The controller is for the "3 wire pumps and includes capacitors to boost the starting voltage. With the higher voltage you need far less amps.
I don't know the correct numbers, for a simple example, say a pump with a total distance of 600 feet of wiring needs 5 amps to run under a full load, that only requires 14 gauge wire. When starting, it may draw 15 amps, which would require at least 10 gauge wire. 14 gauge wire on a 600' run would probably burn up the motor from low voltage or melt the wire on start-ups. Adding the controller, you only need heavy wiring between the power supply and the controller, because the controller will release the stored high voltage power in the capacitors on each startup and draw the full 15 amps from the power supply, but after the start-up, only the 5 amps is needed.
Clear as mud now?
