09-2018
file: ISAFE3-OperationManual_EN_DE.R4.VEXH.docx
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Vallen ISAFE3 Operation Manual - Operation Manual
5
Signal Isolator SISO3
SISO3 is a so-called associated apparatus. That means it is an electrical apparatus which
contains both, intrinsically safe circuits and non-intrinsically safe circuits. It is constructed so that
the non-intrinsically safe circuits cannot adversely affect the intrinsically safe circuits (EN 60079-
0:2009 / 3.2). SISO3 is a module to be snapped on a DIN rail.
The purpose of signal isolator SISO3 is to
1.) electrically isolate the intrinsically safe sensor circuit from the AE system
2.) provide isolated DC-voltage for ISAS3 over the combined coaxial power/signal cable
3.) amplify the AE signal from the sensor and transfer it to the AE system
4.) transfer an AST control pulse from the AE system to the sensor
5.) limit the voltage, current, power and pulse energy on the intrinsically safe circuit in
accordance with EN 60079-11:2007 for use in zone 0, even in the case of two worst case
faults in SISO3 and two in ISAS3.
6.) ensure electro-
static discharge of intrinsically safe cable over 220 kΩ to earth at DIN rail,
when cable is interrupted.
Figure 5-1 SISO3 Module.
BNC: to AE system
SMA: Ex I to ISAS3 (Terminal
screw 4: left most screw)
Figure 5-2 SISO3-Block Diagram
CAUTION:
SISO3 must be installed within a dry and clean environment of pollution degree 2
or 1 (see EN 60079-11:2007 / F.2). For pollution degree see glossary. This needs
usually an enclosure of protection class IP54. See chapter 6 Accessories for
SISO3.
SISO3 does not contain an overvoltage protection for atmospheric electricity. It is
assumed that protection against atmospheric electricity is provided by other
means.
