Danfoss is the first manufacturer to mass produce VFDs. The VLT AQUA drives increase efficiency and reduce installed cost by including features like end-of-curve protection, initial ramp-up and check valve ramp down, constant pressure (PID) control with a pressure transmitter, empty pipe fill mode, and a sleep mode that turns the pump off when usage is low but monitors pressure to wake up when needed. SmartStart technology makes this the easiest VFD to program and operate. Once programming is finished, the VLT AQUA drive will maintain constant pressure in the system. Danfoss NEMA 4X drives feature conformal coated circuit boards for protection in corrosive environments, can be installed near motors or other irrigation equipment (fertigation) without an additional protective enclosure. The optional 6-year DrivePro-Tection warranty includes coverage for lightning and electrical anomalies, which protects the user from loss during storms or other power quality issues.