Solenoid Valve Power

[John Carroll]

Two oil fired boiler oil valve solenoid valves,

One type, like mine has two windings, a pull in winding of 1.4ohm resistance which is supplied with 24VDC for a second or so, power, (24squared/1.4), 411W, the other, the hold in winding of 1400ohms is supplied continuously with 5VDC, power, (5squared/1400), 0.0178W.

 

The other type has one winding of 100ohms resistance which is supplied with 30VDC for a second or two, power, (30squared/100), 9W, 3VDC is then supplied continuously to the same winding, power, (3squared/100), 0.09W.

 

It seems  strange that less that one fifth of the hold in power, 0.0178W vs 0.09W is required for the two winding coil, the second coil requires 0.09/9, or 1% of the pull in power but even if 9W was sufficient pull in power for the two winding coil then the hold in power is still only, 0.0178/9, less than 0.2% of the required assumed 9W, seems extraordinarily low.