Lift Station with VFD's
DFS' TCU pump-controller can also be used for level control at VFD Lift Stations. The TCU is outfitted with the RIO-032 I/O expansion device to provide the additional analog points needed for speed control and speed status.
In this application, the TCU with RIO-032 package was designed to operate a lift station with three VFD's. Each VFD is monitored and controlled locally at the TCU pump controller. The VFD's can be automatically controlled, manually controlled, or turned off using the HAND-OFF-AUTO (HOA) selector switches on the TCU.
Well level is provided by a (4-20 ma) submersible level transducer. A high float and low float are utilized for back-up purposes. Using the TCU's operator interface, an operator can readily select and adjust all start/stop operating parameters and level control set-points.
When in HAND, the speed of a drive is manually varied by the operator via INCREASE / DECREASE buttons on the TCU. In the AUTO mode, the TCU controls the drives in a pre-programmed Lead/Lag mode.
The Lead VFD is designated by the TCU, while the other two VFDs function in Lag / Lag2 as required for the level control operation. The designated Lead VFD alternates between each pumping cycle. In the AUTO mode, when multiple drives are required, each drive equally shares the load.
This is just one example of a VFD application using the TCU pump controller. DFS can work with you or your engineer to develop an operation scheme that meets your specific requirement.