Theatre Design & Technology - Summer 1982 - 23

a 250 W output and operated with a 50 W ballast stabilizer
can be varied in light current by ± 80%, i.e., in this instance a
tolerance of 160% can be expected! This data assumes openburning of the lamp in still air and in a vertical position. Variations in external conditions such as lighting, ambient temperature, position of the lamp and wind can be expected to cause
surprises. One example is illustrated by the chart at the end of
this article showing the varying conditions prevailing with respect to a 250 W halogen high-pressure lamp with output reduced to 125 W. If the output of an individual, open-burning
lamp equals 100%, a variation in light current of approximately 48% can occur despite constant supply voltage and
the lamp ballast.

Figure 8: Decrease in Light Current at Underload

-----=:::r---

n.

t

'"

Conditions With Respect To A 250 W Halogen High-Pressure Lamp

Output
PL (%)

Light
Current
cD [%]

125W

100%

100%

110W

-88%

-78%

140W

-112%

-122%

145W

-116%

-126%

Output
PL , (Watt)

Operational Mode
Vertical, Open-Burning
At 20°C in Calm Air
Vertical, Open-Burning
At 20°C With Wind
Vertical, In An Enclosed
Lamp
Horizontal, Open-Burning
At 20°C in Calm Air

Figure 9: Permissable Variation in Light Current at Underload

90..----------....,.....---------,
A

-r----~ ---....

250W Sodium
High-Pressure Lamp
7{ A = Rated output 250W
B = 75W
C = 15W

B_

r-C__

~

1(00

0

2C00

~

4LW

W

Figure 10: Greater energy loss due to poor efficiency = light
yield. During control at 60W a 900% energy loss compared to
a standard 60W lamp.
20

+22%
4

Figure 11: Conditions as in Fig. 1 O. During control at 50W
375% energy loss. At 8 lumens per watt light yield poorer than
for incandescent lamps.
60

I

8
+57%

~

~1.2"1<

-18% i'-..

2
0

~

-36%

8

-77%

2
UJ
Power Consumption

~

'KXJ
W -.

50

~ 65

Ol

:::;

70

"-

~

·660/0

u

a;

'>
:E

60

:E 55
Ol
:::;

A = Standard Lamps
B = Controlled Lamps

50

40

50
-40%

250

200

0

50

0

I

/-

~

f--

A

~+31%

I

----..,

~ .......

'>
60

__

+14%

80

a;

lliU

--

75

~

70

150

Power Consumption (W)

+31%

t

u

200

-79%

Figure 13: An exception compared to other lamps. Light yield
increases with underloading. Lamp is not optimally designed.
During control at 20 W there is a 23% energy loss with respect to a standard lamp compared to a controlled lamp, i.e.,
a 31 % gain via controlled lamps. Diagram was determined
without the preheating of electrodes

90

~

\

A = Standard Lamps
B = Controlled Lamps

o250

0

t
"-

+375%

r-.....

10

Figure 12: Light yield poorer in the case of lamps shown in
Figs. 10 and 11. During control at 70W a 74% energy loss occurs.

A

-23°~

20

-8go~

m

~

~ r----..

--

"\%

B =Controlled Lamps

~
21~

----

+300/0

A =Standard Lamps

-56%' I'..

2:>0

A

30

~

4

o UJ

40

~

6f-

50W

125W
Fluorescent Lamp Ballast

::>l W

45
70

A = Standard Lamps

I

~

-23%

B = Controlled Lamps

i

60

50

40

Power Consumption (W)

---

~

_

20

10



Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 1982

Contents
Theatre Design & Technology - Summer 1982 - 1
Theatre Design & Technology - Summer 1982 - 2
Theatre Design & Technology - Summer 1982 - 3
Theatre Design & Technology - Summer 1982 - Contents
Theatre Design & Technology - Summer 1982 - 5
Theatre Design & Technology - Summer 1982 - 6
Theatre Design & Technology - Summer 1982 - 7
Theatre Design & Technology - Summer 1982 - 8
Theatre Design & Technology - Summer 1982 - 9
Theatre Design & Technology - Summer 1982 - 10
Theatre Design & Technology - Summer 1982 - 11
Theatre Design & Technology - Summer 1982 - 12
Theatre Design & Technology - Summer 1982 - 13
Theatre Design & Technology - Summer 1982 - 14
Theatre Design & Technology - Summer 1982 - 15
Theatre Design & Technology - Summer 1982 - 16
Theatre Design & Technology - Summer 1982 - 17
Theatre Design & Technology - Summer 1982 - 18
Theatre Design & Technology - Summer 1982 - 19
Theatre Design & Technology - Summer 1982 - 20
Theatre Design & Technology - Summer 1982 - 21
Theatre Design & Technology - Summer 1982 - 22
Theatre Design & Technology - Summer 1982 - 23
Theatre Design & Technology - Summer 1982 - 24
Theatre Design & Technology - Summer 1982 - 25
Theatre Design & Technology - Summer 1982 - 26
Theatre Design & Technology - Summer 1982 - 27
Theatre Design & Technology - Summer 1982 - 28
Theatre Design & Technology - Summer 1982 - 29
Theatre Design & Technology - Summer 1982 - 30
Theatre Design & Technology - Summer 1982 - 31
Theatre Design & Technology - Summer 1982 - 32
Theatre Design & Technology - Summer 1982 - 33
Theatre Design & Technology - Summer 1982 - 34
Theatre Design & Technology - Summer 1982 - 35
Theatre Design & Technology - Summer 1982 - 36
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