ELECTRICAL POWER AND EFFICIENCY
The electric power in watts represents the rate at which energy is converted from the electrical energy of the moving charges to some other form, as heat, mechanical energy, or energy stored in electric fields or magnetic fields.
The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression). If energy output and input are expressed in the same units, efficiency is a dimensionless number.
Power (W) cc P=UI=U2/R=RI2
ca single phase P=UIcosφ
ca three phases P=31/2UIcosφ(delta
El. motor efficiency µ=746 Pout / Pin
Pout = power delivered to shaft (hp);
Pin = electrical power consumed (W)
PDF document : Power efficiency