E5-PA series is a new constant pressure water supply inverter launched by V&T. E5-PA inverter, combined with the multi-pump control expansion card, can realize the multi-pump constant pressure water supply in turn with circulating; Built-in PID control--the current water pressure is detected by the pressure sensor, and according to the change of water pressure, 4 pumps are automatically switched to water supply at constant pressure under same power; At the same time, it can realize overpressure alarm, underpressure alarm, multi-time water supply at constant pressure, water supply at pressure constant with designated pressure and designated date, sleep control, change pump on time etc.