Variable speed drive Fluid compression machines

In industrial installations, the compression, pumping and ventilation functions consume a significant proportion of the electrical energy used, accounting for around 45% of the overall electrical energy balance. It is therefore essential to seek ways of optimizing consumption in these areas.

The economic and technical benefits of using a variable-speed electric drive for the associated motors are numerous.

With this type of drive, the speed of the motor and the driven machine is not varied by influencing energy losses in the electrical supply circuit, in the motor or in the load. Instead, the electrical energy supplied to the motor is converted so that it provides the mechanical characteristics required by the process, with minimum losses. In addition to energy savings, this technique offers additional advantages that can be decisive when dimensioning a plant.

As far as the supply network is concerned, we can mention :

• eliminates high overcurrents in the current drawn by the AC motor when starting;

• reduced power to the power supply system.

As far as the motor is concerned, variable-speed drive technology extends its service life by reducing the stresses applied to it.

As far as the driven load is concerned, we can mention the possibility of adjusting torque and speed at any point in the force-velocity plane. This advantage derives from the flexibility, precision and rapidity of the system's controls.

Equipping a pump, fan or compressor with a continuously variable drive speed device is an ideal way of modifying the flow-pressure characteristics while maintaining good efficiency over virtually the entire operating range of the driven machine (pump, fan or compressor), since the performance of the energy conversion system's controllers enables optimum adaptation to the operating conditions imposed by the process.

Before describing all the advantages of variable-speed electric motive power generation for fluid-moving machine drives, we need to classify the different electrical solutions available for this type of installation.