There is an urgent need to improve the energy efficiency of electric motors, particularly in South Africa.

This was highlighted at the switchgear and dives conference, held in Midrand, north of Johannesburg, earlier this year.

Given the country’s current power woes, and the focus on energy efficiency in South Africa, and globally, manufacturers are working towards assessing ways to improve the energy efficiency of electric motors.

Electric motors consume about 60% of the total electricity used by South African industries. State-owned power utility Eskom reports that replacing 5 000 electric motors will result in a saving of 2 482 MW.

The country’s energy challenges have exacerbated the need for the development of programmes, particularly Eskom’s demand-side management programme, which, in turn, established the energy efficient motors programme.

Variable-speed drive supplier Vacon product manager Hans Carlsson and tech- nology director Michael Bjorkman compiled a report, ‘Energy saving opportunities with motors and drives’, which was also presented at the switchgear and drives conference.

The report indicated that savings in Europe had been achieved as a result of encouraging the use of higher-efficiency motors, and the report suggested that even bigger savings could be achieved with the use variable-speed drives.

The report pointed out that reducing energy consumption resulted in less carbon dioxide (CO₂) emissions, as well as reduction in the running costs of installations.

In addition to energy efficient motors, the use of variable-speed drives also reduced energy consumption, as only the energy that is needed in a process is drawn from the main electricity supply. The report states: “The greatest savings are seen in [the use of drives in] pump and fan applications.”

When less electricity is used in running a motor, there are lower losses in the transmission and distribution of electricity. Less electricity has to be generated for high- efficiency motors, the report highlighted, as well as that, at the beginning of the electricity supply chain, less coal is burnt, which also reduces CO₂ emissions.

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