Page 155 - Gas Detection Systems Training Manual

VD = Voltage drop at far end of run
I = Current Draw Device X n (n=number of units) (One 3120 + Two Milleniums 0.585) (One 3100 + One Millenium 0.335)
R = r X d r = Ohms per 1000’ d = end to end cable length X 2 (multiply by 2 because 2 conductors +24VDC & DC Common
(I) Current Draw
Resistance
Voltage Drop
Returning to Power Supply
Device Current # of Devices
0.335 6
Wire AWG OHMs per 1000 feet
Total Current Draw AMPs
Dead End Distance Feet OHMS
600 1.2 Resistance
2.04
Total Voltage Drop Loop Back Power 2.0502
2.01
12 AWG 1.7 Total Current (I)
2.01
Dead End Voltage Drop 4.1004
X
÷ 2
Fill in the correct data in the Yellow boxes The calcualtions will automatically compute
VD = (I x R) / 2*
*Divide by 2 if load is distributed along run