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 
               2
     copper  (I R) 
     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.