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6. Pressure Monitors in Intrinsically Safe Circuits (Ex-i)
6. Pressure Monitors in
Intrinsically Safe Circuits (Ex-i)
according to ch. 5.7 of EN 60079-
11:2012, "Simple electrical apparatus"
10 k
10 k
10 k
1
3
1
3
1
ZF574
ZF575
ZF576
Fig. 14. Wiring diagram
The pressure monitors correspond in all
technical data to the aforementioned
model series. In addition, a resistor-
combination is included in the switching
device, which, together with a suitable
Ex-proof switching amplifier, monitors the
wires between the isolating amplifier and
the pressure monitor for cable break and
short circuit. In case of cable break or
short circuit, the system switches off
towards the safe side. According to its
approval, the switching amplifier must be
installed outside of the Ex-zone.
Wiring of switching amplifier only accord-
MU2B-0264GE51 R0220G
ing to its mounting and wiring instructions
and valid standards and guidelines for
intrinsically safe circuitry.
Voltage rating
U
14 VDC R
i
L
100 µH
C
i
10 k
3
1
3
ZF577
Type of Ex-protection
Gas:
II 1/2G Ex ia IIC T6 Ga/Gb
Dust:
II 1/2D Ex ia IIIC T80°C Da/Db
CAUTION:
Never operate pressure monitors
with resistor combinations without
suitable switching amplifier.
Device can overheat and burn
due to overload of resistor
combination.
Approvals
ATEX: IBExU12ATEX1040
IECEx: IECEx IBE 14.0077
1.5 kOhm
i
1 nF
i
59
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