VEGA VEGADIF 34 … 51 - Manual (Page 30)

30 VEGADIF 34 … 51
20094-EN-030731
1
+
2
-
3
4 ... 20 mA
+
-
+
- =
~
U
Kl
U
S
VEGADIS 11 Processing, e.g.
indicating instru-
ment
e.g. Ex-separator
VEGATRENN
149 Ex
4…20 mA
Ex area Non-Ex area
Terminals
VEGADIF
Ex application with power supply via VEGA
non-Ex signal conditioning instrument
with safety barrier type 145
The processing is done by the signal condi-
tioning instrument in the non-Ex area.
Note
- Carry out the adjustment only with con-
nected safety barrier (reason: the current
consumption of approx. 300 µA is consid-
ered).
- When connecting a VEGADIS 11 Ex the
regulations for wiring of intrinsically safe
circuits should be noted.
Determination of the cable length in the
ia IIC circuit
The sum of the inner capacitances and induct-
ances of the components must not exceed the
max. permissible values of the ia IIC circuit.
Example:
ia IIC circuit Pressure 1 pce. Cable 1)
max. total transmitter overv. arrester L
int
/C
int
L
ext
/C
ext
L
int
/C
int
L
int
/C
int
0.5 mH 0.2 mH 0.13 mH 0.17 mH
56 nF 11.2 nF 1 nF 44.8 nF
1
+
2
-
3
4 ... 20 mA
+
-
U
Kl
VEGAMET in
non-Ex version
Safety barrier
type 145
Ex-area Non-Ex area
Terminals
VEGADIF
1) Typical values for unscreened two-wire cables:
L‘ = 0.00065 mH/m; C‘ = 0.00012 nF/m
3.4 Ex applications
Applications in Ex areas require the use of
approved instruments.
For these applications, the appropriate docu-
ments (test reports, test and conformity certifi-
cates) must be noted. These are supplied with
the appropriate instrument.
Please note the attached approval documents
(yellow binder) and especially the attached
safety data sheet.
In Ex applications, the power must be pro-
vided only via an intrinsically safe circuit.
There are the following options:
- VEGAMET signal conditioning instrument in
Ex version
- non-certified VEGAMET signal conditioning
instrument with VEGA safety barrier type
145
- Ex separator (e.g. VEGATRENN 149 Ex)
- VEGADIS 371 indicating and power supply
unit in Ex version.
The legal documents of these instruments
must also be noted.
Application with power supply via Ex-
separator, e.g. VEGATRENN 149 Ex
The processing is done by an indicating in-
strument in non-Ex area.
Electrical connection