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5 Connecting to power supply
VEGAPULS 11 • Two-wire 4 … 20 mA
58350-EN-221027
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
Warning:
Only connect or disconnect in de-energized state.
The data for power supply are specified in chapter "
Technical data
".
Note:
Power the instrument via an energy-limited circuit (power max. 100 W)
acc. to IEC 61010-1, e.g.
•
Class 2 power supply unit (acc. to UL1310)
•
SELV power supply unit (safety extra-low voltage) with suitable
internal or external limitation of the output current
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
")
Use cable with round cross section for instruments with housing and
cable gland. To ensure the seal effect of the cable gland (IP protection
rating), find out which cable outer diameter the cable gland is suitable
for.
The instrument is connected with standard two-wire cable.
If electromagnetic interference is expected which is above the test
values of EN 61326-1 for industrial areas, shielded cable should be
used.
Note:
If the temperatures are too high, the cable insulation can be dam-
aged. Hence keep apart from the ambient temperature also the self-
heating of the instrument for the temperature resistance of the cable
in the connection compartment in mind.
1)
We recommend to connect the cable screening to ground potential at
one end on the supply side when using shielded cable.
Metric threads
In the case of instrument housings with metric thread, the cable gland
is screwed in at the factory. It is sealed with plastic plugs as transport
protection.
Safety instructions
Voltage supply
Connection cable
Cable screening and
grounding
Cable gland
2)
With an ambient temperature ≥ 50 °C (122 °F) the connection cable should
be suitable for a temperature which is at least 20 °C (36 °F) higher.
