Input Mode Active/Passive; Connection Procedure; Wiring Plan - VEGA VEGAMET 381 Ex Betriebsanleitung

5 Connecting to power supply
5.2

Input mode active/passive

On the rear of the instrument you can find a
cover which can be opened with a screwdriver.
Subjacent there is a slide switch by means of
which you can switch over between active and
passive mode of the measuring data input.
•
In active mode, VEGAMET 381 Ex provides
the power for the connected sensors. Power
and measurement data are transmitted
over the same two-wire cable. This mode
is provided for connection of measuring
transducers without separate power supply
(sensors in two-wire version).
•
In passive mode the sensors are not powe-
red, only the measured value is transmitted.
This input is for connection of transmitters
with their own separate voltage supply (sen-
sors in four-wire version). The VEGAMET
381 Ex can also be looped into the existing
circuit like a normal ammeter.
The position of the slide switch also
influences the preconditions for Ex
implementation. Take note of the type
approval certificate or the conformity
certificate ofVEGAMET 381 Ex.
5.3

Connection procedure

Proceed as follows:
1. Mount VEGAMET 381 Ex
2. Connect sensor cable to terminal 1 and 2,
and where applicable, connect the screen
3. Connect power supply (switched off) to
terminal 5 and 6
4. If necessary, connect fail safe and operating
relay as well as current output
The electrical connection is finished.
After connection, it is absolutely ne-
cessary to plug the blue Ex separating
chamber to terminals 1 and 2 (sensor
input). This ensures the required dis-
tance of at least 50 mm (1.97 in) to other
instruments.
1. Place the Ex separating chamber as shown
below on the terminals of the sensor input
2. Lead the sensor cable towards the front and
out of the Ex separating chamber
3. Push the Ex separating chamber towards
the front until you hear it snap in
26
5.4

Wiring plan

Overview
1
7
Abb. 15: Wiring plan with two-wire sensor
1 Measurement data input, optionally available with
sensor power supply
2 Current output
3 Fail safe relay
4 Relay 2
5 Relay 1
6 Voltage supply
Tip:
For parameter adjustment of connec-
ted HART sensors, the sockets are
integrated in the terminals of the meas.
data input. A VEGACONNECT can be
directly plugged in without the need of
an additional HART resistor.
VEGAMET 381 Ex • 4 ... 20 mA signal conditioning instrument
+ - + -
2
1 2 3 4
1 2
1
2
on
%
18 17 16 15 14 13 12 11 10 9 8 7 6 5
N- L1+
3 4 5 6