Simtronics MultiFlame DF-TV7-T - Page 24

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ultiFlame DF-TV7 Page 24 / 56 NOSP16358-03 [04/2016]
4
wires
Version
A
0V
+24VDC
+24VD
Typ < 450
Ω
Detector
JP11
Fire or control system
Shielding to be
connected to the
enclosure
20 mA loop
+
-
+24VD
+
-
4.3.6. 4-wires connection (isolated power)
When using a 4 wires connection, the current loop is provided by the input module or PLC.
The loop (L + and L-) is optically isolated from the detector. 4-20mA or 0-22mA input module
of the PLC has to power up the current loop with, at least 8V at the terminal level, for 22 mA.
This reduces the resistance of the loop as defined in the relationship below.
mA22
V8tagesupply volPower
maxi R
−
=
In practice, the total loop resistance should not exceed 450 Ω with a voltage >18Vdc