VEGA VEGABAR 14 - Manual (Page 11)

5 Connecting to power supply
5 .1 Preparing the connection
A
lways keep in mind the following safety instructions:
l C onnect only in the complete absence of line voltage
l I f voltage surges are expected, install overvoltage arresters
Tip:
W
e recommend VEGA overvoltage arrester ÜSB 62-36G.X.
I n hazardous areas you must take note of the respective regulations,
conformity and type approval certificates of the sensors and power
supply units.
T he supply voltage and the current signal are carried on the same two-
wire connection cable.
P rovide a reliable separation between the supply circuit and the mains
circuits according to DIN VDE 0106 part 101.
VEGA power supply units VEGATRENN 149AEx, VEGASTAB 690,
VEGADIS 371 as well as all VEGAMETs meet this requirement. When
using one of these instruments, protection class III is ensured for
VEGABAR
14.
K eep in mind the following additional factors that influence the
operating voltage:
l O utput voltage of the power supply unit can be lower under
nominal load (with a sensor current of 20.5 mA or 22 mA in case of
fault message)
l I nfluence of additional instruments in the circuit (see load values in
chapter "Technical data")
T he instrument is connected with standard two-wire cable without
screen. If electromagnetic interference is expected which is above the
test values of EN 61326 for industrial areas, screened cable should be
used.
U se cable with round cross-section. A cable outer diameter of 5 … 9 mm
(0.2 … 0.35 in) ensures the seal effect of the cable gland. If you are
using cable with a different diameter or cross-section, exchange the
seal or use a suitable cable gland.
C onnect the cable screen on both ends to ground potential.
I f potential equalisation currents are expected, the connection on the
processing side must be made via a ceramic capacitor (e. g. 1 nF,
1500 V). T
he low frequency potential equalisation currents are thus
suppressed, but the protective effect against high frequency interfer-
ence signals remains.
Note safety instructions
Take note of sa-
fety instructions
for Ex applica-
tions
Select power supply
Select connection cable
Cable screening and
grounding
VEGABAR 14 11
5 C onnecting to power supply
22441
-
EN
-111006