Small drives play a big role in energy efficiency

Edited by the Engineeringtalk editorial team Jun 5, 2006

Variable speed drives and high efficiency motors ensure energy efficiency on large-scale capital projects, but huge savings can be made by applying the same methodology on a smaller scale.

Employing variable speed drives and high efficiency motors to ensure energy efficiency on a new large-scale capital project isn't difficult in principle.

Neither is finding the largest HVAC motor on an industrial site and fitting a drive to reduce the overall energy consumption, in order to meet a self imposed energy saving target.

Saving energy on a large scale therefore isn't rocket science: but one area that is equally as simple, but in many instances is being overlooked is small motors and small drives, often driving continuous process items such as fans, pumps and compressors.

The high number of smaller motors being used on any one site can often mean that the savings are comparable to that of applying a drive to one large fan motor for example, but the capital investment can be far lower.

The contribution to overall equipment efficiency (OEE) is also therefore higher.

"The idea that small drives can make a large contribution to energy saving is borne out by the figures", comments Justin Peters, Technical Manager at AC Tech Lenze and who has played a central role in developing a new simple-to-use Energy Saving Programme for customers.

"The recent increases in energy costs have contributed to the faster payoff times for small drives, the overall potential saving is huge and we believe it is currently being overlooked", continues Peters.

There are often just one or two very large motors on a production or processing site, whereas the majority of sites with any level of basic factory process or automation will include many smaller electric motors.

Just a few production lines can include hundreds of small motors and it is in these situations where the cumulative savings could be huge; almost two-thirds of industrial electricity consumption is due to the running of electric motors and drive systems.

The cost was recently estimated at over GBP 3 billion per annum, a large proportion of which is attributable to running fans, pumps and compressors.

The other attractive reasons for focusing on small drives for energy saving are the speed at which they can be installed and their simplicity of use.

The latest generation of low-cost Lenze smd AC drives for example are ready-to-run straight from the box with useful factory settings already in the memory chip for fan and pump applications and simple controls on the front of the drive for speed adjustment and basic programming.

The footprint of a 'submicro' drive is also so small now that it can often be fitted directly into the existing control panel on a machine and wired in with a minimum off fuss (the footprint of a 0.25kW Lenze smd drive for example is just 93mm wide by 83mm deep).

This ease of use means that the smd drive can be installed and working in a matter of minutes.

The result is that by focusing on small drives for energy saving the activity does not have to be a capital or labour intensive one, and can be implemented very quickly.

For a modest investment, many smaller motors from 0.25 to 22kW could be included in an energy efficiency improvement programme and provide cumulative savings that could reduce energy costs by thousands of pounds.