Conducted RF emissions are electromagnetic disturbances (noise voltages and currents) caused by the electrical and electronic activity in an item of equipment, and conducted out of that equipment along its interconnecting cables, such as power, signal or data cables.
The use of exclusion zones to keep wireless transmission devices (WTDs) (e.g., radio walkie-talkies, cellular phones, etc) from being too close to instrumentation and control (I&C) equipment and system cabinets containing this equipment remains a primary concern in existing and advanced (future) nuclear power plants. In Part 1 of this article, a background and history of how exclusion zones were developed and implemented in these plants was presented along with their advantages and limitations. In Part 2, presented here, the elements of the exclusion zone strategy are discussed followed by the demonstration of a concept often used in studying the electromagnetic compatibility (EMC) immunity of modern electronic systems. This concept—called layered immunity—is key to understanding the parts of a system where EMC system immunity must be applied. The initial thought that readers must accept before proceeding to read and understand this concept described in this article is that system immunity involves other parts of the system besides just the immunity of the individual piece of equipment requiring protection.
An experimental validation of an electromagnetic band-gap (EBG) based common mode filter is given in this article. The proposed layout technique is based on planar EBG structures altered by removing the connecting bridges between adjacent patches. The patches are properly dimensioned for ensuring the presence of frequency notches at the frequencies that should be filtered in the common-mode transfer function. The notch frequency is associated with the first resonant mode of the patch.
In our ideal world, safety, quality and performance are paramount. However, the cost of the final component (which includes the ferrite) has in many cases, become the deciding factor. This article is written as an aide for the design engineer looking for alternative ferrite materials as a means to reduce cost.
