Energy Efficiency

Energy and maintenance expenses for a typical pumping system can add up to be more than 65% of the total life cycle cost. Therefore, energy efficiency is a critical factor when investing in new equipment or simply retrofitting existing control systems. With the ECO SMART STATION™ control system, up to 30% energy savings is achievable.

How Does the Energy Savings Work?

The Affinity Laws define the relationship between pump speed (n) and power (P), where P2 = P1 (n2 / n1)3

Motor speed (n) in RPM can be controlled with the use of Variable Frequency Drives (VFDs), where n = (120 x Hz)/Poles

The graph shown here illustrates how a small reduction in pump speed will result in considerable energy savings.

The EnergyView™ Controller with the kW Logix™ Software uses an "Efficiency Auto-Tune" algorithm that searches for the pump speed (Hz) that will consume the least amount of energy per gallons of liquid pumped (W/GPM). The flow (GPM) is calculated from the level changes, tank dimensions, fill and discharge times. A flow meter is not needed. The pump motor power (W) is monitored by the VFDs and transmitted to the controller. No power meters are required.

The auto-tune program also takes into account the reduction in flow and head characteristics of the pump resulting from speed reductions to determine the Best Efficiency Frequency (BEF).

When the Best Efficiency Frequency (BEF) is found, the pumps will operate at this speed during every cycle. This mode of operation (ECO mode) is very efficient during low and normal in-flow to the station.

Cycle Operation or Constant Level Operation?

During high in-flow operation (peak hours), it is more efficient to operate in proportional-integral-derivative control mode (PID mode) than cycling the pump ON and OFF. kW Logix™ Software recognizes high in-flow conditions and automatically switches the operation mode from ECO mode to PID mode. During PID operation the pump speed is controlled to match the incoming flow and maintain a constant wet well level. When the in-flow returns to normal, the operation returns to cycle based (ECO mode) of operation automatically.