AC motor takes efficiency up a level

In the UK alone, there are an estimated 11 million motors installed, with a combined capacity of around 90GW. Increasing their average efficiency by 1% could deliver annual energy savings of around 1.5TWh and a reduce annual CO2 emissions by 600,000 tonnes. With these sorts of statistics, it is easy to understand why motor manufacturers are trying to re-design their products with energy efficiency in mind. One supplier has improved efficiency by much more than 1%. Baldor’s Metric-E+ AC motors use unique technology to boost efficiency to more than 96%. Baldor offers ‘EFF1’ choices – in line with Europe’s existing ‘high efficiency’ standard – plus a further choice of premium efficient motors it refers to as ‘EFF1+’, which are up to 2% more efficient. “Rising energy costs pose a major threat to industry competitiveness,” says Andrew Stephenson, project manager Metric-E+ at Baldor UK. “We now view Europe’s existing motor energy efficiency standards as too conservative – they keep inefficient products in use. Australasia and North America are showing Europe just what is possible in this area. We urgently need to raise the bar, and believe that EFF1 should be the minimum standard for most continuous processes and heavy duty applications.” The new motors span 17 different power ratings from 4 to 200kW (metric frame sizes are from D112M to D315M), with a choice of three speed options at each rating: 950rpm, 1450rpm and 2850rpm. In each case, says Stephenson, users can choose from ‘EFF1’ efficiencies or Baldor’s proprietary ‘EFF1+’ premium option. Maximum ‘EFF1+’ efficiencies at full load start at 90.1% for a 4kW motor and go up to 95.8% at 90kW (the end point for ‘EFF1’ labelling), continuing onwards to 96.3% at 200kW – the highest rated motor in the new range. Comparative ‘EFF1’ figures for the same motors are 88.5% at 4kW and 95.1% at 90kW. Stephenson believes that customers should look harder at the lifetime cost of motors. “The capital cost of a large electric motor is typically 2% of its lifetime cost,” he says. “These new motors will provide a major return on investment.” But how did Baldor achieve these higher efficiency levels? “By a more focused motor design, paying particular attention to the active materials,” says Stephenson. “Significant efficiency improvements were made by adding more copper to the windings in the motor and by upgrading the laminations to premium-grade, low-loss steel. By enhancing the design of the laminations, and the precision air gaps between the rotor and stator, we reduced fan and other losses inside the motor.” All Metric-E+ motors are wound with Baldor’s ISR (Inverter Spike Resistant) magnet wire, making them up to 100 times more resistant to the transient voltage spikes, high frequencies and short rise-time pulses that are commonly produced by inverters. This means all Metric-E+ motors are inverter-ready. The motors, with improved insulation materials, can withstand peak voltages of up to 1,600V peak for extra reliability. The motor is balanced to Baldor’s own very high standard, which, says Stephenson, leads to fewer mechanical stresses, particularly on motor bearings. “We are so confident in these new motors, we are offering customers a three-year warranty,” says Stephenson.