Soils 456 Irrigation and Drainage Answers to chapter 11 questions

1 Electrical vlavle in-frush current 0.6 A. Voltage 21. Out put voltage of controller 26V ,. 18 conductor wire.
Distance of wire calculation a)26V-21V= 5V, B)R= 5V/0.6 A= 8.33 ohms. C. wire 6.78 ohms/1000ft , 8.33/6.78*1000= 1224 ft divided by 2 = 612 ft distance from controller

2. Elelctric Valve in-rush curent 0.5 A located 1000ft from controller providing 24 V. One conductor 18 wire other conductor 14 wire. Voltage to operate valve.
Total resistance 6.78 ohms + 2.68ohms= 9.46ohms . V= 9.46ohms*0.5 A= 4.72 volts. 24V-4.72V= 19.27 V

3. Electric Valve in-rush current of 0.4 A. 2000ft away from controller. Minimum size to have no more than 2 V drop.
2V= 0.4 R, R= 5 ohms total resistance= 5ohms/4000ft= 1.25 ohms/1000 ft= number 10 wire

4. Two valves operated same controller station 2000ft away. In-rust current 0.2A and 0.3 A . Voltage drop 3 V.

I= 0.5 A

V= IR= 3V=0.5A*R , R= 6 ohms/4000ft= 1.5 ohms/1000ft= number 10 wire.