HPS light blinking
Gary Wilke
I have a high pressure sodium light that blinks off and on at night. I
have replaced the photo cell but it still blinks. Any suggestions?
Don Klipstein
Gary Wilke (gsw...@serv01.net-link.net) wrote:
: I have a high pressure sodium light that blinks off and on at night. I
This sounds like "cycling", a phenomenon in which an aging HPS lamp will
turn off for anywhere from several seconds to a few minutes, then turn
back on. This generally indicates an old bulb that needs replacing.
Why this happens:
1. The ends of the arc tube are blackened and absorb light. This
overheats the ends of the arc tube and vaporizes excessive quantities of
sodium. This changes the lamp's electrical characteristics until the
ballast cannot keep it running. The lamp then goes out, cools, then
restarts.
In recent years, the lamp manufacturers have largely solved this one.
However, this can still happen if the bulb is very old or the fixture
confines heat excessively, or reflects excessive light back to the arc
tube, or is otherwise "off" in design.
2. Deteriorated electrodes cause improper electrical characteristics
directly, or largely indirectly by producing excessive heat. Borderline
electrodes often work OK before the lamp is warmed up, since the current
is higher and gets the electrodes hotter. When the lamp is warmed up, the
current is lower and a weak electrode won't get hot enough to keep
working unless its voltage drop is excessive.
If the lamp cycles much more rapidly than once a minute, the cause is
almost certainly deteriorated electrodes. Regardless of how the bulb is
choosing to die, the problem is usually fixed by replacing the bulb.
- Don Klipstein (d...@misty.com or klip...@netaxs.com)
http://www.misty.com/~don/index.html (my home page)
http://www.misty.com/~don/light.html (my lighting index page)
http://www.misty.com/~don/dschlamp.html (discharge lamp document)