When an electrical product is tested for electromagnetic compatibility (EMC), it is determined whether or not it will perform satisfactorily in the electromagnetic environment in which it will be used without causing unwanted electromagnetic disturbances to anything else in that environment. EMC is distinct from other safety considerations in that electromagnetic phenomena can be found in the regular operating environment of all electrical equipment.
In order to verify that all products are safe before they reach the end-user, EMC testing is performed at the design, development, and manufacturing stages of the product lifecycle. The test examines the correct selection of components as well as the proper construction of the device by the criteria of the applicable EMC regulations. When it comes to EMC type tests, they are typically far more demanding than ordinary production testing because they are intended to check a product’s safety design. Aside from that, the product sample must be energized before EMC testing.
Additional EMC testing for electrical products is required to secure international approvals and product certification marks for the products. Electrical devices, for example, must pass EMC testing and be in compliance with the EMC Directive 2014/30/EU to be approved for sale on the EU market and bear the CE marking.
The main types of EMC testing for achieving EMC compliance are:
- Radiated Emissions tests (EMI);
- Conducted Emissions tests;
- Flicker test;
- Radiated RF electromagnetic immunity test;
- Electrostatic discharge immunity test;
- Surge immunity test;
- Magnetic field immunity test;
- Electrical fast transient (EFT) test;
- Harmonic tests.
A good test strategy will include the following elements:
- a configuration, mode of operation, and monitoring mechanism that represent the worst-case situation from the standpoint of electromagnetic compatibility;
- a description of the hardware to be tested, including peripherals and I/O setups, is required;
- an indication of which external power and data I/O ports are required to be examined for each test method is also provided;
- tests that are required;
- a definition of the conditions for failure;
- how to keep track of, identify, and report failures;
- software, power, cooling, and other specialized requirements.
Once an EMC testing procedure has been completed and the product does not pass, the manufacturer has two options:
- To provide a new sample to the testing laboratory, on which all relevant tests are to be performed once more.
- Make all the necessary repairs and alterations to the sample that has previously been tested and have the lab redo only the sequence of EMC tests that the sample failed in the first place.
When it comes to ensuring that your device under test (DUT) will pass final compliance testing, pre-compliance is a low-risk, cost-effective option. Compliance product testing should not be delayed until the end of a product development cycle because of its high cost. It is necessary to reserve time in the compliance lab and redesign your DUT if it does not pass compliance testing. Pre-compliance testing is critical if you want to save money and avoid surprises during compliance testing.
History of EMC Testing
One of the first EMC regulations was developed in Europe at the beginning of the 20th century in response to specific concerns that arose as a result of the use of electrical devices.
Because of faulty electric bulbs in the neighborhood, other lights in the area began to “flicker.” This was back in the day when electric power systems were still in their infancy in cities like London, England, and other wealthy locales. To address this issue, the “Lighting Clauses Act” of 1899, which is considered to be the world’s first EMC legislation, was passed.
It is possible that Germany beat the United Kingdom to the punch with their 1892 “Law of the Telegraph in the German Empire,” which dealt with the effects of electromagnetic interference (EMI) disruptions on products and installations in the sphere of telegraph transmission. Because it was discovered that communication cables could have a negative impact on one another, this occurred.
Since 1938, the Federal Communications Commission (FCC) has set restrictions on transmitter emissions, and it has continued to increase its rules in response to the explosion in the number of transmitters and electronic devices during the following decades. Because the guidelines were becoming a little expansive and disorderly, the Federal Communications Commission standardized emission limitations for general applications in 1989.
The EMC directive, which was adopted by the European Union in 1992, was intended to unify criteria among member countries while also facilitating the transfer of electronic goods across borders.
The Future of EMC Testing
In the topic of EMC, there are a few new themes that should be noted:
Standardization of Rules and Regulations
There is a determined effort underway to standardize EMC testing criteria throughout the world, led principally by the International Electrotechnical Commission (IEC) (International Electrotechnical Commission). The International Electrotechnical Commission (IEC) develops standards that can be transferred by countries into their national standards, so, in principle, standardizing the EMC requirements across all the territories that adopt IEC standards. In the United Kingdom, for example, 85 percent of IEC standards are transferred into national standards.
Expansion of the requirements for testing
In some countries, such as the United States and Canada, only emissions testing is necessary at this time (unless your product falls under the scope of an industry-specific standard that calls out immunity testing). In Europe, on the other hand, both emissions and immunity tests are required.
Immunization testing has become mandatory in several nations, including Australia and New Zealand, in recent years, following the European Union’s example. According to the foregoing discussion, the increasing need for immunity testing is being driven by test labs, government agencies, and international standards organizations.