|
|
- Info
FAQs
- What causes some of the lights on campus to flicker at
times? The lights which flicker are the high pressure
sodium lamps. This type of lamp has a vapor of sodium inside,
which in the presence of a sufficient voltage, will emit energy seen as
light. This light has a yellowish color indicative of the sodium
vapor inside. As the lamp approaches the end of life
(insufficient vapors remaining for continuous operation), the lamp
cycles from off to on to off, appearing to flicker. It's a normal
phenomenon which tells us it is time to replace the lamp.
- Some lights are bright white and others have more of a
yellow glow. Why the difference? The
lights that appear to be a white light are called metal halide.
They contain a vapor of mercury with some materials called halides that
contain thallium, indium and sodium. When these materials are
excited by the presence of a voltage, their normal state is raised to
the point of luminescence and light is produced. Due to the
composition of the elements contained within, the light contains most
of the elements of the light spectrum and a white light is
produced. Metal halide lighting is the best choice for pedestrian
areas, as it provides a truer picture of colors and surroundings.
This is especially true of sports lighting. Those lights that
have a more yellow glow contain a vapor of sodium, which does not emit
the entire light spectrum in luminescence. The High
Pressure Sodium light source is much more economical and provides high
light output for power input and thus is used in parking lots and
roadway lights.
- What causes some of the "green boxes" on the campus to hum
and is any harmful raidation emitted from these? The
boxes you are referring to are transformers. The humming
noise is caused by "magnetostriction", or a very small movement of the
metal core of the transformer which is associated with the frequency of
the impressed voltage on the transformer assembly. There is no
radiation as the assembly is entirely encased and grounded. The
hum is only a physical indication the transformer is working
properly.
- What state and federal regulations do the Power Plants have
to meet? Our facilities rely on continuous air emissions
monitoring equipment to ensure compliance with all State and Federal
air quality requlations. For regulation information go to the North
Carolina Department of Environment and Natural Resources, Division of Air Quality website.
|
