Selecting Power Conditioning Transformers:

In order to select the proper size transformer, it is necessary to know:

1. The operating voltage of the controllers, computers, and other items that will be connected to the output of the transformer.
2. The current draw of each controller, computer, etc.

Once this information is available, the following formula is used to determine the size of the transformer. Separate volt-ampere (VA) requirement calculations are needed for transformers at each power source.

Transformer Size = (controller requirement + valve requirement) X 1.3

Note that the transformer cannot be operated at 100% of capacity. The 1.3 figure in the above formula gives an appropriate safety factor.

Example:

On a golf course with a single power source, the following information is collected:

1. There are 18 controllers being supplied by the transformer. The controller operating voltage is 105-120 VAC. This means we operate the transformer at its output of 120 VAC.
2. From the controller manufacturer’s catalog, we find that each controller has a current draw of 0.19 amperes (no load). "No load" means without any valves activated.

Controllers Requirement = Volts X Amps X Number of controllers

Controllers Requirement =120 X 0.19 X 18 = 410.4 VA

From the design it is determined that the worst case hydraulic condition will be when 3 valves per controller are running, or a total of 54 valves (3 valves per controller X 18 controllers.)

From the valve manufacturer catalog, we learn that the valves operate at 24 VAC and draw 0.20 amps (holding) current. Each valve needs 4.8 VA (24Volts X 0.20Amps.)

Valves Requirement = 4.8 VA X 54 valves = 259.2 VA

Using the above formula:

Transformer Size = (controller requirement + valve requirement) X 1.3

Transformer Size = (410.4 + 259.2) X 1.3 = 669.6 X 1.3 = 870.48 VA

Now you can select the transformer from the chart below. It must be the next larger size closest to 870.48 VA. In this case, it would be the 1,000 VA model.

These transformers are noisy and they are at times installed outdoors. For outdoor installations, the transformers must be within a NEMA-3 enclosure with a minimum BTU rating per below chart and of sufficient size to allow wiring access.

Paige Part No.	SOLA Part No.	Voltage		Output Capacity (Volt-Amperes)	BTU Output
		Output	Input
250000	63-23-112-4	120	120, 208, 240	120	136
250010	63-23-125-4	120	120, 208, 240	250	225
250020	63-23-150-8	120, 208, 240	120, 208, 240	500	280
250030	63-23-175-8	120, 208, 240	120, 208, 240	750	444
250040	63-23-210-8	120, 208, 240	120, 208, 240	1000	519
250050	63-23-215-8	120, 208, 240	120, 208, 240	1500	686
250060	63-23-220-8	120, 208, 240	120, 208, 240	2000	1,229
250070	63-23-230-8	120, 208, 240	120, 208, 240	3000	1,331
250080	63-23-250-8	120, 208, 240	120, 208, 240	5000	2,117

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