Technical information

2
9
6
.
3
.
6
B
rea
k
age or
diff
er
i
ng wear o
f
t
h
e e
l
ectro
d
es
Breaka
g
e o
f
an electrode or di
ff
erin
g
wear in the elec-
trodes with choke operation can cause a
f
low o
f
as
y
m
-
metric current with D
C
com
p
onents, which can result
in the choke overheating. This effect of asymmetrical
con
d
uct
i
v
i
ty
i
s
d
ea
l
t w
i
t
h
i
n
g
reater
d
eta
il
b
e
l
ow
.
A
b
ro
k
en e
l
ectro
d
e
i
n a ceram
i
c
l
amp can cause
l
ea
k
s
in the arc tube as a result o
f
overheatin
g
capillaries,
with the e
ff
ects described above. In rare cases
,
a dis
-
c
h
arge attac
h
ment near t
h
e arc tu
b
e wa
ll
i
n ceram
i
c
l
amps can cause t
h
e arc tu
b
e to
b
urst
.
A
b
ro
k
en e
l
ectro
d
e
i
n a
l
amp w
i
t
h
quartz arc tu
b
e can,
a
f
ter a lon
g
er period o
f
time, cause the arc tube wall to
bulge and possibly leak or burst, i
f
the discharge still
p
ers
i
sts
.
6
.3.7
S
calin
g
of the base
/
socket
Particularly in the case o
f
old i
g
nition units without
automat
i
c cut-out an
d
a
g
e
d
l
amps or so
il
e
d
contacts,
high
trans
i
t
i
on res
i
stances can cause ox
id
at
i
on an
d
thus overheatin
g
o
f
the contacts. When i
g
nition pulses
persist
f
or a lon
g
er period o
f
time, i
f
lamps have
g
one
out because the re-i
g
nition peak is too hi
g
h or i
f
the
lamp has not i
g
nited, it is possible
f
or arc-over to oc
-
cur in the socket. I
f
scalin
g
has occurred, the socket
must
b
e rep
l
ace
d
as we
ll
as t
h
e
l
amp
.
V
ibrations can cause the lam
p
to become loose with
the possibility o
f
arc-overs and scalin
g
caused by the
resultin
g
poor contact. In these cases the usa
g
e o
f
a
l
amp
h
o
ld
er w
i
t
h
retent
i
on
d
ev
i
ce
i
s recommen
d
e
d
, as
described in the standard IE
C
60238 “Edison screw
h
o
ld
ers
”,
section 2.23 “Lamp holder with retention de-
vice”. The test conditions are described in section 12.14.
Suspending the luminaire on a chain attenuates
vibrations compared to suspending it on a rope.
6
.
3
.
8
B
urst
i
ng o
f
t
h
e
l
am
p
It is
g
enerally possible
f
or the arc tubes o
f
metal halide
lamps to burst. This is ver
y
rare
f
or ceramic metal ha-
lide lamps; the probability is
g
reater in lamps with a
very old quartz arc tubes. With pro
g
ressin
g
a
g
e, the
quartz crysta
lli
zat
i
on
i
ncreases, ma
ki
n
g
i
t
b
r
i
tt
l
e.
H
ow
-
ever, the lamps normally
f
ail by
g
oin
g
out
.
D
ur
i
n
g
operat
i
on, t
h
e arc tu
b
e
i
s un
d
er
g
reat pres
-
sure. When the arc tube bursts, fra
g
ments can fly at
g
reat spee
d
,
d
estroy
i
n
g
t
h
e outer
b
u
lb
w
h
en t
h
ey
hi
t
i
t.
When the outer bulb is broken a
f
ter the tube has burst
,
very hot
f
ra
g
ments o
f
the arc tube come into contact
w
i
t
h
t
he
lu
m
i
n
ai
r
e.
OS
RAM therefore strictl
y
differentiates between lamps
for o
p
en and closed luminaires. Lam
p
s for o
p
en lu
-
m
inaires have a mechanical sa
f
e
g
uard around the arc
tube to ensure that all
f
ra
g
ments remain intact within
the outer bulb should the arc tube burst.
C
ompliance
w
i
t
h
t
hi
s requ
i
rement
i
s ensure
d
t
h
rou
gh
i
n
h
ouse tests
at
OS
RAM, which are much more strin
g
ent than in
actual o
p
eration and in some
p
ublished standards,
f
or
exam
p
le, AN
S
I
S
tandards
.
T
his is the correspondin
g
picto
g
ram
f
or
lam
p
s of this kind as
p
er IE
C
62035.
A
s
i
t
i
s
g
enera
ll
y not poss
ibl
e to ru
l
e out t
h
e pos-
sibility o
f
the lamp burstin
g
f
or all other lamps, metal
h
a
lid
e
l
amps must
b
e operate
d
i
n c
l
ose
d
l
um
i
na
i
res,
w
hi
c
h
are
d
es
ig
ne
d
to conta
i
n a
ll
h
ot
f
ra
g
ments o
f
the lamp in the case o
f
it
burstin
g
. The correspondin
g
picto
g
ram
f
or lamp and luminaire accordin
g
to
IE
C
62035 is shown on the ri
g
ht.
S
ilicate
g
lass panes are recommended as a cover
screen. When
p
lastic screens are used, it is im
p
ortant
to ensure that the hot
p
arts o
f
the lam
p
will not melt or
set
f
ire to the screen should the lamp burst
.
Th
e cover screen must
b
e
b
ot
h
res
i
stant to tem
p
era-
ture change and break-proo
f
.
6
.
3
.
9
R
ect
if
y
i
n
g
e
ff
ect
High
i
ntens
i
ty
di
sc
h
ar
g
e
l
amps can assume an asym-
metrical mode (rectifying effect). There are various
p
oss
ibl
e causes
:
• Di
ff
erentl
y
heated electrodes
:
Thi
s
i
s t
y
p
i
ca
l
w
h
en t
h
e
l
amp starts,
b
ut
i
s nor-
mall
y
onl
y
short-lived. The D
C
component sends
t
h
e c
h
o
k
e
i
nto saturate
d
state, t
h
e ma
g
net
i
c
r
esis
t
a
n
ce
dec
r
eases
a
n
d
cu
rr
e
nt
is
li
m
i
t
ed
t
o
a
l
esser extent, s
h
own as an examp
l
e
i
n
Fig
. 32.
This e
ff
ect is described in the standards as
„
in-
rush current“
(
IE
C
61167
).
• M
a
l
fu
n
c
ti
o
n
of
o
n
e
of
th
e
e
l
ec
tr
odes:
This can be caused b
y
di
ff
erentl
y
worn elec
-
tro
d
es, or
i
n rare cases
by
a
b
ro
k
en e
l
ectro
d
e.
Th
e resu
l
t
i
s
l
on
g
er asymmetr
i
ca
l
l
amp current,
or if an electrode has broken off, a permanentl
y
as
y
mmetr
i
ca
l
l
amp current
.