Technical information

12
The parallel capacitor has no in
f
luence on lamp
b
e
h
av
i
or
.
G
R
O
UP
CO
MPEN
S
ATI
O
N, where one
j
oint fixed ca-
pac
i
tor
i
s a
ll
ocate
d
to s
i
mu
l
taneous
l
y wor
ki
n
g
i
n
d
uc
-
tive consumers, similar to individual correction
(
motors
located close to
g
ether, dischar
g
e lamps). Here a
g
ain
t
h
e stra
i
n on t
h
e
l
ea
d
s
i
s re
li
eve
d
,
b
ut on
ly
up to t
h
e
p
oint o
f
distribution to the individual consumers. Un
-
der un
f
avorable conditions
,
resonance can be caused
i
n two-p
h
ase
g
r
id
s
.
C
ENTRAL
CO
MPEN
S
ATI
O
N
,
where a number of ca
-
p
ac
i
tors are connecte
d
to a ma
i
n or su
b
-
di
str
ib
ut
i
on
stat
i
on.
Thi
s
i
s t
h
e norma
l
proce
d
ure
i
n
l
ar
g
e e
l
ectr
i
ca
l
systems w
i
t
h
c
h
an
gi
n
g
l
oa
d
.
H
ere t
h
e capac
i
tors are
contro
ll
e
d
by
an e
l
ectron
i
c contro
ll
er w
hi
c
h
constant
ly
analyzes the demand
f
or wattless power in the
g
rid.
This controller switches the capacitors on or o
ff
to cor
-
rect the current wattless
p
ower o
f
the total load and
t
h
us re
d
uce overa
ll
d
eman
d
i
n t
h
e
g
r
id.
C
a
p
acitor for
p
ower factor correction values are
stated
f
or ever
y
lamp t
y
pe in the Technical In
f
ormation
and can also be calculated usin
g
the
f
ollowin
g
equa-
t
io
n
.
C
PF
C
in F
C
apacitance of the capacitor for power
fac
t
o
r
co
rr
ec
ti
on
U
S
i
n
V
R
ate
d
supp
l
y vo
l
ta
ge
f
S
in Hz
S
uppl
y
frequenc
y
I
L
i
n
A
L
amp rate
d
curren
t
P
W
in W Total active power
(
lamp rated wattage plus
choke loss watta
g
e
)
ϕ
K
Tolerable or desirable
p
hase di
ff
erence be
-
tween the
f
undamental waves o
f
the suppl
y
vo
l
ta
g
e an
d
t
h
e supp
l
y current
.
But this onl
y
corrects the power
f
actor
f
or the
f
unda
-
m
ental wave. Phase di
ff
erence remains
f
or distortion
,
i
.e. t
h
e
h
armon
i
c waves,
b
etween current an
d
vo
l
ta
g
e.
For this reason, the overall power
f
actor can also onl
y
reac
h
va
l
ues
b
etween 0.95 an
d
0.98
i
n
p
ract
i
ce
.
A
hi
g
her level o
f
harmonic waves can cause resonance
e
ff
ects and destro
y
the lamp. A power
f
actor close to 1
is
t
o
be
a
v
oided
as
t
his
ca
n
cause
r
eso
n
a
n
ce
be
tw
ee
n
t
h
e c
h
o
k
e an
d
correct
i
on capac
i
tor
.
W
hile a dischar
g
e lamp is startin
g
up, the power
f
actor
u
nder
g
oes si
g
ni
f
icant chan
g
es in value. A
f
ter i
g
nition,
the lamp volta
g
e is still very low with current hi
g
her
than in stead
y
state. This is wh
y
the power
f
actor in
this state is still low (inductive). While lamp volta
g
e
increases and the lamp current
f
alls, the power
f
acto
r
in
c
r
eases
t
o
it
s
n
o
min
a
l v
a
l
ue
of
0
.
85
–
0
.
9.
