Industry has two years to comply with motor regulations
EU legislation means motors have to be made much more efficient. Tom Shelley investigates the potential impact
New staged legislation is coming into force that will require industrial users to use electric motors that achieve higher efficiencies.
One of the ways of meeting, and even exceeding, such requirements is to turn to permanent magnet motors. These additionally achieve higher torques at low speeds, and being synchronous, require no speed feedback. A leading drive maker is currently rolling out software that will allow most of its products to power such motors.
Permanent magnet motors rated up to 5MW are already the norm for niche applications, such as the steerable propeller pods of large ships, pulp and paper making machines and even wind turbines.
European Union regulations on minimum efficiency standards for industrial electric motors were unanimously voted on in March. These regulations, which form part of the EcoDesign Requirements for Energy-Using Products Directive, require that from June 2011 motors must meet the IE2 standard. From 2015, motors from 7.5kW to 375kW must meet IE3.
For a 1kW motor, roughly 8% its input energy is saved by going from IE1 to IE2, and by going from IE1 to IE3, around 11%. The typical efficiency of an IE2 1kW motor is 80%, while similarly sized IE3 motors exceed this significantly. The requirements will extend down to 0.75kW from 2017. But many feel the legislation doesn't go far enough.
"We would have liked to see the inclusion of explosion proof motors," says ABB UK general manager for drives and motors, Steve Ruddell. "We estimate these to be about 10% of the motor population.
"And, why stop at 375kW? All motor powers should have been included. We think that any motor that doesn't meet the appropriate efficiency class shouldn't be allowed to be rewound and should be scrapped."
However, the real incentive is higher efficiency motors save money. The purchase price of an electric motor is normally less than the cost of its electricity consumption over 30 days.
Despite the relatively low cost of electric power in Sweden, €0.03 per kWh, the Swedish company LKAB found that it could save itself €440,000 a year by achieving just a 1% improvement in motor efficiency. It has since decided to specify only IE3 efficiency motors that are optimised for a 75% load.
Global marketing director for ABB, Roelof Timmer, said: "Other applications, such as pulp and paper and wind turbines, only take about 1% of the market. But, permanent magnet motors are beginning to get going. One application the technology is particularly suitable for is micro hydro water turbines. Because they are synchronous, a variable speed drive for permanent magnet motors is essential."
From a hardware perspective, drives for AC induction and permanent magnet motors are identical, but they do need some special software. The price of suitably equipped drives is about 5 to 10% higher and the motors themselves do cost more. But, costs are starting to come down.
Pod designs the way forward for ship propulsion
Motors for ships can be fitted to conventional propellers, but much advantage can be obtained by fitting them inside pods under the stern of the ship. These can be rotated through 360º to improve manoeuvrability, particularly for cruise liners, or in the case of the ice breaking ships, pull them in reverse so they break the ice with their reinforced sterns.
Azipod propellers are found to be more efficient if they pull, rather than push. The 158,000 tonne Royal Caribbean Cruise Liner, Freedom of the Seas, uses three 14MW Azipods. But these will soon be dwarfed by the 220,000 tonne, Oasis of the Seas, to be launched later this year by STX Europe at Turku, Finland. Her sister ship, Allure of the Seas, will be launched in 2010.
These monsters, which will carry 5,400 passengers and 3,000 crew, will be powered by three 20MW Azipods with electromagnet synchronous rotors and shaft mounted exciters. Power is delivered to the rotatable motor pods through slip rings. The motors run at between 100 and 180rpm.
So far, 165 Azipod units have been installed for operation on around 75 ships. As well as improving manoeuvrability, they reduce the amount of engine room space required inside the hull and cut down on noise and vibration. They are also said to be more hydrodynamically efficient than propellers projecting from the stern of a ship.
Why are the new regulations needed?
The new and tighter regulations for improved efficiency of electric motor designs and installations under Directive 2005/32/EC are due to come into force mid year 2009 and will start to deliver serious energy savings by 2011.
The EU Commission estimates that there are 85 million large electrical motors in the Community Market. These consume 70% of the energy used within industry amounting to 1067TWh in 2005, corresponding to 427millon tonnes of CO2 emissions.
Without these regulations, it is predicted that this will increase to 1252TWh by 2020. It has been concluded that the life-cycle energy consumption and the use-phase electricity consumption can be improved significantly, in particular if motors in variable speed/load applications are equipped with drives.
The directive, specifying eco-design requirements for motors and their drives will be introduced in three stages. By 2011 all new motors will have to meet the IE2, high efficiency rating. By 2015, all industrial motors between 7.5kW to 375kW must either meet the higher IE3, premium efficiency, rating or meet IE2 rating and utilise an electronic drive. By 2017, these requirements will be extended to all electric motors in the range of 0.75kW to 375kW.
It seems, at long last, that the well known energy saving benefits of electronic variable speed drives in conjunction with electric motors have been recognized formally. Even an IE3 motor should not be seen as an alternative to a variable speed drive. For the majority of variable-torque fan and pump applications the use of a drive with an IE3 motor gives the best benefit for lifetime cost and energy consumption.
"In most cases, the additional initial capital outlay of buying higher efficiency motors and variable speed drives should be recouped relatively quickly through reduced energy bills," says Control Techniques' John Murphy, VP Strategic Planning. "We have considerable experience in improving installed motor energy efficiency with variable speed drives together with our sister company Leroy Somer, one of Europe's leading motor manufacturers. Control Techniques can advise on the most cost-efficient route to Directive 2005/32/EC compliance."
* EU regulations are to require 'high' and then 'premium' efficiency motors to be used in industrial applications
* Permanent magnet motors offer even higher efficiencies and facilities are being added to inverter drives to accommodate them
* Permanent magnet motors for rotatable pods for ships are made up to 5MW. Larger pod powers are presently achieved using synchronous electromagnet rotors, powered by common shaft mounted exciters
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