former is connected to the luminaire. Each
kind of transformer requires a compatible
dimmer.
Magnetic-transformerlow-voltage dim-
mers are used for dimming luminaires
equipped with magnetic transformers. These
dimmers protect the lighting system from
the dc voltages and current surges to which
magnetic transformers are sensitive. Mag-
netic low-voltage dimmers are specially
designed to prevent dc voltage from being
applied to the transformer and to withstand
voltage “spikes” and current “surges.”
Equipment supplied with electronic
transformers requires the use ofelectronic-
transformerlow-voltage dimmers. Electronic
low-voltage dimmers are designed specifi-
cally for electronic transformers. They elimi-
nate the problems that occur in the interac-
tion between the transformer and the
dimmer when a magnetic low-voltage
dimmer is used with electronic transformers:
dimmer buzz, transformer buzz, lamp flicker-
ing, and radio frequency interference.
Electronic low-voltage dimmers com-
bined with electronic transformers have the
virtue of silent operation, although these
dimmers have a smaller capacity (up to 150
W) than magnetic low-voltage ones (up to
10,000 W).Fluorescent Lamps
Dimming fluorescent lamps requires the use
of special dimming ballasts, which replace
the standard ballast and must be compatible
with the dimming control device. Only rapid-ELECTRICITYFigure 11.10Effect of voltage variation on incandescent efficiency.