PRODUCT GUIDE - K-Rain

WIRE SIZING
RESISTANCE METHOD
Required Information
■ Actual one-way length of wire between the controllers
and at the power source of the controllers and valves
■ Allowable voltage loss along the wire circuit
■ Accumulative current flowing through the wire section
being sized in amperes
Resistance is calculated using formula:
R= 1000 x AVL
2L x I
R = Maximum Allowable Resistance
of wire in ohms per 1000 feet
AVL= Allowable voltage loss
L= Wire length (one way)
I= Inrush current
AVL for controller power wire sizing is calculated by
subtracting the minimum operating voltage required
by the controller from the minimum available voltage
at the power source.
TABLE 1
Resistance of Copper Wire
WIRE SIZE Resistance at 20° C (68° F)
AWG No. ohms per 1000 Feet
18 6.39
16 4.02
14 2.52
12 1.59
10 1.00
8 0.63
6 0.40
4 0.25
FORMULAS
AVL for valve wire sizing is calculated by subtracting
minimum solenoid operating voltage from controller
output voltage. This number will vary depending on the
manufacturer and in some cases with line pressure.
VALVE WIRE SIZING EXAMPLE:
Given: The distance from the controller to the valve is 1800 ft.
The controller output is 24V. The valve has a minimum operating
voltage of 20V and an inrush current of 370 mA (0.37Amps).
R = 1000 x 4
2(1800) x 0.37
R = 4000
1332
R = 3.00 ohms/1000 feet
Wire resistance can not exceed 3.00 ohms per 1000 feet.
Go to table #1 and select the proper wire size. Since 16
gauge wire has more resistance that 3.00 ohms per 1000
feet, choose 14 gauge wire.
Table 2 is a quick reference and is set up to provide maximum
wire runs given the information at the bottom of the table.
PRECIPITATION RATES (U.S.) (METRIC)
Equilateral Triangular P.R.= (GPM of 360) x 96.25 P.R.= m3/hr of 360 x 1000
Spacing (in/hr) (Head Spacing) 2 x .866 (mm/hr) m2 x .866
Square/Rectangular P.R.= (GPM of 360) x 96.25 P.R.= m3/hr of 360 x 1000
Spacing (in/hr) head Spacing x Row Spacing (mm/hr) Degrees of Arc x Head Spacing
Square/Rectangular P.R.= 3460 x GPM (for any arc) P.R.= m3/hr (for any arc) x 1000
Spacing for Specific Arc (in/hr) Degrees of Arc x Head Spacing x Row Spacing (mm/hr) Degrees of Arc x Head Spacing x Row Spacing
Horsepower H.P. = GPM x Ft of Head
3,960 x Pump Efficiency (expressed as a decimal)
TABLE 2
Valve Wire Sizing (Maximum One-Way Distance in Feet Between Controller and Valve)
GROUND
CONTROL WIRE
WIRE 18 16 14 12 10 8 6
18 850 1040 1210 1350 1460 1540 1590
16 1040 1340 1650 1920 2150 2330 2440
14 1210 1650 2150 2630 3080 3450 3700
12 1350 1920 2630 3390 4170 4880 5400
10 1460 2150 3080 4170 5400 6670 7690
8 1540 2330 3450 4880 6670 8700 10530
6 1590 2440 3700 5400 7690 10530 13330
Solenoid: 24VAC, Pressure: 150 PSI, Voltage Drop: 4V, Min. Operating Voltage: 20V, Amperage Peak: .37A
Station Run Time S.R.T. = Total Weekly Req’d (inch/wk) x 60 (min/hr) S.R.T.= Total Weekly Req’d (mm/wk) x 60 (min/hr)
(min/wk) Precipitation Rate (in/hr) (min/wk) Precipitation Rate (mm/hr)
ROTORS
SPRAY HEADS ELECTRIC VALVES CONTROLLERS INDEX VALVES / RCW CHARTS
Pipe Velocity V= 0.4085 x Flow (GPM) V= 1273.24 x Fl0flow (l/sec)
(ft/sec) (Inside Pipe Diameter in Inches) 2 (m/sec) (Inside Pipe Diameter in Millimeters) 2
Scheduling Coefficient S.C.= Average Precipitation Rate (in/hr) S.C.= Average Precipitation Rate (mm/hr)
Lowest PRecipitation Rate (in/hr)
Lowest Precipitation Rate (mm/hr)
Slope S= Rise (Measure of Length)
Run (Measure of Length)
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