Smartmulti > Food & Beverage
What is a Variable Speed Drive?
A variable speed drive (VSD), speed-controller or frequency-controlled, compressor automatically adjusts its motor speed to the air demand. Its counterpart, fixed speed or “idling compressor”, or “load/unload compressor, is either on full throttle or off. Compare it to a car: an “idling compressor” either drives 100 km per hour or not at all. That is fine if the application requires an either full load or no load compressed air supply. But most applications don’t, they have a fluctuating air demand and that is where a VSD compressor comes in the picture. A Variable Speed Drive compressor simply adjusts its motor and elements speed to match the demand.
Boosting productivity in a process means different things to different people within manufacturing plants. Some goals include: − enhance the quality of the end-product − increase the throughput of production − reduce the electricity consumed by the process, while at the same time meeting carbon dioxide emission limits that may be required − maximise the process up-time, while at the same time minimising the costs associated with maintenance. And while achieving all these things, the end user can ill afford to take their eye of the current legislation, regulations and directives. The one simple product that can have an impact on all these productivity goals is the variable speed drive (VSD). Throughout the food and beverage sector some 63 percent of all electricity consumed is by electric motors.
Energy saving – Given that power consumption savings of 50 percent can be made by reducing the motor speed by just 20 percent, and with payback times as short as six months, VSDs are arguably the one product that can have the maximum impact on a company’s energy and carbon reduction policy.
Enhancing quality – A VSD enables a process to achieve fast and accurate speed or torque control while maintaining the repeatability demanded by the production line. This optimal process control leads to a more consistent quality end-product, which means the best profit for the customer. For example, some VSDs feature application macros, which are routines dedicated to say, pumps, conveyors or other uses. A pump macro can maintain product consistency by telling the drive to start additional pumps in response to a pressure drop, should there be a surge in demand. In addition to dedicated pump control, the VSD provides a pre-pressurization for process start-ups.