetic fields it may encounter. Cell phones, radios, motors, and a plethora of other devices may emit EMI that causes damage or interferes with the signal of the device under test. RF amplifiers play an essential role in these tests because to generate an electromagnetic field which effectively mimics conditions for standards, the signal needs precise amplification. Learn more about radiated immunity
Standards Relevant to Radiated Immunity
- American National Standards Institute (ANSI)
- IEEE EMC Society (IEEE)
- Society of Automotive Engineers (SAE)
- Electromagnetic Compatibility Industry Association (UK) (EMCIA)
- Comité International Spécial des Perturbations Radioélectriques (CISPR) – Special International Committee on Radio Interference
For manufacturers in many fields, testing the electromagnetic qualities of a product is an essential step in production.
- Medical Equipment
- EMC testing is a critical step in the manufacturing of medical devices. If a medical device is unable to function well with the electrical systems around it, the device may pose a risk to patients. The FDA mandates that all medical devices are EMC tested according to IEC standards.
- Military / Aerospace
- Military equipment is subject to rigorous testing standards which call for electromagnetic susceptibility and emissions testing, among other requirements. MIL-STD-461 is a common standard for automobiles, aircraft, spacecraft and other vehicles and instruments which may be at risk of emitting or being affected by electromagnetic energy.
- Consumer Goods
- Everything from your iPhone to your laptop and Xbox undergo EMC tests, especially devices which connect to Wi-Fi and have the potential to emit far-reaching EMI. FCC standards call for comprehensive testing of consumer technology before allowing products to enter the marketplace.
- Manufacturers of cars and other automotive machines require EMI/EMC testing for both their components, including parts like engines and radios, and the automobiles as a whole. BMW, Mercedes, and Volkswagen are just a few of the car companies with such standards.
- Component testing is an expansive facet of EMC. Semiconductors in particular are utilized in nearly all computerized products, and due to their capacity for electromagnetic emission, require testing to ensure they don’t interfere with other devices.
What is EMI/EMC Testing? Test Equipment+