Traditionally, higher wattage metal halide light bulbs (175,
250, 400, 1,000 and 1,500 watt) used probe start technology, which uses three
electrodes - a starter electrode and two operating electrodes - in the arc tube
to start the light bulb. Probe start metal halides have some inherent
disadvantages, such as high lumen depreciation over the life of the light bulb
due to tungsten sputtering off of the electrodes and blackening the arc tube
wall. In addition the warm-up period can be as long
as five minutes, depending upon light bulb type. If power is interrupted, even
briefly, the light bulb's arc will extinguish, and the light bulb needs time to
cool down before the arc can be re-started, in a typical probe start metal
halide, this could be anywhere from 10 to 20 minutes. This is a concern in some
lighting applications where prolonged lighting interruption could create manufacturing shut-down or a safety issue.
Pulse start technology, in part, was developed in
response to; The Energy Independence &
Security Act 2007 (EISA) a federal law, approved on December 19, 2007. A portion of this law mandates the efficiency
of metal halide ballasts from 150W - 500W and are manufactured (or import)
for sale in the United
States on or after January 1, 2009. Therefore, probe start metal halide bulbs are being phased out in the manufacturing of fixtures that utilize metal halide bulbs.
To achieve the required mandates, pulse start
metal halide light bulbs do not have a starter probe electrode. Instead they
have a high-voltage igniter that works with the ballast to start the light bulb
using a series of high-voltage pulses (typically 3 to 5 kilovolts). To change
from a probe start metal halide bulb to a pulse start metal halide bulb a new
ballast kit would be required to match the wattage of the pulse start metal
halide bulb.
The high pulses of voltage allow the light bulb to
warm-up and reach full lumen output faster than probe start light bulbs and
reduce hot restrike time; a pulse start metal halide light bulb needs only 5-7
minutes to restrike. Using an igniter also
reduces the tungsten sputtering by heating up the electrodes faster during
start-up; resulting in less lumen depreciation caused by tungsten blackening and
because the tungsten remains on the electrodes longer, the life of the pulse
start light bulb is longer than the probe start metal halide light bulb.
The results were a pulse start metal halide bulb with
improved lumens per watt and 10,000 more operating hours for Pulse
Start bulbs. Below is an example of the
improved lumens for a 400 watt bulb:
Probe Start 400w Metal Halide
23,000 Initial Lumens
@ 57.5 Lumens/watt
Pulse Start 400w Metal Halide
35,000 Initial
Lumens
12,000 more
Lumens
@ 87.5 Lumens/watt
To save energy and
still maintain or exceed existing light levels,
the following
bulbs could be used in place of a 400 watt bulb.
Pulse Start 350w Metal Halide
29,000 Initial Lumens
6,000 more
Lumens
@ 82.9 Lumens/watt
Pulse Start 320w Metal Halide
26,000 Initial Lumens
3,000 more
lumens
@ 81.3 Lumens/watt
Another difference between probe start metal halide bulbs and pulse
start metal halide bulbs is the degree of color shift. Probe start light bulbs have a color shift of
plus or minus 300K, whereas pulse start light bulbs have a color shift of plus
or minus 100K, which can still be considered a noticeable difference yet,
better than probe start light bulbs.
Also, some metal halide manufacturers now produce a bulb at 5,000K, with
a whiter, more natural light which allows a lower wattage bulb to have the perception of more light and can be used where color is important like retail and body shop painting applications
Contact
Premier Lighting for more information or to order pulse start metal halide bulbs and ballast kits.