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A small investment can prolong motor life and tackle EMI

16 March 2014

Tim Cooke describes how the simple expedient of installing a high current line reactor can help you make considerable energy savings, increase motor life and tackle any electromagnetic interference (EMI) issues.

REO's CNW903, three phase, high current line reactor

There is no doubt that we are living in an era of unprecedented change; in a world where competitiveness has captured the hearts and minds of those who hold the purse strings. From lean and Kaizen in manufacturing to third-tier auditing in supply chains and the push towards reducing carbon emissions using green technology, saving money is high on the agenda.

However, in some cases this rush to save money has come at the expense of taking the longer term view. Traditionally the most successful businesses have been those whose strategy has struck a good balance between short term efficiency and long term return on investment. 

Increased pressure to conform to legislative and corporate social responsibilities has further intensified the burden on companies to deliver high quality, on time and under budget.  For instance, the eco design directive covering electric motors, EC 640/2009, mandates that from January 1, 2015, all new motors must be equipped with a variable speed drive (VSD) by default.

In industrial applications a VSD is often used to control the speed of a motor. This increases efficiency and provides cost savings. However, the process is not completely without its drawbacks. In order to control the motor speed, the supply current is manipulated using pulse width modulation (PWM) for high frequency switching. 

The resultant fixed voltage, variable frequency supply output, whilst able to control motor speed, creates unwanted electromagnetic interference (EMI) and harmonic currents, whose high frequencies can damage equipment. Overheating of transformers, windings and capacitors as well as interference on telecommunications equipment and metering apparatus can render equipment unusable.

European legislation has sought to solve the problem through the introduction of the IEC/EN 61800-3 directive, which makes it obligatory for manufacturers, panel builders and systems integrators to ensure that all equipment is electromagnetically compatible with surrounding devices.

It is the combination of these factors which ultimately impact the triple bottom line; price, people and planet. Procurement and finance managers must make decisions which not only impact profitability but also the people and environment around them. Although ever decreasing budgets require intense scrutiny of any expense, some simple changes can result in significant savings.

Price is the first 'P' of the triple bottom line. To provide original equipment manufacturers (OEMs) with a simple way to reduce energy costs, REO has developed an EMC compliant input choke. The CNW903, three phase, high current line reactor removes harmonic currents and EMI from the power supply, reducing any voltage distortion, which could degrade or damage equipment. 

The unit’s small and efficient design has been achieved through careful selection of build materials and the application of design experience, which has resulted in a unit that requires much less panel space, and incorporates shielded terminals and protection covers.

In a typical example, a CNW903 choke, costing only a little more than fifty pounds, used on a 4kW VSD, achieved such significant energy savings, that return on investment was realised in less than five weeks - assuming an electricity cost of 11.2 pence/kWh and 50 hours usage per week. This amounts to over £900 of savings in the first year alone - rather significant, considering that the unit also increases motor life by reducing harmful harmonic currents.

People are the second 'P'. As anyone that works in an industrial environment will know, working conditions on the factory floor can be demanding. Ear noise and hand protection is the norm. The CNW903 is able to eliminate excess heat, acoustic noise and component vibration - including mechanical stress on machinery, by reducing the overheating of in phase neutral conductors. This means a quieter and cooler working environment for everyone in the environment.

Planet is the final 'P'. By reducing energy bills, companies can expect to meet and exceed not only government targets for carbon emissions, but also corporate social responsibility goals. Green credentials and brand awareness is also enhanced.

So why is it that, even though equipment such as the CNW903 exists, many companies are yet to realise these cost savings and improve their return on investment? The problem is one of procurement. 

A paradigm shift is required in the way that engineers pitch proposals to procurement teams. By pitching a holistic, triple bottom line return on investment, it can be shown that buying on price alone can be detrimental and in fact more costly in the long term. Only in this way, can an organisation hope to become truly competitive.

Tim Cooke is business development manager at REO UK


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