Can someone tell me why is transformer efficiency is higher than motor and generator? Transformer efficiency is generally greater than 95%, while that of the motors its ~70%. Both are electrical machines, so why's such a difference between the efficiencies?
PS: Edited By Admin. Added more description to make the question clearer to understand.
Motor or Generator has Mechanical loss (Friction loss & Windage), Core loss (Stator core & Rotor core) & Copper loss (Stator Cu & Rotor Cu).
Hence Generator/Motor has less efficiency than transformers.
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motors and generators have moving parts, and frictional losses as well as transmission losses at the bearings take place, which however do not take place in a transformer.
The efficiancy of trasformer is high because there are no dynamic losss it is a static device
The transformer is more efficient because , there is no moving device to lose energy mechanically as in case of DC motorsand generators , there is no air gap between two coils transferring energy in a transformation and there is no loss of energy in making AC to DC and DC to AC by using convertor or commutators and carbon brushes
Adding one more point to the discussion, the main difference between the transformer and motor is that its structure and performance, transformer has primary and secondary winding used to set up or set down the supply voltage or current at the output. Whereas motor is made of stator and rotor which when excited with input electrical energy converts into mechanical energy.
Coming to the efficiency due to the copper losses and frictional losses which is more in motor the efficiency of motor is less than that of transformer whose copper loss is less.
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