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‘Low voltage drives only became economically viable relatively recently’

Andrew Bould, UK food & beverage industry manager for drives at ABB, asks why one of the best-kept secrets for driving down bakery energy costs is not more widely implemented.

There is a strong appetite in the baking industry to find ways to improve energy efficiency and reduce bills. Often the go-to tactic is to shop around for a cheaper supplier, but this might only make a small, short-term dent. However, there is another approach that could help dramatically reduce energy costs.

Few pieces of equipment are as ubiquitous throughout a modern bakery plant as the electric motor. They are used to control processes at almost every stage, from dosing pumps, mixers and extruders, to oven fans, chiller compressors and conveyor belts.

Different applications will require different motor speeds. If slower speeds are required, this would traditionally be achieved by throttling the motor output using valves, dampers or vanes.

However, in such an arrangement, the motor is still running at full power. This is like trying to drive a car by putting your foot to the floor on the accelerator, while simultaneously using the brake to try and control your speed. Clearly no one drives like this as it would waste huge amounts of energy and rapidly wear out equipment. Nevertheless, it’s estimated that over 90% of all industrial motors are run without any form of speed control, which equates to vast amounts of wasted energy.

A variable speed drive (VSD) is a device that can almost completely eliminate that wastage. It electronically controls the motor, so that it only uses the energy it needs to achieve the required level of output at any given time. This, alone, can have a significant effect on energy usage, but with variable torque applications like centrifugal fans and pumps, the savings are even higher.

So why have drives not been more universally adopted? One explanation is that low voltage drive technology only became economically viable relatively recently in the 1980s and ’90s, so there is still a lack of awareness about its benefits. Also, there is the upfront cost of additional equipment, but this is typically dwarfed by the savings over a drive’s lifecycle, with payback times of as little as six months.

VSDs are not a magic bullet for all applications. For fixed speed processes, the savings will not be as extreme, although VSDs still have plenty of other features to improve any motor’s efficiency, safety and reliability.

In short, if the baking industry is to take reducing its carbon footprint seriously and lower its energy usage, investing in variable speed drives is a quick and cost-effective way of doing so.