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 "impulsers."
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
ignitors are referred to as superimposed ignitors (SIP) because
the pulse is superimposed on top of the ballast OCV.
There are HID
lamps available internationally that incorporate internal ignitors.
The pulse voltage appears on the ballast output terminals. These
may not work with all ballast circuits, and could damage insulation.
Request technical support for help with these.
ignitors and ballasts are capable of continuous pulsing at maximum
rated case temperature.
operation (weeks to months) degrades ballast insulation and reduces
ballast life. Best practice is the timely replacement of failed
lamps to prolong ballast life. Ignitor case temperature limits must
be observed. There is little safety margin, so expect short ignitor
life if the limits are exceeded.
pulse start ballasts have distance limitations of 2 to 15 ft with
standard ignitors. Longer ballast-to-lamp (BTL) distances can be
attained with higher energy ignitors. These should not be used for
short range as they may damage ballast insulation and shorten ballast
life. Contact Venture for availability and technical support.