GE ConstantColor CMH G8.5 Datasheet page 4

Lumen maintenance
Lumen maintenance graphs show light output performance through life for statistically representative batches of lamps
operated under controlled nominal conditions with a 7 hours per start switching cycle. A common characteristic for all metal
halide lamps is a reduction in light output and a slight increase in power consumption through life. Consequently there is an
economic life at which lamp efficacy falls to a level when lamps should be replaced to restore design illumination levels.
Where a quantity of lamps are installed within an area, consideration should given to a group lamp replacement programme
to maintain uniform illumination levels. Curves represent operating conditions for a 7 hours per start switching cycle, but less
frequent switching will improve lumen maintenance.
Note: The representative curves are shown for Vertical Base-Up lamp orientation unless otherwise specified. Lumen
maintenance performance is significantly improved in the Horizontal burning position.
Lumen Maintenance 20W G8.5 3000K
100
95
90
85
80
75
70
65
60
0 2
Lumen Maintenance 35W G8.5 3000K
100
80
60
40
20
0
0 2 4 6 8 10 12 14
Burning time (thousand hours)
Lumen Maintenance 70W G8.5 3000K
100
80
60
40
20
0
0 2 4 6 8 10 12 14
Burning time (thousand hours)
6
4 6 8 10 12
Burning time (thousand hours)
Lumen Maintenance 35W G8.5 4200K
100
95
90
85
80
75
70
65
60
0 2 4 6 8
16
Burning time (thousand hours)
Lumen Maintenance 70W G8.5 4200K
100
80
60
40
20
0
16 0 2 4 6 8 10
Burning time (thousand hours)
Special power distribution
Spectral Power Distribution curves are given in the following diagram
Spectral Power Distribution [3000K]
70
60
50
40
30
20
10
0 0
380 430
Distribution of luminous intensity
The following diagrams show polar light intensity curves for lamp base-up orientation
Vertical plane polar intensity curve
135˚
120˚
105˚
10 12
90˚
75˚
60˚
45˚
C180
12 14 16
480 530 580 630 680 730
W W a a v v e e l l e e n n g g t t h h [ [ n n m m ] ]
Imax=170.13 cd at 100º
150˚ 165˚ I (cd) 165˚ 150˚ 135˚
120
120˚
90
60
105˚
30
90˚
30
75˚
60
90
60˚
120
30˚ 15˚ 0 15˚ 30˚ 45˚
C270 C0 C90
Spectral Power Distribution [4200K]
70
60
50
40
30
20
10
0 0
380 430 480 530 580 630 680 730
W W a a v v e e l l e e n n g g t t h h [ [ n n m m ] ]
Vertical plane polar intensity curve
Imax=170.13 cd at 100º
225˚ 210˚ 195˚ 180˚ 165˚ 150˚ 135˚
160
140˚
120˚
120
80
255˚ 105˚
40
270˚ 90˚
40
285˚ 75˚
80
120
300˚ 60˚
160
315˚ 330˚ 305˚ 0 15˚ 30˚ 45˚
I (cd)
C180 C270 C0 C90
7