There is no such animal. Voltage does not control speed. I know this for a fact. That is why the so called soft start is BS. Pump speed is controlled by Hz. A 60Hz pump runs at one speed 3600rpm. The pump either has enough voltage to run or it doesn't. For a 6060 that is 97V. Once started it will cut off below 82V. We test all these parameters to be sure they can run and restart in poor conditions and brown outs. The reason you cannot run a wavemaker is simple, the pump has to spin in only one direction, to do this we had to use a clutch mechanism. The same as if you shifted gears in your car every minute or so you would ruin your clutch, this is what happens to the pump. Once the clutch is gone the prop won't spin, when the prop doesn't spin the pump will overheat, if left long enough in this condition, the thermal protection switch will break and that is the end of the pump. The Electronic pumps have a sophisticated computer control system that enables speed control and because the computer controls rotation and tracks the orbit of the magnet, the computer itself can correct a backwards rotation so the brakes are rarely called upon- enabling a more rapid cycling.