Wiring Instructions
62
SharpEye™
Single IR Flame Detector User Guide
B.2
Calculation Formula
Use the following formula to calculate minimum wire gauge per wire length
between the power supply (controller) and the detector, considering the number
of detectors on the same power line, where:
•
L = Actual wire length between the detector and the power supply
•
N = Number of detectors per loop
•
R = Resistance of wire per 100m (see Table 22)
•
V = Voltage drop on the wire
Calculate the voltage drop on the wire as follows:
V = 2L x R x N x 0.2A
100
•
20+V = Minimum required voltage of the power supply
•
0.2A is the maximum power consumption of the detector
For example, if N=1 (1 detector in loop)
•
L = 1000m
•
Wire size = 1.5mm² (see Table 23, the resistance per 100m for 1.5mm² is
1.4Ω)
Calculate the voltage drop in the wire as follows:
2 x 1000 x 1.4Ω
x 1 x 0.2A = 5.6V
100
The minimum voltage of the power supply should be 20V + 5.6V = 25.6V
