Connecting To Power Supply; Preparing The Connection - Vega VEGABAR 82 Operating Instructions Manual

5 Connecting to power supply

Safety instructions
Voltage supply
Connection cable
Cable screening and
grounding
22
5 Connecting to power supply
5.1

Preparing the connection

Always keep in mind the following safety instructions:
•
Carry out electrical connection by trained, qualified personnel
authorised by the plant operator
•
If overvoltage surges are expected, overvoltage arresters should
be installed
Warning:
Only connect or disconnect in de-energized state.
Power supply and current signal are carried on the same two-wire
cable. The operating voltage can differ depending on the instrument
version.
The data for power supply are specified in chapter " Technical data".
Provide a reliable separation between the supply circuit and the
mains circuits according to DIN EN 61140 VDE 0140-1.
Power the instrument via an energy-limited circuit acc. to IEC 61010-
1, e.g. via Class 2 power supply unit.
Keep in mind the following additional factors that influence the operat-
ing voltage:
•
Lower output voltage of the power supply unit under nominal load
(e.g. with a sensor current of 20.5 mA or 22 mA in case of fault
signal)
•
Influence of additional instruments in the circuit (see load values in
chapter " Technical data")
The instrument is connected with standard two-wire cable without
shielding. If electromagnetic interference is expected which is above
the test values of EN 61326-1 for industrial areas, shielded cable
should be used.
Use cable with round cross section for instruments with housing and
cable gland. Use a cable gland suitable for the cable diameter to
ensure the seal effect of the cable gland (IP protection rating).
If shielded cable is required, we recommend connecting the cable
screening on both ends to ground potential. In the sensor, the cable
screening is connected directly to the internal ground terminal. The
ground terminal on the outside of the housing must be connected to
the ground potential (low impedance).
In Ex systems, the grounding is carried out according to the installa-
tion regulations.
In electroplating plants as well as plants for cathodic corrosion protec-
tion it must be taken into account that significant potential differences
exist. This can lead to unacceptably high currents in the cable screen
if it is grounded at both ends.
VEGABAR 82 • 4 ... 20 mA