What is EMS immunity testing? EMS (Electromagnetic Susceptibility) refers to the ability of machinery, equipment, and systems to withstand electromagnetic interference present in a given environment, i.e., their electromagnetic sensitivity.
EMS encompasses related disciplines including Electrostatic Discharge (ESD), Radio Frequency Immunity (RS), Electrostatic Fast Transient Burst Immunity (EFT), Surge Immunity, Voltage Dip and Interrupt Immunity, among others.
EMS/Electromagnetic Immunity
· Conducted Susceptibility (CS) Testing: EN 61000-4-6
· Radiated Susceptibility (RS): EN 61000-4-3
· Electrostatic Discharge (ESD): EN 61000-4-2
· Electrical Fast Transient/Burst (EFT): EN 61000-4-4
·PFMF (Power Frequency Magnetic Field) Immunity Test: EN 61000-4-8
- Surge Immunity Test: EN 61000-4-5
- PQF (Voltage Dips, Interruptions and Variations) Immunity Test: EN 61000-4-11
EMC testing, also known as Electromagnetic Compatibility (EMC) testing, refers to the comprehensive assessment of an electronic product’s level of electromagnetic interference (EMI) and its immunity to such interference (EMS). It stands as one of the most critical indicators of product quality. The EMC measurement system comprises both the test site and the test apparatus.
The purpose of EMC testing is to evaluate the impact of electromagnetic radiation emitted by electrical products on human health, public grid systems, and other normally functioning electrical equipment.
General Principles of EMC Design:
EMC design should form an integral part of the overall design for any electronic device or system. This approach proves far more cost-effective than attempting to achieve compliance through other methods. Key EMC design techniques include: electromagnetic shielding methods, circuit filtering techniques, and grounding design – with particular attention to ground plane connections.
Firstly, the foundation of excellent EMC design lies in the application of sound electrical and mechanical design principles. This encompasses reliability considerations, such as meeting design specifications within acceptable tolerances, employing sound assembly methods, and utilising various evolving test techniques.
Generally, the devices driving modern electronic equipment are mounted on PCBs. These devices comprise components and circuits that are both potential sources of interference and sensitive to electromagnetic energy. Consequently, PCB EMC design represents the next most critical aspect of EMC design. The placement of active components, routing of printed lines, impedance matching, grounding design, and circuit filtering must all be considered during EMC design. Certain PCB components may also require shielding.
Secondly, internal cables are typically employed to connect PCB boards or other internal sub-assemblies. Consequently, the EMC design of internal cabling—including routing methods and shielding—is crucial for the overall EMC performance of any given device.
Following completion of the PCB EMC design and internal cable design, particular attention should be paid to the enclosure’s shielding design and the treatment of all gaps, perforations, and cable feed-throughs.
Finally, input and output power supply filtering and other cable filtering issues should also be given significant consideration.
The foundation of EMC design lies in sound electrical and mechanical design principles, including meeting design specifications within acceptable tolerances, good assembly practices, and the various testing techniques under development. During the PCB design phase, factors such as the placement of active components, printed trace routing, impedance matching, grounding design, and circuit filtering must be considered. For internal cabling, routing methods and shielding design are also critical. Furthermore, the enclosure’s shielding design and the treatment of all gaps, perforations, and cable feed-throughs require significant attention. Finally, filtering for input/output power supplies and other cables should be thoroughly addressed.