Effects of Harmonics on EMI/RFI Filters Operating Under Nonlinear LoadingConditions

摘要

Electromagnetic interference/radio frequency interference (EMI/RFI) power-linefilters are widely used in the Army for filtering unwanted signals on power lines serving sensitive equipment, particularly computers and communication gear. Typically, these loads are highly nonlinear and cause severe harmonic loading on the filters. Harmonics cause filter failure and shortened filter lifetimes. The objective of this research was to quantify the effects of harmonics and nonlinear loads on ENG/RFI filters and to recommend a derating factor for EMI/RFI filters in nonlinear load applications. EMI/RFI filters were purchased and placed in an experimental apparatus with a known source of harmonics. The filters were instrumented, and temperature data was recorded. A mathematical model of the filters was developed, and simulations were performed to predict filter failure. The results of the research indicate that filter capacity should be derated by 50 percent for filters that are being specified for nonlinear loading applications. Electrical distribution systems, Electromagnetic interference/radio frequency interference (EMI/RFI) filters, Nonlinear loads.