Energy efficiency: Motors

Energy efficiency: Motors

Md. Mizanur Rahman, PhD School of Mechanical Engineering
Universiti Teknologi Malaysia UTM Cell phone: [phone]
E-mail: [e-mail]

Electric Motor Systems Efficiency

• Motor systems are the most important type of electrical load, ranging from small fractional kW to multi-MW motors.
• Motors consume over 50% of the total global electricity generated.
• In industry they are responsible for about two-thirds of the electricity

consumption.

• In the commercial and residential sectors motors consume slightly less

than 50% of the electricity.

• There is a vast potential for saving energy by increasing the efficiency of motors and motor systems

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Motor Systems Efficiency

• The efficiency of a motor-driven process depends upon several factors which may include:
• Motor efficiency
• Motor speed controls
• Proper sizing
• Power supply quality
• Distribution losses
• Transmission
• Maintenance
• Driven equipment (pump, fan, etc.) mechanical efficiency.

Motor Systems Efficiency

• The design of the process influences the overall efficiency (units produced/kWh or service produced/kWh) to a large extent.
• The largest opportunity for increased efficiency is in improved use of the mechanical energy (i.e. in the form of fluids or solid materials in motion) in the process.
• Process, Power line, optimizing each element and overall system.

Motor efficiency

• The losses of an induction motor as a function of the load.
• At low loads the core magnetic losses (hysteresis and eddy currents) are dominant
• Higher loads copper (I2R) losses are important.
• Mechanical losses are also present in the form of friction in the bearings and winding

Energy-efficient motors

• Earlier design: inefficient, minimized raw materials (copper, aluminium, and silicon steel).
• These induction motors had lower initial costs and were more compact but their running costs were higher.
• In the trend of efficiency and climate change, higher-efficiency motors are emphasized.
• Such motors feature optimized design, more generous electrical and magnetic circuits and higher quality materials.
• Efficiency improvements are possible with the use of superior materials (e.g., amorphous silicon steel) and optimized computer- aided design.