Higher-wattage, pulse-start metal halide lamps
support and drive the trend toward white light and, along
with ceramic metal halide lamps, are expected to replace incandescent
and halogen sources.
Standard metal halide lamps in the 175-1000-W range that make
up 70% of existing applications are expected to be replaced
by either pulse start metal halide lamps or with the expanding
family of ceramic metal halide (CMH) lamps.
Low-wattage metal-halide lamps and all high-pressure sodium
(HPS) never used starting probes. Instead, they use a proven
pulse starter to start the lamps. This starting method is
not new--what is new is its use in higher-wattage metal halide
lamps.
Standard (probe-start) metal halide lamps use a bi-metal switch
inside the lamp to disconnect the starting electrode once
the HID lamp is warmed up, which is eliminated in the pulse-start
metal halide models. The best pulse-start lamp performance
results are from a new family of metal halide lamps based
on formed body arc tubes.
Formed body arc tubes feature higher fill pressures and more
uniform geometry than pinched arc seal tubes. Temperature
control is improved, which reduces lamp-to-lamp color shift.
Design changes result in up to 80% higher lumen maintenance,
up to 110 lm/W efficacy, 50% faster warm up and re-strike,
longer life, and more consistent lamp-to-lamp color.All in
all a better metal halide lamp.
