OpenSprinkler Forums Hardware Questions V3.4 Max Power Supply Voltage

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  • #85138

    dancrocker
    Participant

    I’m looking at this product to replace my 20+ year old Hunter controller. The enclosure for this controller has a transformer that is connected to my house AC power and is labeled to output 25VAC. I measured it and it’s outputting 28.5VAC. The max power supply voltage of the open sprinkler controller is specified to be 28VAC. Would it be ok to reuse the transformer I have? It would be convenient to do so. I measured the voltage when none of the sprinklers were running so maybe the was part of the reason it was so high.

    #85144

    Ray
    Keymaster

    28.5VAC is ok. Technically the controller can withstand 30VAC at least. Also, AC transformers are not regulated, what you measured is the ‘no-load’ voltage. As soon as you connect it to a circuit or it starts to supply current, the voltage will drop rapidly towards its rated voltage (25VAC in your case).

    #85151

    dancrocker
    Participant

    Thanks!
    Yeah, this is what I figured. I’m a retired EE. I did ASIC and system design so my experience with power systems is limited, although I’m not entirely ignorant of them :). I thought that with sprinkler valve load(s) and the long wires to the valves, a higher no-load voltage would be normal and probably necessary.

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OpenSprinkler Forums Hardware Questions V3.4 Max Power Supply Voltage