Vega VEGAMET 381 Ex, Руководство по эксплуатации

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5 C onnecting to voltage supply
5 . 1 P reparing the connection
G enerally not the following safety instructions :
l
C onnect only in the complete absence of line voltage
l
I f overvoltage surges are expected , overvoltage arresters
should be installed
T ip :
W e recommend VEGA overvoltage arresters B 61 - 300 ( power
supply VEGAMET 381 E x ) and B 62 - 36 G ( sensor supply ).
I n hazardous areas you should take note of the appropriate
regulations , conformity and type approval certi fi cates of the
sensors and power supply units .
T he power supply can be 20 … 253 V AC , 50 / 60 H z or
20 … 253 V DC .
P ower supply of VEGAMET 381 E x is connected with standard
cable according to the national installation standards .
S tandard two - wire cable without screening can be used to
connect sensors . I f electromagnetic interference is expected ,
screened cable must be used .
C onnect the cable screen on both ends to ground potential . I n
the sensor , the screen must be connected directly to the
internal ground terminal . T he ground terminal outside on the
sensor housing must be connected to the potential equal -
isation .
I f potential equalisation currents are expected , the screen
connection on the side of VEGAMET 381 E x must be made via
a ceramic capacitor ( e . g . 1 n F , 1500 V ). T he low frequency
potential equalisation currents are thus suppressed , but the
protective e ff ect against high frequency interference signals
remains .
T ake note of the corresponding installation regulations for E x
applications . I n particular , make sure that no potential equal -
isation currents fl ow over the cable screen . I n case of
grounding on both sides this can be achieved by the use of a
capacitor or a separate potential equalisation .
N ote safety instructions
T ake note of safety
instructions for E x
applications
S elect power supply
S electing connection cable
C able screening and ground -
ing
S elect connection
cable for E x applica -
tions
VEGAMET 381 E x - 4 … 20 m A signal conditioning instrument 11
C onnecting to voltage supply
30418
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EN
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060925