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Venture's
Technical Information
Capacitors
With
lag and HX ballasts, capacitors are needed to improve (input) power
factor. As a result, the number of lamps that can be operated on
a circuit nearly doubles. In large installations, power factor correction
is also required to avoid power quality problems and utility penalties.
Capacitors are integral components of CWA and regulated lag circuits;
they will not operate without capacitors. Both oil-filled (wet)
and dry-film capacitor technologies are commonly used with ballasts.
A means to discharge capacitors after power is turned off is a safety
requirement.
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Oil-filled
capacitors
Oil-filled
capacitors come in metal cases and are filled with a dielectric
fluid. They are rated up to 100°C, although 90°C
is the most common rating. They usually have two 1/4"
spade terminal lugs located on the top for connection with
the ballast. Most ballasts come with the mating terminals
already attached to the appropriate leads. Oil-filled capacitors
are very reliable and available in ratings up to 525V. For
some higher wattage HID ballasts, they are the only choice.
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Dry-Film
capacitors
Dry-Film
capacitors do not use a dielectric fluid. Originally, these
capacitors were limited to applications where voltages did
not exceed 330V. Recent advances have pushed this to 400V.
They are available in temperature ratings of 100°C and
have become an attractive alternative to oil-filled capacitors.
They are packaged in plastic housings which do not need to
be grounded and do not need any special clearances above the
terminals.
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