VEGA D86_D87 Hydrostatic pressure transmitters - Manual (Page 17)

Pressure transmitters D86/D87 17
Electrical connection
3 Electrical connection
3.1 Connection instructions
The electronics in the pressure transmitter
requires a supply voltage of 12 … 32 V DC. It
is designed in two-wire technology, i.e. the
supply voltage and the digital output signal
are led via the same two-wire cable to the
terminals.
This external energy is provided via a sepa-
rate power supply unit, e.g.:
- power supply unit VEGASTAB 690
- processing unit with integrated DC voltage
source (e.g. active PLC input)
- VEGAMET, VEGALOG or VEGADIS 371
Make sure that the external energy source is
reliably separated from the mains circuits
acc. to DIN VDE 0106, part 101. The above-
mentioned VEGA devices meet this require-
ment and protection class III is therefore
guaranteed.
The external energy source must provide a
terminal voltage of at least 12 V on the trans-
mitter. The actual terminal voltage on the
transmitter depends on the following factors:
- output voltage U
H
of the external energy
source under nominal load.
- electrical resistance of the connected in-
struments in the circuit (see connected
instruments, load resistance).
Note the following instructions for electrical
connection:
- Connection must be made according to the
country-specific installation standards (e.g.
in Germany acc. to the VDE regulations).
- The terminal voltage must not exceed 36 V,
to avoid damage to the electronics.
- The electrical connection must have a pro-
tective measure against polarity reversal.
- Connection of Ex sensors only by qualified
personnel.
- The wiring between pressure transmitter
and power supply can be made with
standard two-wire cable.
- If strong electromagnetic interference is
expected, screened cable is recom-
mended. The screening must be done on
both ends. Note the installation regulations
for use in Ex areas.
- In case of overvoltages, we recommend
the use of pressure transmitters with inte-
grated overvoltage protection or the instal-
lation of VEGA overvoltage arresters.
- In the cable entry, a seal correctly fitting the
cable should be used.
Safety information for Ex applications
As a rule, do all connecting work in the com-
plete absence of line voltage. Always switch
off the power supply before you carry out
connecting work on the sensors. Protect
yourself and the instruments.
Qualified personnel
Instruments used in Ex areas must be in-
stalled only by qualified personnel. The quali-
fied personnel must observe and understand
the mounting regulations and the supplied
type approval certificates and conformity
certificates.
If an instrument is used in hazardous areas,
the respective regulations, conformity certifi-
cates and type approvals of the sensors,
separators or safety barriers must be noted
(e.g. DIN VDE 0165).