I'm confused by the use of the Min Max settings.

Documentation States : "Redstone is emitted when the power level is above the minimum and below the maximum."

I don't understand how you use the minimum ? If I set the minimum at anything other than 0% and the power falls below that level, the redstone will turn off ? How would I use that?

I was expecting the function to be when the power level falls below the minimum, redstone turns on. Then redstone turns off when the power level exceeds the maximum.

So when a power source falls below 40%, power generation is turned on and allowed to run, until the power source reaches at least 90% then stops. Drop to 40, charge back up to 90.

Direwolf20 1.18
RfToolsPower 4.0.5

The minimum and maximum give the range where the redstone will turn on. i.e. if power >= minimum and power <= maximum the power will turn on

You can set minimum to 0 if you want it to be on all the time if power is below the maximum