By replacing all direct-on-line AC motors in the world with frequency converters, the energy saving consumption of AC motors would be approximately 30 per cent. This is appr. 10 per cent of the total consumption of electrical energy, globally.

In recent years, energy saving aspects has got - for economical and egological reasons - lots of attention from industrial field.

During year 2011, many projects, e.g. in the field of metal, paper, energy and mining industry in Finland, has been implemented with energy efficient motors and frequency converters. One target of these projects was energy savings. Energy saving trend will continue during year 2012 and in the future, thanks to high energy costs.

Overall, during the last few years, energy efficiency has got considerably publicity. Extreme phenomena, like heat waves, cold waves, storms, etc… are more and more present in our lives.

Concern about global warming and the dependency on fossil-based fuels have led to tightened environmental legislations, especially in area of European Union (EU). Legislation is forcing industry, e.g. electric motor manufacturers, to produce more and more energy efficient products. From June 16th 2011 all motors with rated output between 0.75 - 375 kW shall comply with IE2 efficiency class.

However, energy efficiency provides also a possibility to improve competitiveness.

Electrical Energy Usage in Industry

The cost of electricity used in electric motor is based - more or less - on global markets. It is also shown, according to IEA, that the most effective means of reducing CO2 emissions is improvements in energy efficiency.

In the EU industry, electrical motors are responsible appr. 70 per cent of industrial electricity consumption. Pumps, fans and air compressors are the most significant end-use applications.

Additionally, these devices operate with a notably lower efficiency than they could. Hence, in these applications, there are significant potential for improvements. The problem in discussion and improvements of energy efficiency is that improvements on the conversion efficiency are very often focused on individual components in the energy chain.

Frequency Converters in Fluid Handling Systems

Electrical motors and fluid-handling systems hold a major energy saving potential. Nowadays, electrical motor driven fluid handling applications are very common. In fluid handling systems, the best way to improve energy efficiency with a varying flow rate or output pressure demand is to replace throttle control scheme with a rotational speed control scheme. This is typically carried out with a frequency converter realizing the variable-speed operation of a high efficient (efficiency class IE2 or IE3) induction motor or in some cases a permanent magnet motor and hence a variable output from the fluid handling system.

Overall, with a frequency converter, it is possible to decrease energy, maintenance and production loss cost.

Dr. Mikko Valtonen
Product Manager, Motors
VEM motors Finland