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High Pressure
Sodium Ballast
How Does a High
Pressure Sodium Ballast Work?
By Keith Dooley
Light
A sodium vapor lamp is a
lamp that uses sodium to create light. It can come in a high pressure or low
pressure format.
High pressure lamps have
more components than low pressure and contain other substances such as mercury.
The lamp produces a clarity
of light that creates vivid color from objects illuminated by it.
The tube of a high pressure
sodium light is generally made out of aluminium oxide, due to its resistance to
the high pressure, and xenon, that is used as a starter for the light because
it won't react with the other gases.
Voltage runs to the light
through a ballast, which regulates the current.
Ballast
The arc of gas that extends
from one end of the tube to the other is created when ignited, and is made up
of metallic sodium and mercury vapor.
The temperature of the vapor
is controlled by the power supplied to the lamp. With higher power comes higher
temperatures and thus higher pressure in the tube, which creates more light.
The ballast is an inductive
ballast that helps regulate this power by keeping the current constant, instead
of the voltage.
Operation
The inductive ballast is
made up of a coiled wire. The coil creates a magnetic field inside when a
current is applied.
It stores the energy of the
current in the magnetic field it creates. This way it controls the output
current that continues on to the light.
The store of energy also
helps in the starting of the light when it is off, by sending an extra volt of
electricity when the current first starts into the coil.
Keith
Dooley has a degree in outdoor
education and sports management. He has worked as an assistant athletic
director, head coach and assistant coach in various sports including football,
softball and golf. Dooley has worked for various websites in the past,
contributing instructional articles on a wide variety of topics.
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