VEGA VEGABAR 21 - Manual (Page 13)

VEGABAR 21 13
Mounting, electrical connection
2 Mounting
VEGABAR can be mounted in any position.
The cable entries have to point downwards to
avoid humidity ingress. For this purpose the
housing can be rotated by 330° against the
mounting part.
For mounting, a seal must be used corre-
sponding to the connection. This seal is either
supplied with VEGABAR or must be provided
by the customer.
Compensation of the atmospheric
pressure
The atmospheric pressure of instruments
used for overpressure measurements is
compensated via a breather facility inte-
grated in the housing.
3 Electrical connection
3.1 Connection information
The electronics in VEGABAR 21 requires a
power supply of 12 … 36 V DC. It is pro-
vided in two-wire technology, i.e. supply
voltage and current signal are led to the
terminals via the same two-wire connection
cable.
This external energy is provided via a sepa-
rate power supply unit:
- power supply unit, e.g. VEGASTAB 690
- processing unit with integral DC-current
source (e.g. active DCS-input)
- VEGAMET or VEGADIS 371
Observe that the external energy source is
reliably separated from the mains circuits
acc. to DIN VDE 0106, part 101. The above
mentioned VEGA-instruments meet this re-
quirement and protection class III is therefore
ensured.
The external energy source must supply a
terminal voltage of at least 12 V to the trans-
mitter. The actual terminal voltage on the
transmitter depends on the following factors:
- output voltage of the external energy
source under nominal load.
- Electrical resistors of the connected instru-
ments in the circuit (see connected instru-
ments, load resistor).
Note the following instructions for electrical
connection:
- The connection must be made acc. to the
specific installation standards (e.g. in Ger-
many according to the VDE-regulations).
- The terminal voltage must not exceed 36 V
to avoid damage of the electronics.
- The electrical connection is provided with a
reverse polarity protection.
- The wiring between VEGABAR and power
supply can be made with standard two-
wire cable.