Technical information

2
3
5 Reducin
g
the watta
g
e o
f
hi
g
h intensity dischar
g
e lamps
5
.1
I
ntro
d
uct
i
o
n
High intensity discharge lamps generate light by excit
-
i
n
g
mercury an
d
ot
h
er meta
l
s w
i
t
hi
n an arc tu
b
e
i
nto
a plasma
g
enerated by the current
f
low between two
elec
tr
odes.
Di
sc
h
ar
g
e
l
amps must
b
e operate
d
w
i
t
h
a
b
a
ll
ast an
d
are rated
f
or a certain lamp wattage. Either conven-
t
i
ona
l
c
h
o
k
es or e
l
ectron
i
c
b
a
ll
asts can
b
e use
d.
To chan
g
e the nominal lamp watta
g
e o
f
a lamp, the
f
ollowin
g
g
eneral physical conditions are si
g
ni
f
icant
f
or
the resultin
g
e
ff
ects
:
•
The
e
l
ectro
d
e
s
o
f
dischar
g
e lamps are rated
f
or
a
certain lamp current. I
f
the current is too hi
g
h,
p
arts o
f
the electrodes melt and eva
p
orate. I
f
t
h
e current
i
s too
l
ow, t
h
e e
l
ectro
d
e
i
s o
p
erate
d
in cold state. This chan
g
es the mechanisms
f
or
releasin
g
electrons
f
rom the electrode with more
el
ectro
d
e mater
i
a
l
b
e
i
n
g
d
epos
i
te
d
on t
h
e tu
b
e
wall. Deviations in lam
p
current
f
rom the nomi
-
na
l v
a
l
ue
in
bo
th
d
ir
ec
ti
o
n
s
ca
n th
e
r
efo
r
e
cause
blackenin
g
of the arc tube wall with a decline
i
n
l
um
i
nous
fl
ux
,
to
g
ether with ne
g
ative e
ff
ects
o
n t
h
e
ligh
t co
l
our an
d
poss
ibl
y a
l
so on t
h
e ser-
vi
ce
li
fe.
• The partial vapor pressure o
f
the
f
illing particles
responsible
f
or
g
eneratin
g
li
g
ht depends on the
tem
p
erature o
f
t
h
e arc tu
b
e wa
ll
.
A
c
h
an
g
e
i
n
the arc tube wall temperature resultin
g
f
rom a
c
han
g
e in lamp watta
g
e in
f
luences the composi-
tion o
f
the
f
illin
g
in the plasma arc and thus the
electrical and
p
hotometric
p
ro
p
ertie
s
of
th
e
l
am
p.
•
A
t
high
er arc tu
b
e wa
ll
temperatures, t
h
e meta
l
s
d
o not recom
bi
ne w
i
t
h
t
h
e
i
o
did
es an
d
t
h
e
p
ure
m
etals can mi
g
rate into the wall
(
applies to quartz
a
rc tubes
).
5.
2
W
atta
g
e re
d
uct
i
on tec
h
n
i
ques
T
he following dimming methods are generally known
(
b
y
conventional means or electronic ballast
):
•
R
e
d
uct
i
on
i
n supp
l
y vo
l
ta
g
e
•
Phase
co
ntr
ol
:
l
ea
di
n
g
e
dg
e, tra
ili
n
g
e
dge
•
I
ncrease
i
n c
h
o
k
e
i
mpe
d
ance or
d
ecrease
i
n
l
amp
current
(
am
p
litude modulation
)
•
C
han
g
e in frequency for hi
g
h-frequency operation
5.
2
.1
R
e
d
uc
i
ng t
h
e supp
l
y vo
l
tage
A
re
d
uct
i
on
i
n supp
l
y vo
l
ta
g
e
b
eyon
d
recommen
d
e
d
limits
(
see sections 3.1.2 and 3.1.3
)
will decrease the
l
amp watta
g
e.
R
e
d
uc
i
n
g
l
amp watta
g
e resu
l
ts
i
n
d
e
-
crease
d
l
amp vo
l
ta
g
e an
d
re-
ig
n
i
t
i
on pea
k
vo
l
ta
g
e, an
d
is
g
enerally to a lesser extent than the supply volta
g
e.
Thi
s re
d
uct
i
on
i
n t
h
e
g
ap
b
etween t
h
e re-
ig
n
i
t
i
on pea
k
an
d
t
h
e supp
l
y vo
l
ta
g
e ma
k
es
i
t more pro
b
a
bl
e t
h
at
t
he
l
amp w
ill
g
o ou
t
.
Thi
s app
li
es part
i
cu
l
ar
l
y to a
g
e
d
l
amps w
h
ere t
h
e
l
amp vo
l
ta
g
e an
d
re-
ig
n
i
t
i
on vo
l
ta
g
e
have alread
y
increased.
Fi
g
. 25 shows, as an example, the behavior o
f
certain
l
amp types on re
d
uc
i
n
g
t
h
e supp
l
y vo
l
ta
g
e.
H
ere t
h
e
ratio o
f
re-i
g
nition volta
g
e to e
ff
ective supply volta
g
e
(
U
L
S
/U
S
)
has been standardized to 1 for 220 V suppl
y
vo
l
ta
g
e.
I
t can
b
e seen t
h
at w
h
en t
h
e supp
l
y vo
l
t
-
a
g
e decreases, this ratio
g
enerally assumes values o
f
g
reater t
h
an 1.
Thi
s a
l
so means t
h
at t
h
e
g
ap
b
etween
W
atta
g
e re
d
uct
i
on
h
as t
h
e
f
o
ll
ow
i
n
g
s
id
e e
ff
ects:
•
D
rop
i
n
l
um
i
nous
fl
ux t
h
rou
gh
bl
ac
k
en
i
n
g
of
t
hea
r
c
t
ube
•
C
han
g
e in color propertie
s
•
Reduc
t
io
n
i
n
se
rv
ice
life
1,4
1,3
1,2
1,1
1
0,9
140
150
160
170
180
190
200
210
220
230
240
250
260
ULS/US referred to the ratio at 220 V
Supply voltage US in V
ULS/US referred to the ratio at 220 V
HCI-TM 250 W/WDL
HCI-TS 70 W/WDL
HCI-TT 150 W/WDL
HQI-TS 150 W/WDL
HQI-TS 150 W/NDL
Fi
g
. 25: Relative chan
g
e in the re-i
g
nition peak
(U
L
S
)
to suppl
y
volta
g
e
(
U
S
)
referred to the ratio at 220 V fo
r
var
i
ous meta
l
h
a
lid
e
l
am
ps