A change in the flow of electric current produces electromagnetic radiation. The operation or usage of a particular device may be hampered if electromagnetic energy accidentally enters somewhere it is not wanted. Thus, a vital aspect of system and product design is the efficient management of electrical noise, both the susceptibility to and production of it. If noise sources are not properly detected and susceptibilities are not minimized at the time of preliminary design, later stages might require time-consuming and costly fixes. Thus, noise management initially involves gaining knowledge about the origins and the impact it might have in future. This blog will provide a handy guideline on how to best understand electromagnetic interference (EMI) noise management so that you can adopt the necessary precautions.
Compatibility and Interference
Power-system designs normally view noise in the form of electrical currents. This noise is also termed as radio frequency interference (RFI) or EMI. The performance of some devices is affected considerably by these currents. On the other hand, electromagnetic compatibility (EMC) may be described as the capacity of both the receptor and the source to suitably operate in a set electromagnetic environment. Noise currents are free-flowing, and when they exit the supply they are termed as “conducted emissions.” This path emits radiation that may lead to interference with other gadgets, which is the reason why power cables need to be routed regularly via ferrite chokes.
Ripple in converter output may often generate conducted EMI which is capable of deteriorating components within a power-system. Due to the lack of third-party standards, the designer has full discretion on how much is acceptable.
Switching, Capacitance, and Inductance
All electrical devices are capable of producing electrical noise when switched on and off. Even passive devices like rectifiers generate noise. Active devices switch at faster speeds, generating greater frequencies up to 30 MHz. The latter is the highest frequency as per commercial standards for the measurement of conducted interference. In case the front end comes with power factor correction (PFC) circuitry, additional EMI is produced by the PFC’s diodes and metal–oxide–semiconductor field-effect transistors (MOSFETs).
Why Is Grounding Important?
Quality grounding decreases the impact of noise sources by creating a low-impedance pathway to ground for electromagnetic interference currents. At the time of testing EMI qualifications, it is necessary that all noise currents are directed towards the earth instead of measurement equipment. Otherwise, this would affect both differential and common-mode measurements. A third-party specification generally enforces compliance with radiated and conducted emission standards.
EMI noise is harmful to electrical and electronic equipment and can greatly decrease device performance. Ideally, you should set up a good quality EMI noise grounding and shielding mechanism. Contact us now to learn more about our EMI shielding products.