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What's is
Capacitance:
HID lamp
Ignitor
provide a brief, high voltage pulse or pulse train to
breakdown the gas between the electrodes of an arc lamp.
Pulses can range from several hundred volts to 5KV.
Typical durations are in the µsec range. They are
usually timed to coincide with the peak of OCV. If they
are timed too early or too late, lamps may not start
reliably.
There are three basic
Ignitor
circuits in wide use. The simplest is a capacitor in
series with a voltage sensitive switch that connects
across the output of a lag ballast. It is used
internationally to start traditional metal halide lamps
on 220-230V 50 Hz mercury vapor ballasts. It generates
600V pulses and has the virtue of simplicity and low
cost.
The second consists of a capacitor charging circuit and
a voltage sensitive switch. It connects to a tap on the
output inductive element of the ballast and uses it as a
high frequency pulse transformer. This circuit works
with lag, HX, CWA, or regulated lag circuits. It is the
most common type of
Ignitor
used in North America and growing in popularity
internationally. It has the virtue of simplicity and low
cost. It requires the ballast insulation system to
withstand the pulse voltage; because it is tied to the
ballast, the distance the lamp can be mounted from the
ballast depends on pulse attenuation. Circuits that
generate wide pulses permit greater distance. These
circuits are generically referred to as "impulses."
The third circuit is similar to the first except that it
contains a pulse transformer. The virtues are that the
ballast insulation is not exposed to pulse voltage. The
Ignitor
can be mounted near the lamp while the ballast can be
remote. It can be used with any ballast type. This is
the most costly circuit to make, but allows the use of a
less expensive ballast. It is the most commonly used
circuit internationally. The
Ignitor
are referred to as superimposed
Ignitor
(SIP) because the pulse is superimposed on top of the
ballast OCV. |
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