VEGA VEGALOG 571 - Manual (Page 36)

36 VEGALOG 571
Electrical connection
Connection instructions
The not-intrinsically safe input of the safety
barrier type 145 is connected via a standard
two-wire line to the EA-card.
The not-intrinsically safe input of the safety
barrier type 146 or VEGATRENN 546 is con-
nected via a standard two-wire line to the EV-
card.
If electromagnetic interferences are ex-
pected, screened cable should be used. The
screen must only be earthed on one sensor
or instrument side. The wiring of the intrinsi-
cally safe outputs of the safety barrier with
the sensors (in hazardous areas) must be
made acc. to the valid mounting regulations.
In addition the special conditions and instruc-
tions in the conformity certificates must be
observed.
Connection examples
Safety barrier type 145
VEGA
TRENN 546
on
VEGALOG
571 EV
!
Ex-area Not-Ex-area
VEGATRENN 546
VEGATRENN
547V␣ Ex EV-card
Ultrasonic
or
radar
on
VEGALOG
571 EV
!
11
+
12
-
+
1 -
2
ia-T
rennbarr
iere
T yp 145
Ausgang
Zone 0
Eingang
Ex-area Not-Ex-area
Pressure
transmitter
EA-card
Safety barrier
type 145
The sum of the inner capacitances and in-
ductances of all components must not ex-
ceed the max. permissible values of the
ia-IIC-circuit, see example:
Data of the ia-IIC-circuit:
L
ext
max. = 0,5 mH
C
ext
max. = 56 nF
Data of the components:
Component Pressure 1 overvoltage Line
Data transmitter arrester
L
int
0,1 mH 0,13 mH searched
C
int
0,3 nF 1 nF searched
Determination of the line data:
L
int
= 0,5 mH – 0,1 mH – 0,13 mH = 0,27 mH
C
int
= 56 nF – 0,3 nF – 1,0 nF = 54,7 nF
Calculation of the line length:
0,27 mH
I = ––––––––– • m = 415 m
0,65
µ
H*
54,7 nF
I = ––––––––– • m = 456 m
120 pF *
To be on the safe side, the line length in this
example must not exceed a value of 400␣ m.
* typical values for unscreened two-wire lines: L‘ =
0,65
µ
H/m; C‘ = 120 pF/m
VEGATRENN 546, VEGATRENN 547V Ex
The sum of the inner capacitances and in-
ductances of all components must not ex-
ceed the max. permissible values of the
ib-IIC-circuit, see example.