VEGA VEGASON 54K…56K - Manual (Page 35)

VEGASON 54K … 56K 35
Electrical connection
5 Electrical connection
5.1 Connection and connection
cable
Safety information
As a rule, do the work in the complete ab-
sence of line voltage. Always switch off the
power supply before you carry out connect-
ing work on the ultrasonic sensors. Protect
yourself and the instruments, especially when
using sensors which do not operate with low
voltage.
Qualified personnel
Instruments which are not operated with
protective low voltage or DC voltage must
only be connected by qualified personnel.
Connection
A standard two or four-wire cable (sensors
with separate supply) with max. 2.5 mm
2 can
be used for connection. Very often the "elec-
tromagnetic pollution“ from electronic actua-
tors, energy cables and transmitting stations
is so considerable that the two-wire cable or
the four-wire cable should be shielded.
We recommend the use of a screened cable.
Screening is also a good preventative meas-
ure against future sources of interference.
However, you must make sure that no
ground potential currents flow through the
sensor cable shields. Ground potential cur-
rents can be avoided by potential equalisa-
tion cables. When grounding at both ends, it
is possible to connect the cable shield on one
side (e.g. in the switching cabinet) via an Y-
capacitor
1) to the ground potential. Use a low-
resistance ground connection (foundation,
plate or mains earth).
Note!
In Ex applications, grounding on both ends is
not allowed due to potential losses.
Ex protection
If an instrument is used in hazardous areas,
the respective regulations, conformity certifi-
cates and type approvals for systems in Ex
areas must be noted (e.g. DIN 0165).
Please note the approval documents with the
safety data sheet attached to the Ex sensors.
Connection cable
Please make sure that the connection cables
are specified for the expected operating tem-
peratures in your systems. The cable must have
an outer diameter of 5 … 9 mm or 3.6 … 8.6 mm,
to ensure the seal effect of the cable entry.
Protective conductor terminal
The electronics housing of the sensors has a
protective insulation. The protective conduc-
tor terminal and the earth terminal in the elec-
tronics housing are galvanically connected
with the metallic transducer diaphragm.
On sensors in version B, the protective con-
ductor terminal is galvanically connected to
the transducer diaphragm via the transducer
tube when the sensor is completely mounted.
On version C and D, the connection is made
via the cable screen of the transducer cable
and the transducer tube.
1) max. 10 nF, e.g. voltage resistance 1500 V, ce-
ramic