VEGA VEGAPULS 51V…54V - Manual (Page 41)

VEGAPULS 51 V … 54 V 41
Electrical connection
5 Electrical connection
5.1 Connection and connection
cable
Safety information
Ensure that the instrument is unpressurized
before you start work. Always switch off the
power supply before you carry out clamping
work on the radar sensors. Protect yourself
and the instruments. Especially when you
use sensors which do not work with low
voltage.
Skilled staff
Instruments operated in Ex-areas must only
be connected by skilled staff. This staff must
note the installation regulations and the
attached type approvals and conformity
certificates.
Connection
A standard two-wire cable with max. 2,5 mm 2
can be used for connection. Very often
"Electromagnetic pollution" by electronic
actuators, energy lines and transmitting
stations is so considerable that the two-wire
line must be screened.
We recommend to use a screening. This
screening prevents against future
interferences. It is useful to earth the cable
screens on both ends, however it must be
noted that no earth compensation currents
flow via the sensor cable screens. You avoid
earth compensation currents by connecting
the cable screen on one earth side (e.g. in
the switching cabinet) via a capacitor (e.g.
1 µF; 100 V) with earth potential in case of
earthing on two ends. Use a very low
impedance earth connection (foundation,
plate or mains earth).
Ex-protection
If an instrument is used in hazardous areas
the appropriate regulations, conformity
certificates and type approvals for sensors
and separators or safety barriers must be
noted (e.g. DIN VDE 0165).
Sensors used in Ex-area must only be
operated on intrinsically safe circuits. The
permissible electrical values are stated in the
conformity certificate or the type approval.
Connection cable
Note that the connection cables must be specified
for the expected operating temperatures in your
systems. The cable must have an outer diameter
of 5 … 9 mm. Otherwise the seal effect of the
cable entry will not be ensured.
Cables for intrinsically safe circuits must be
marked blue and must not be used for other
circuits.
Earth conductor terminal
On VEGAPULS 51/52 sensors with a 1 1 /
2
"
thread of plastic, the earth conductor terminal
is galvanically isolated.
On all VEGAPULS 53/54 sensors as well as
VEGAPULS 51/52 sensors with metal thread,
the earth conductor terminal is galvanically
connected with the metal process
connection.