VEGA VEGAFLEX 52V - Manual (Page 18)

18 VEGAFLEX 51V and 52V
Electrical connection / Connection and connection cable
3 Electrical connection
3.1 Connection and connection
cable
Safety information
Ensure that the instrument is in currentless
condition. Always switch off the power sup-
ply before you carry out terminal work on the
radar sensors. Protect yourself and the in-
strument, especially when you use sensors
which do not work with low voltage.
Skilled staff
Instruments which are not operated with a
protective low voltage must only be con-
nected by skilled staff.
Connection
For connection a standard two or four-wire
cable (sensors with separate supply) with
max. 2,5 mm
2 can be used. Very often "Elec-
tromagnetic pollution" by electronic actuators,
energy lines and emitting systems is so
considerable that the two or four-wire cable
should be screened.
We recommend to use screened cable. This
screening prevents against future interfer-
ences (figure 3.1 a).
It is favourable to earth the screens on both
ends. However it must be noted that no earth
compensation currents flow via the sensor
cable screens (figure 3.1 b). Earth compen-
sation currents can be avoided by connect-
ing the cable screen in case of earthing on
both sides on one earthing side (e.g. in the
switching cabinet) via a capacitor (e.g.
0,1␣
µ
F; 250␣ V AC) to earth potential. Use a
very low impedance earth connection (foun-
dation, plate or mains earth).
In dust-Ex-applications the screen should be
on one end.
Ex-protection
If an instrument is used in dust-Ex areas, the
appropriate regulations as well as the dust-
Ex-certificate of VEGAFLEX for systems in
dust-Ex-areas should be noted.
Connection cable
Note that the connection cables must be speci-
fied for the expected operating conditions in
your systems. The cable must have an outer
diameter of 5␣ …␣ 9␣ mm (1/5 to 1/3␣ inch). Other-
wise 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 VEGAFLEX sensors the earth conductor
terminal is galvanically connected with the
metal thread.