VEGA Z728 Zener barriers - Manual (Page 6)

6
Zener barriers - operating instructions
How to select the correct barrier
Subject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
Pepperl+Fuchs Group • Tel.: Germany +49 621 776-0 • USA +1 330 4253555 • Singapore +65 67799091 • Internet http://www.pepperl-fuchs.com
Da
te of issu
e
05/2
3
/03
7. The following points have to be clarified if special field
devices are used.
• If the field device is a 4 mA ... 20 mA transmitter: What load
in ohms can be connected to the transmitter so that it can
attain 20 mA as before?
• If the field device is a current/pressure converter: What load
can be connected to the controller card so that it can attain
20 mA as before?
• If the field device is a transmitter: How high is the load in the
safe area? (typically, resistances of up to 250 Ohm are used
in the controller)
Z ...
Barrier with replaceable back-up fuse
The introduction of a replaceable back-up fuse ahead of the
integrated fuse provides protection against faults which could
occur during the commissioning of the system. It is always arranged that the outer fuse will respond before the inner,
innaccessible fuse. The fuses used are specially intended for
use on barriers.
Type
Channels
Max. series
resistance
U
in
at 10 µA
U
in
max
Fuse rating External fuse Fuse supplied
by LITTLEFUSE
Ohm V V mA mA
Z715.F 1 106 13 13.6 100 63 217,063
Z728.F 1 327 27 28 80 50 217,05
Z728.H.F 1 250 27 28 80 50 217,05
Z765.F 2 106
106
13
13
13.6
13.6
100
100
63
63
217,063
Z779.F 2 327
327
27
27
28
28
80
80
50
50
217,05
Z779.H.F 2 250
250
27
27
28
28
80
80
50
50
217,05
Z787.F 2 327
36 + 0.9V
27
27
28
28
80
80
50
50
217,05
Z787.H.F 2 250
25 + 0.9V
27
27
28
28
80
80
50
50
217,05
Z960.F 2 64
64
6.5
6.5
9.5
9.5
80
80
50
50
217.05
Z961.F 2 106
106
6.5
6.5
8.1
8.1
160
160
100
100
217.1
Z966.F 2 166
166
10
10
11.7
11.7
100
100
63
63
217.063