Technical information

2
8
This is one o
f
the advantages o
f
the rectangular elec-
tronic ballast. As the zero crossin
g
f
or current is very
steep, the events o
f
limited current availabilit
y
are
ver
y
s
h
ort an
d
t
h
e p
l
asma
h
as
li
tt
l
e c
h
ance to coo
l
do
wn
.
Th
e
l
amp vo
l
ta
g
e an
d
t
h
e re-
ig
n
i
t
i
on pea
k
i
ncrease
w
i
t
h
pro
g
ress
i
n
g
l
amp a
g
e;
i
n a
ddi
t
i
on, t
hi
s paramete
r
a
l
so
d
e
p
en
d
s on t
h
e am
bi
ent tem
p
erature an
d
i
ncreas
-
es w
hil
e t
h
e
l
amp
i
s
h
eat
i
n
g
up.
Thi
s resu
l
ts
i
n w
h
at
i
s
known as cyclin
g
, where the lamp periodically
g
oes o
ff
an
d
on a
g
a
i
n.
Th
e re-
ig
n
i
t
i
on vo
l
ta
g
e
i
ncreases w
hil
e
t
h
e
l
amp
i
s
h
eat
i
n
g
up an
d
cont
i
nues to
i
ncrease unt
il
t
h
e
l
um
i
na
i
re
i
s comp
l
ete
l
y
h
eate
d
t
h
rou
gh
.
Thi
s
i
s w
h
y
it can happen that the lamp does not
g
o o
ff
until a
f
te
r
several or even many minutes o
f
burning time
.
Fi
g
. 31 shows a lamp with hi
g
h re-i
g
nition peak. A
f
ter
the zero crossin
g
, the current barely starts to
f
low. This
i
s w
h
y t
h
e vo
l
ta
g
e
l
oss across t
h
e c
h
o
k
e
i
s
l
ow an
d
nearly the entire volta
g
e supply
f
alls across the lamp,
with lamp voltage
f
ollowing supply voltage. The cur-
rent
f
low decreases even
f
urther
f
rom
p
eriod to
p
eriod,
so that conductivit
y
continues to
f
all; in the end, the
vo
l
ta
g
e requ
i
re
d
to re-
ig
n
i
te t
h
e p
l
asma
i
s
high
er t
h
an
t
h
e supp
l
y vo
l
ta
g
e
→
the lamp sta
y
s o
ff
a
f
ter the zero
crossin
g.
A
d
ec
li
ne
i
n t
h
e supp
l
y vo
l
ta
g
e can a
l
so cause t
h
e
l
amp to
g
o out.
I
t
i
s on
l
y w
h
en t
h
e
l
amp
h
as coo
l
e
d
down su
ff
iciently that re-i
g
nition is possible with the
n
ormal i
g
nition units. A
f
ter “cyclin
g
”
f
or a lon
g
time,
it is possible that the lamp will not i
g
nite at all
.
T
his
f
ault is not critical i
f
the i
g
nition unit does not
su
ff
er
f
rom the
f
requent i
g
nition attempts.
6
.
3
.
3
B
r
oke
n
lead
o
r
b
r
oke
n w
eld
T
his can be caused by material
f
ati
g
ue or extreme
m
echanical load. Normall
y
this is a non-critical
f
ault;
in very rare cases, a loose contact can cause high
i
n
d
uce
d
vo
l
ta
g
es.
Lamps with
g
as-
f
illed outer bulb
f
or supply volta
g
es o
f
4
00
V
ca
n
fo
rm
a
n
a
r
c
wh
e
n
a
l
ead
i
s
b
r
o
k
e
n
o
r
a
w
e
l
d
comes
l
oose.
D
ue to t
h
e current-
li
m
i
t
i
n
g
c
h
o
k
e, t
hi
s
arc can persist
f
or a longer period o
f
time and cause
the lamp to burst.
S
uch arcin
g
occurs both in lamps
w
i
t
h
an
ig
n
i
t
i
on un
i
t an
d
l
amps w
i
t
h
aux
ili
ary starter
electrode
(
lamps for i
g
nition at supply volta
g
e with a
watta
g
e of 2000 W
).
6
.
3
.4
L
ea
ki
n
g
outer
b
u
lb
M
ec
h
an
i
ca
l
i
m
p
acts can cause t
h
e outer
b
u
lb
to
l
ea
k
so that air penetrates.
G
iven the hi
g
h temperatures,
leads oxidize when oxy
g
en is present, causin
g
an
o
p
en in the circuit. This is a non-critical
f
ault; the lam
p
n
o
l
on
g
er
ig
n
i
tes.
Ig
n
i
t
i
on un
i
ts w
i
t
h
out cut-out can,
h
owever,
f
ail prematurely due to permanently
g
enerat-
i
n
g
ig
n
i
t
i
on pu
l
ses
.
6.3.5 Lamps that do not i
g
nite
T
his can result
f
rom o
p
en electrical connections within
the lamp or extreme a
g
in
g
and is actually a non-critical
f
ault. I
g
nition units without cut-out can, however,
f
ail pre
-
m
ature
l
y
d
ue to permanent
l
y
g
enerat
i
n
g
ig
n
i
t
i
on pu
l
ses.
Lamp voltage
Supply voltage
Lamp current
Re-ignition peak
Fig
. 30:
R
e-
ig
n
i
t
i
on pea
k
, supp
ly
vo
l
ta
g
e an
d
l
amp current
Supply voltage
Lamp voltage
Lamp current
Fi
g. 31:
A
l
amp goes out
b
ecause t
h
e re-
i
gn
i
t
i
on pea
k
i
s too high