automation4me - Drive Tech

A common configuration , typically found in filtration plants , uses two pumps, one of which is in operation and the other is on standby , as shown in fig. The pump motors were originally driven thru’ star delta starters. The flow required at the output was being controlled as desired by throttling the output discharge valve.

By reducing the speed of the pump instead of throttling the discharge valve one could save energy.This can be achieved in two phases i.e. with the A.C drive in open loop and in closed loop with PID control using output pressure as the controlled parameter.

An energy meter and hour meter can be used to record the consumed power and time , in all three situations , viz.

1. Without AC drive
2. With AC drive , in open loop
3. With AC drive , in closed loop

40 – 50 % savings can be recorded by usage of AC drive with associated benefits like :

Precise control of pressure and flow rate with the help of inbuilt PID control.

Reduced wastage of water.

Enhanced life of mechanical seals on equipment downstream to the pump due to pressure control.

L&T Automation has significant achievements to its credit on this application with Yaskawa inverters.