Shield Shiel A-XT - Page 91

Calculations B
Shield Fire, Safety and Security Ltd.
Shield A-XT Releasing Fire Control Panel - Installation and Operation Manual SEXTCP-OM
Revision E01.00
82 of 127
The figure below illustrates an example circuit for determining maximum wire length where values are provided for
minimum operating-voltage of the NAC channel output (Vopmin), maximum current of the circuit (Imax),
wire-resistance-per-foot of the circuit (Rwire) and maximum current-draw of the strobe (Istrobe):
Figure B-1
Example Circuit For Determining Maximum Wire Length
NAC2NAC1
Fire In Zon
Supervised EOL
Resistor, 10K
SEOLR-10
EOL Resistor
10K
SEOLR-10
Vop
min
L
max
= 548 FT
+
++
+
.209 A
I
strobe
.209 A
I
strobe
.209 A
I
strobe
-
+
-
+
-
+
-
+
Example circuit identifies wire
length for two conductor cable
V
outmin
measured across
NAC1 terminals