Electromagnetic Interference Caused by Parasitic Electric-line Current on a Digital Module in a Closed Cabinet

Abstract

This paper conducts an electromagnetic analysis of the closed cabinet used for instrumentation and control in nuclear power plants for the case of a parasitic electric-line current that is undesirably generated onto an interior digital module. Based on the Helmholtz equation in conjunction with both the separation of variables and superposition principle, we employed a mode-matching method to obtain the analytic solution to an electromagnetic interference problem. Using modal coefficients from a set of simultaneous equations by enforcing boundary conditions, we computationally derive electromagnetic-field distributions in terms of various geometric parameters. The results provide us with information useful for estimating the level of influence of the undesired current source on the adjacent digital modules. INDEX TERMS Electric-line current, electromagnetic interference, mode-matching method.

Analysis of Electromagnetic Interference Between Open Cable Trays

“…We employ the superposition principle to represent the EM fields; we consider two individual cases: with an electric-line current in open cable tray I and without an electric-line current in cable tray I enclosed (covered) by the PEC. For the case where the electric-line current exists at (x = x , z = z ), we only consider region III owing to the PEC cover, which results in an incident electric field as follows [15]− [17].…”

“…The results from the enforcement of the boundary conditions constitute a set of simultaneous equations to determine the unknown modal coefficients. Note that the specific procedure to build a set of simultaneous equations from enforcing the boundary condition is similarly presented in [17], [18]. In the Appendix, we append the boundary conditions at z = z 2, and describe the simultaneous equations derived from boundary conditions using a matrix equation.…”

“…In addition, we define the ratio T as the ratio of the length of the bottom plate to the length of the side wall (T = βλ/αλ = β/α). Based on the two-dimensional Helmholtz equation, the electric field (E y ) in cable tray II is expressed by a combination of the electric fields propagating in the +z and -z directions, as expressed in (17). The electric field at observation point 18), which is a function of the variables α and β, and the mode number m. As another expression of the electric field at P o , we can obtain ( 19) by applying the relationships of α = L/(λ (1+2T )) and β = T α to (18).…”

“…Before obtaining computed results regarding the EMI from an electric-line current, we first checked the convergence behavior of the resulting series solution for an electric field in each region. We examined the change in the relative error (η) at a specific observation point in each region corresponding to the increase in the maximum mode number (M = h) [17], [23]. The definition of the relative error at observation point…”

Analysis of decoupling performances of an isolation barrier using a mode‐matching method

“…1,2 On the other hand, as digital technology has seen more and more use in NPPs, concerns around electromagnetic (EM) interference caused by this digital equipment have arisen. [3][4][5][6] These concerns relate to maintaining the functionality of digital equipment, which is vital for various safety functions in NPPs, and should be guaranteed in any environment including those where electromagnetic coupling is a risk. As such, adequate precautions are required to reduce the risks of EM coupling negatively affecting digital equipment.…”