Re: PHOTO-3D digest 1057

[bobh@xxxxxxxxxxxxx (Bob Howard)]

Subj: Overvoltagel Dr. T...viewer & 140 volts to 120 volt lamp.

There are of course voltage/lamp life tables which I can't lay my
hands on at the moment, but life is drastically affected, i.e. perhaps
1% over volatage equals 15% less life.
Common photofloods that give 3400 deg Kelvin, are essentially 60 volt
standard 2700 deg K. lamps run at 120 volts. As a result they have a
two hours life instead of 750 hours normal if run on 60 volts. Or a
household lamp made for 120 volts. In selling lamps they were stepped
in 5 volt design ranges..e.g. 105, 110, 115, 120, 125, 130, 135, 140
volts. The extemes needed on rotten or uncontrolled systems. If was
always a problems to get lamp distributors to grocery stores etc. to
order the right voltage for their community. New subdivisions had high
voltagle until more homes sold and load increased. Old parts of town
might have overextended facilities and low voltage. But the WRONG
voltage and lamp match meant short life if over voltage. BobH
(ex.Westinghouse lamp engineer)



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