Max Current per Channel = 24V DC X 0.4A = 9.6W
1) If TX distance is 0 ft = what is the Current = (9.6W * 90%) / 12V = 0.72A
Note:
90% is the efficiency (since we are using High Efficiency component,
there is virtually no heat being generated) in another word our maximum
current output can reach above 0.7A.
2)
If TX distance is 300 ft, base on the characteristic of the power cable
and the resistant calculation @ 18 Ohms. First we have to find two
answers, one is the voltage drop and two is the Wattage consumed.
A: The drop in voltage from the cable is: 0.4A*18 = 7.2V, so the voltage arrived at the remote end will be: 24-7.2 = 16.8V.
B:
The Watt consumed: 7.2V * 0.4A=2.88W. The Wattage supplied at the end
is = 9.6W – 2.88W = 6.72W. After the step down conversion, the supplied
Wattage is = 6.72 * 90% = 6W.
So, the final output current is: 6W / 12V = 0.5A
Of course the quality of the UTP cable that you use will affect the voltage and power drop.
Door / Window Contact
