Electromagnetic Interference from Fluorescent Lighting Operated with Solid-State Ballasts in Various Sites

Solid-state ballasts with 20-30 kHz fundamental frequencies were used to operate fluorescent lamps in office, screen room, and open-field sites. The test equipment and layout are described and the radiated and conducted electromagnetic interference (EMI) data are given for six commercially available ballasts from different manufacturers. EMI data from each location are presented that indicate the suitability of using an office site for future EMI measurements. Broadband EMI data are compared with data from a spectrum analyzer, which justifies the use of an RMS voltmeter in these measurements. A reduction in radiated EMI of 36 dB is achieved by replacing a strip fixture with an EMI-hardened fixture that has a wire grid embedded in its lens. Results of increasing lamp/antenna distance are given; we verify that, for distances greater than 1 meter, the radiated EMI amplitude drops off as a function of l/d³.