The AC electric motor used for normal pumping operations and are generally the most economical motor choice. Electric motors that are designed for fixed-speed operation are often used. We may use other motors and pumps which are using another source of energy such as diesel or D C power.
The controller enables speed variation in the motor by varying the voltage which in turns changes the speed of the motor to the predetermined and programmed parameters. Most of these are ac-ac drive ac-ac and convert from ac input towards ac output inverter. The characteristics of ac motor require that the magnitude of the voltages inverter output towards adjustment of the motor so that it can match the load torque required.
The control panel consists of alphanumeric display, light indication and meters that provide information on operating the drive. Most of these are even provided with output and input terminals with connecting pushbuttons, as well as switches which includes other operating interface devices and control signals.
Pumps are centrifugal pumps normally used for water supply. In centrifugal pumps flow of water created not pressure. However, such pumps work at a fixed speed normal applications. If the same pump is driven with variable speed by Variable Frequency Drives (VFD) it will deliver water only at a desired flow requirement instead of a fixed flow. The VFD thus enables use of much lesser energy affecting great savings. The pump motor works only when water is required. The system is provided with a pressure sensor located at an unfavourable location which then sends signal to the control panel for starting and stopping the pump. A pressure tank of a small capacity is provided for protection of the system against water hammer. The tank also provides an appropriate cushion for the pressure switch.