Clearing the air on ‘MEPS2’ compressors

THE latest revision to the MEPS scheme has raised the benchmark of electric motor efficiency in Australia.

THE latest revision to the MEPS scheme has raised the benchmark of electric motor efficiency in Australia.

The onus is now on the compressed-air industry to ensure ‘MEPS2’-compliance, and to leverage the resultant energy savings from improved motor efficiencies.

In an era when efficient use of energy resources is in the spotlight, businesses, governments and communities everywhere are being called upon to find new ways to cut energy usage.

Nowhere is this more apparent than in the compressed-air industry – approximately 10% of power is used in this country is used in compressing air.

In such a power-intensive operation, the effect of even a small efficiency gain is magnified when applied across the whole industry.

A case-in-point is the use of more efficient electric motors in compressed-air systems. ‘Minimum Energy Performance Standards’ (MEPS) have governed the use of electric motors in Australia since the Australian Greenhouse Office (AGO) introduced the system in 2001.

In April 2006, however, the mandatory standards were revised upwards. A more stringent set of requirements, known as ‘MEPS 2006’ or ‘MEPS2’, was published and came into force.

For the compressed-air industry, the legislation covers three-phase electric motors from 0.73kW up to, but not including, 185kW.

The requirements of this legislation, covering both imported and locally manufactured motors, are set out in the Australian standard, AS/NZS 1359.5-2005 Rotating electrical machines which defines two levels of efficiency for electric motors: the base MEPS level performance and a ‘high-efficiency’ level.

MEPS compliance

According to Champion Compressors engineering manager, Andrew Fraser, the onus is on motor and equipment importers to ensure that their products conform to Australian MEPS2 requirements.

Further, each motor must be registered in an online database, in accordance with AGO procedures.

“While the system relies on self-regulation by the industry, compliance is mandatory,” Fraser said.

“The AGO has the right to stop the sale of a product if it is found to be non-compliant.”

A consequence of this is a degree of risk for suppliers of equipment incorporating electric motors, if they cannot show that the packaged motor is compliant.

While the responsibility for compliance rests with the motor supplier, manufacturer’s representative or motor importer, it is in end-users interest to know that their equipment is MEPS2-compliant.

Fraser says that overseas standards are not identical to Australia’s MEPS2 system.

It cannot be assumed that motors complying to the European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP) or the US Energy Policy Act (EPAct) can be used legally in Australia.

Importers of air compressors therefore need to ensure that the overseas-built machines conform to the Australian standards.

Similarly, importers need to ensure that electric motors integrated into other equipment, but capable of being used in ‘stand-alone’ mode, are also compliant, and have been properly registered for use in this country.

For compressor manufacturers and importers, the simplest way to adhere to the MEPS2 requirements is to build-in compliance from scratch.

According to Fraser, design changes in typical motors, introduced to achieve higher efficiencies, have resulted in generally reduced starting torques, and in some cases, larger frame sizes.

The need for larger frames is due to the larger volume of active material required to achieve the efficiency levels required.

The larger motors can be dealt with in a number of ways, depending on the compressor design philosophy.

As with any new development, the technology behind the improved electrical motors does have a cost impact. However, the higher capital expenditure is compensated for by the power savings and lower compressor life time operating costs.

Fraser points out that the payback period may vary, depending on the extent of use of the compressor.

“An operator that only uses the compressor occasionally, or on light load cycles, faces a much longer payback period than an operator using the machine more often, or on heavier demands,” he said.

Beyond MEPS

Fraser says the efficiency improvement for MEPS2-compliant motors used in compressors is generally slightly less than 1%, which corresponds approximately a 10 to 20% reduction in internal motor losses.

While this improvement may sound small, over the life of the compressor, the energy and cost savings become significant.

Similarly, provided all compressor manufacturers supply equipment incorporating MEPS2-compliant motors–and by law, this should be the case–the impact across the industry becomes even more significant.

In the continuing drive to improve energy efficiencies and reduce operating costs, there is incentive to go beyond the mandatory requirements of MEPS2, and introduce additional measures wherever possible.

According to Fraser, innovations in compressor design provide for additional efficiency gains.

“While Champion recognises the importance of MEPS compliance, we also understand that the motor is not the only source of efficiency gains.

“By thoughtful compressor design, significantly larger efficiency improvements are possible,” he said.

For Australia to reap the full benefits, the obligation is now with the compressed-air industry to adhere to the policy of MEPS self regulation.

“For MEPS to be truly successful in the compressed-air industry, the electric motors used in the compressors must be both MEPS2 compliant and registered in the AGO’s online database,” Fraser said.

“It is up to the industry to take on this responsibility.”