Cassette Style
100 Watt AC-DC Converters
S Series PFC
Edition 01/01.2001
22/27
Fig. 34
Paralleling of single output units using option T with the
sense lines connected at the load
Load
max. 5 units in parallel connection
+
–
Power bus
Module
Vo2
–
Vo2+
Vo1
–
Vo1+
T
Module
Vo2
–
Vo2+
Vo1
–
Vo1+
T
11037
Load
1
1
1
2
2
3
3
LS 4000
S+
T
Vo+
Vo
–
S
–
N
P
LS 4000
N
P
S+
T
Vo+
Vo
–
S
–
1
max. 5 units connected in parallel
1
Leads should have equal length and cross sections and should
run in the same cable loom.
2
Diodes recommended in redundant operation only
3
DC common point
11011
Fig. 35
Paralleling of double output units using option T with
Power bus.
E Inrush Current Limitation
The converters may be supplemented by an electronic cir-
cuit (option E, replacing the standard built-in NTC) to
achieve an enhanced inrush current limiting function.
Table 17: Inrush current characteristics with option E
Characteristics
U
i
= 230 V AC
LS
Unit
typ
max
I
inr p
Peak inrush current
–
25.3
A
t
inr
Inrush current duration
35
50
ms
15
I
i
[A]
10
5
0
–
5
–
10
0
20
40
60
80
t [ms]
t
inr
Capacitor C
i
fully charged
Normal operation
(FET fully conducting)
20
10
50
70
30
11002
Fig. 32
Inrush current with option E, U
i
= 230 V AC, P
o
= P
o nom
Precaution:
Subsequent switch-on cycles at start-up are limited to
max. 10 cycles during the
fi
rst 20 seconds (cold unit)
and at continuing on/off (T
C
= 95
°
C) max. 1 cycle every
8 sec.
Vo+
Vo
–
Vo+
Vo
–
Load
Vo+
Vo
–
11003
I
Control
C
FET
C
i
R
I
R
S
Rectifier
P
1
Fig. 31
Option E block diagram
T Current Sharing
This option ensures that the output currents are approxi-
mately shared between all paralleled modules and in-
creases system reliability. To use this facility, simply inter-
connect the T pins of all modules and make sure, that
pin 14, the S
–
pin (S 4000) or the Vo1
–
pins (S 5000) are
also connected together. The load leads should have equal
length and cross section to ensure equal voltage drops. Not
more than 5 units should be connected in parallel. If output
voltage adjustment is requested we strongly recommend to
use the R-input instead of option P, as with option P the re-
quired setting accuracy is dif
fi
cult to achieve. The output
voltages must be individually set prior to paralleling to
within a tolerance of 1...2% or the R pins should be con-
nected together.
Fig. 33
An example of poor wiring for connection in parallel