A big change in motor efficiency

By December 19, 2010, federal regulators will require that certain motors sold in the United States exhibit specific energy-efficiency performance under the Energy Independence and Security Act (EISA) of 2007. Are you ready for this change?

Figure 1. Typical induction motor found in a plant.

The pertinent portion of EISA that affects motors that plant engineers might select is the section on Electric Motor Efficiency Standards. Here’s what you can do to prepare for these changes.

In a nutshell

EISA reclassified general-purpose motors, 1 hp to 200 hp, as Sub-type I, and defined a new category of general-purpose motors as Sub-type II. Sub-type II motors are similar to Sub-type I motors, except they’re configured as:

• U-Frame motors
• Design C motors
• Close-coupled pump motors
• Footless motors
• Vertical solid-shaft normal-thrust motors
• Eight-pole motors
• Poly-phase motors using less than 600 volts

Sub-type II motors between 1 hp and 200 hp manufactured alone or as part of another piece of equipment are required to have a nominal full-load efficiency not less than as defined in NEMA MG-1 (2006), Table 12-11. For this same 1 hp to 200 hp range, Sub-type I motors will have nominal full-load efficiencies that meet the levels defined in NEMA MG-1 (2006), Table 12-12. The efficiencies in Table 12-12 are greater than in Table 12-11 by as much as three percentage points. Also, for the first time, the efficiency of motors between 200 hp and 500 hp is required to conform to NEMA MG-1, Table 12-11 (Table 1).