WHAT IS EMI/RFI?
Electromagnetic interference (EMI) or radio frequency interference (RFI) are unintentionally generated power that has a potential to interfere with other devices operating at high frequencies, such as radios, televisions or medical equipment. EMI/RFI levels are regulated by the FCC, and are usually reduced by filters, suppressor or other devices.
WHAT IS LAMP OPERATING FREQUENCY?
There are two types of operating frequencies associated with fluorescent ballasts: input and output frequency.
• Input frequency is delivered by the power company (utility). In North America, 60 Hz is the norm.
• Output frequency is sometimes referred to as the lamp operating frequency. This is the frequency that the ballast delivers to the lamp. Magnetic ballasts deliver 50/60 Hz; whereas electronic ballasts deliver a frequency greater than 20 000 Hz. Fluorescent lamps can accept either of these frequencies.
The FCC however, regulates certain ranges such as 30-40 kHz and 56-62 kHz.
STANDARD brand electronic ballasts comply with FCC regulations operating above 20 kHz but avoiding the restricted ranges.
DO BALLASTS CAUSE INFRARED INTERFERENCE?
Infrared energy is emitted by fluorescent lamps, and may interfere with infrared controls. To avoid any interference, either increase the distance of the fluorescent lamp and the infrared equipment or use a protective shield for the infrared receiver to minimize this effect.
WHY DO SOME BALLASTS MAKE NOISE AND ARE THERE QUIETER OPTIONS?
Fluorescent lighting fixtures produce a vibration (a slight buzzing sound) that originates in the core and coil assembly of magnetic ballasts. The buzzing sound can increase based on a variety of factors, including:
• The fashion in which the ballast is mounted in the fixture
• The design of the fluorescent lamp fixture
• Reverberating characteristics of the ceiling, walls, floors and furniture
• Ballast size: generally, the larger the ballast, the more humming it generates
To help sort through the variations, all ballasts carry a published sound rating of A, B, C, or D. These sound ratings are based on measurements of average ambient noise levels during conditions of normal occupancy. The following chart illustrates the average ambient noise level per application, and the corresponding recommended sound rating.