Honeywell Sensepoint XCL Installation Manual page 15

V+ detector
XCL V detector
V− detector
The maximum loop resistance (R
as follows:
R = (V
loop max controller
I = W
detector max detector max
Example
The controller is supplying a nominal 24 V DC (V
minimum allowable voltage of XCL is 11 V DC (V
the maximum allowable voltage drop across the cable between the
controller and detector is V
consumption of the detector is maximum 2.3 W (W
maximum current required to drive the XCL at the minimum voltage is
2.3 W ÷ 11 V DC = 209.1 mA (I
loop resistance (R
loop max
maximum cable length for any given cable type can be found by
dividing the maximum allowable cable resistance per core by the cable
resistance provided by the cable manufacturer.
The following table shows the typical maximum cable distances for our
example.
Cable size
(cross sectional areal)
2
0.5 mm (20 AWG )
2
1.0 mm (17 AWG )
2
1.5 mm (16 AWG )
2
2.0 mm (14 AWG )
2
2.5 mm (13 AWG )
nearest equivalent
Field Cable (L)
) in the field cable is calculated
loop max
− V ) ÷ I
detector min detector max
÷ V
detector min
− V
controller detector min
). So the maximum field cable
detector max
) is 13 V DC ÷ 0.2091 = 62 Ω. Therefore, the
Typical cable resistance
36.8 Ω/km
19.5 Ω/km
12.7 Ω/km
10.1 Ω/km
8.0 Ω/km
Installation
V+ controller
V controller Controller
V− controller
), and the
controller
). Therefore
detector min
= 13 V DC. Power
). The
detector max
Maximum cable length (L)
842 m
1589 m
2440 m
3069 m
3875 m
15