Power Cable Specification; Detector Module - Xtralis VESDA Sensepoint XCL Installation Manual

VESDA Sensepoint XCL – Large Bore Installation Manual
2.3 Power Cable Specification
VESDA Sensepoint XCL requires a power supply from the controller of specified supply voltage range in
section "1.7 Specifications". Ensure that a minimum supply voltage is measured at the VESDA Sensepoint
XCL, taking into account voltage drops due to cable resistance.
V+ detector
VESDA
V detector
Sensepoint
XCL
V- detector
The maximum loop resistance (R
R
loop max
I
detector max
Example:
The controller is supplying a nominal 24 V DC (V
Sensepoint XCL is 11 V DC (V
between the controller and the detector is V
Power consumption of the detector is maximum 2.3 W (W
the VESDA Sensepoint XCL at the minimum voltage is 2.3 W ÷ 11 V DC = 209.1 mA (I
maximum field cable loop resistance (R
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
2
1.0 mm
2
1.5 mm
2
2.0 mm
2
2.5 mm
2.4

Detector Module

1
Nearest equivalent.
8
Field Cable (L)
) in the field cable is calculated as follows:
loop max
= (V − V
controller detector min
= W ÷ V
detector max detector min
controller
). Therefore, the maximum allowable voltage drop across the cable
detector min
controller
) is 13 V DC ÷ 0.2091 = 62 Ω. Therefore, the maximum cable
loop max
Typical cable resistance Maximum cable length
1
(20 AWG ) 36.8 Ω/km
(17 AWG) 19.5 Ω/km
(16 AWG) 12.7 Ω/km
(14 AWG) 10.1 Ω/km
(13 AWG) 8.0 Ω/km
) ÷ I
detector max
), and the minimum allowable voltage of VESDA
− V = 13 V DC.
detector min
). The maximum current required to drive
detector max
(L)
842 m
1589 m
2440 m
3069 m
3875 m
Legend
V+ controller
V controller Controller
V- controller
). So the
detector max
1 Inhibit switch
2 Status indicator
3 UP button
4 DOWN button
5 Current sink/source
selection switch
6 Negative voltage output
7 Positive voltage output
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