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Food industry motor considerations

02 September 2018

Brian Bannister explains some of the main considerations when specifying motors for applications in food production environments. 

Electric motors are ubiquitous in food and beverage manufacturing plants, undertaking duties such as driving conveyor lines through to functions such as mixing, blending, chopping, weighing, coating, packaging and labelling.

However, in addition to specifying a motor that provides the required motive power other factors should also be taken into account. These include efficiency, hygiene and reliability to minimise downtime and maximise commercial benefit.

European directives are imposing increasingly higher motor efficiency requirements. Currently, for 3-phase applications between 0.75 and 375kW, the motors can be either IE2 when used with a variable speed drive (VSD) or a minimum of IE3 compliant if connected direct on-line only. However, if motor manufacturers or distributors held motors of lower efficiency in stock at the time the new energy efficiency requirements came into force then these motors are still acceptable.

Some motor companies are now also offering motors that meet the EU’s higher efficiency levels as defined in the IE4 and IE5 standards. While no date has been set for these to become obligatory they do serve to establish benchmarks and enable motor manufacturers to attribute recognised efficiency levels to their products.

An innovative approach to achieving these higher efficiency levels is the use of permanent magnet technology which can offer much more than greater energy efficiency and the resulting reduced running costs. They are also smaller and lighter than equivalent power rated standard motors.

A standard 5.5kW 112 frame IEC motor, for example, might weigh 34kg while a comparable hybrid 5.5kW motor comes in a 90 frame and weighs only 16kg. Again, a standard 7.5kW unit comes as a 132 frame and weighs 53kg while the alternative hybrid comes as a 112 frame and weighs just 26kg.

This means that machinery could be made lighter and/or more compact which, together with the energy saving, could contribute significantly to reducing the whole life-cycle cost.

Further, replacing an IEC standard motor with such an alternative could significantly up-rate the machinery’s performance. For example, by replacing a standard 132 frame 7.5kW motor with similar frame size hybrid permanent magnet alternative, with an output up to 30kW, equipment could benefit from an increase of power input of up to 400%, providing the system and application permit it.

For the maximum energy cost saving benefit from the higher efficiency, of these motors, they are best employed on continuously running operations.

Hygienic considerations
A big consideration when specifying any product for use in food production environments is hygiene. Consequently, stainless steel has a dominant presence in the manufacture of machines and equipment for this industry. To complement the use of stainless steel there are also stainless steel motors and gearboxes available. 

One breakfast cereal producer, for example, has saved over £4,000 in 12 months by swopping two ordinary motors for two stainless steel motors. This saving resulted purely from reducing maintenance engineering costs and does not include the savings arising from uninterrupted production.

Stainless-steel motors can be cleaned using commonly used cleaning liquids and when IP69/66K compliant they can be pressure washed in-situ on machines. Consequently, there is no need to remove these motors for cleaning avoiding lost production due to down time and avoid associated engineering costs. They also help to eliminate the dubious practice of ‘bagging’ critical motors prior to cleaning.

Stainless steel motors also eliminate any issue relating to rust and peeling paint which removes those risks relating to food contamination, particularly when sited above processing lines. 

In addition, helping to avoid contamination risk, the stainless-steel bodies are typically smooth bodied - with no cooling fins or other crevices that can harbour potential contaminants. In many instances, the motor name plate details are also etched directly onto the body to eliminate the usual name plate fixings and their potential contamination risks.

Brian Bannister is a motor specialist at Lafert Electric Motors.

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