A
s dischar
g
e lamps a
g
e, it is normal
f
or lamp volta
g
e to
increase, causin
g
the lamp current to
f
all accordin
g
to
the ballast curve. Because the capacitor
f
or power
f
actor
correction is rated
f
or a s
p
eci
fi
c lam
p
and choke current,
the power
f
actor varies accordin
g
to lamp current. For an
extreme
l
y
hi
g
h
l
amp vo
l
tage, t
h
e c
h
o
k
e current
i
s so
l
ow
t
h
at ca
p
ac
i
t
i
ve current excee
d
s t
h
e
i
n
d
uct
i
ve current an
d
t
h
e comp
l
ete c
i
rcu
i
t
b
ecomes capac
i
t
i
ve
.
Under certain conditions, audio
f
requenc
y
central con-
tro
l
systems
h
ave to
b
e cons
id
ere
d
d
ur
i
n
g
i
nsta
ll
at
i
on.
In these cases, suitable audio
f
requenc
y
attenuation
chokes are to be provided. This kind o
f
s
y
stem is still
sometimes used for day
/
ni
g
ht circuits in street li
g
htin
g
,
although directional radio systems are
f
inding increas-
i
n
g
use
h
ere
.
3.2 Electronic control
g
ear
(
E
CG)
To
g
ether with conventional ballasts, the use o
f
elec
-
tron
i
c
b
a
ll
asts
h
as meanw
hil
e
b
ecome w
id
e
ly
accepte
d
practice, particularly
f
or interior li
g
htin
g
.
Electronic ballasts o
ff
er clear advanta
g
es compared
to convent
i
ona
l
b
a
ll
asts.
Th
e ma
i
n a
d
vanta
g
es
i
nc
l
u
d
e
in particular simplified handlin
g
(
e.
g
. li
g
hter ballasts
)
,
l
ower ener
g
y consumpt
i
on, a pos
i
t
i
ve
i
mpact on
l
amp
service li
f
e and li
g
ht quality, and, last but not least,
controlled and reliable shutdown o
f
lamps at the end
o
f
the service li
f
e
.
Basicall
y
, most o
f
the technical in
f
ormation provided in
t
hi
s manua
l
a
ppli
es to
b
ot
h
convent
i
ona
l
b
a
ll
asts an
d
electronic ballasts. This re
f
ers
f
or example to wirin
g
requirements, wattage-reduced operation o
f
MH lamps
or instructions
f
or luminaire desi
g
n
.
But in addition
,
there are also considerable di
ff
erences
b
etween operat
i
on on an e
l
ectron
i
c or ma
g
net
i
c
b
a
ll
ast.
The
f
ollowin
g
section brie
f
ly explains the main di
ff
er
-
e
n
ces
a
n
d
th
e
ir
effec
t
s.
3.2.1 Structure and functionin
g
of an electronic
ballas
t
Electronic ballasts mainl
y
consist o
f
units with rect-
a
n
g
u
l
ar current an
d
vo
l
ta
g
e.
I
n pr
i
nc
i
p
l
e,
i
t
i
s a
l
so
possible to operate the lamps with hi
g
h-
f
requency
sinusoidal current similar to the
f
luorescent lam
p
. In
a
n
y
case,
i
t
i
s
i
mportant to ensure t
h
at no acoust
i
c
resonances occur as t
h
ese ma
y
resu
l
t
i
n arc
i
nsta
bili
t
y
(
lam
p
flicker
)
and in severe cases, lam
p
ru
p
ture
.
3.2.2
S
ervice life and tem
p
erature
T
here is a si
g
ni
f
icant di
ff
erence between conventional
a
n
d
e
l
ectron
i
c
b
a
ll
asts part
i
cu
l
ar
l
y w
i
t
h
re
g
ar
d
to t
h
e
se
rvi
ce
li
fe
a
n
d
th
e
rm
a
l
be
h
a
vi
o
r
of
th
e
u
nit
s.
()
⎟
⎠
⎞
⎜
⎝
⎛
×−−
××
×××
=
KWWL
S
SS
PP
I
U
Uf
C
ϕ
π
tan
2
1
22
2
2
PFC
E
q. 4.
3