Simple demonstration reveals true energy savings using inverters

The demonstration rig in Hatfield consists of two identical blower motors side by side, used to drive fans to support mini footballs in vertical transparent tubes. One motor is operated direct on line (DOL) and so runs permanently at full speed. A manually operated valve is used to restrict the airflow in the tube, mimicking many mechanical damping systems, allowing the ball to change position.

The second motor is controlled by a Mitsubishi inverter drive, so its speed can be reduced to lower the ball. A Mitsubishi GOT series HMI touch screen is used to display and compare the power consumption of both motors.

In the video, which can be viewed at the Energy Saving Drives website. Mitsubishi's Matt Handley is seen working through the demo rig. It takes about three minutes to run the motors and get the readings. In the second half Matt runs through the theory to derive the Cube Law, then demonstrates the OEC (Optimal Excitation Control) function of the Mitsubishi drive for further energy savings.

Optimal Excitation Control is an innovation unique to Mitsubishi drives; based on advanced motor mapping algorithms it calculates and applies the optimum magnetic flux to the motor for its running conditions. This ensures maximum utilisation of the motor’s capacity at maximum efficiency and compliments other optimising functions such as autotuning and automatic slip compensation.

“We have also produced a virtual version of the display, which is hosted on-line at the Energy Saving Drives website," says Matt. "The idea of this is that potential installers of inverters can effectively run the demo themselves (and in their own premises) to fully explore the genuine potential of inverters. It is designed so that both technical and non-technical people can appreciate inverters’ energy saving potential.”