Drives and Controls Magazine
US law could demand the world’s highest motor efficiencies
Published:  10 May, 2007

The US could have the world’s most efficient motors if proposals now before government committees are accepted and turned into legislation. The proposals, drawn up jointly by National Electrical Manufacturers Association (NEMA) and The American Council for an Energy Efficient Economy (ACEEE), cover motors with ratings from 745W to 370kW.

ACEEE, a non-profit organisation dedicated to advancing energy efficiency, estimates that the standards could save the US more than 8,000TWh by 2030, with cost savings to electricity consumers amounting to almost $500m.

Baldor Super-E motor

NEMA and ACEEE are proposing the adoption of mandatory minimum efficiency levels for three categories of electric motors. For general-purpose, polyphase induction motors in the range 1–200hp (0.745–150kW), they suggest that minimum efficiency levels should be raised to NEMA Premium levels, which are higher than the European Union’s Eff1 category. This level of efficiency is already required for motors bought by US Government organisations. Some motor manufacturers are already producing motors that exceed the Premium specification (including Baldor, whose Super-E motor is shown above).  

The second category covers seven specific types of low-voltage polyphase induction motor that were excluded from the EPAct standards published in 1992 - the first national standards covering motor efficiency in the US. These motors include U-frame designs, footless motors, close-coupled pump motors, eight-pole motors designed to operate at speeds of around 900 rpm, vertical solid-shaft normal-thrust motors, and all,polyphase motors up to 600V, other than those designed to operate on 230/460V supplies.

The third category covers a class of general-purpose low-voltage motors known as NEMA design "B", spanning ratings from 201–500hp (150–370kW).

NEMA and ACEEE have submitted their proposals to Congressional and Senate energy committees for possible inclusion in legislation now being developed. They suggest that the changes take effect 36 months after the legislation is enacted, and are requesting tax incentives for motor manufacturers and end-users to accelerate the production and installation of the Premium efficiency motors during this change-over period.

ACEEE argues that because most of the new motors will have a useful life of more than 20 years, any motors bought during the change-over will yield benefits for many years to come. It estimates that the tax credits would save an extra 0.7 billion kWh, worth $40m.