How does the efficiency of a motor vary with load?
Most electric motors are designed to run at 50% to 100% of rated load. Maximum efficiency is usually near 75% of rated load. Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp. A motor’s efficiency tends to decrease dramatically below about 50% load.
What is motor rated power?
Electrical motors are rated in horsepower or watt Power is in general rated in watt (W) or horsepower (hp). The unit of electric power – 1 watt – is equal to the power produced by an electrical current of 1 amp at a potential difference of 1 volt.
How is power consumed by a motor related to load?
power consumed is a slippery term, for example the first law of thermodynamics puts it at 0 motors produce heat mostly by electric resistance, so heating is proportional to the current flowing through the motor, current is basically proportional to torque, so that increases with load too.
What happens if current drawn is less in no load condition?
hence if current drawn by the motor is less then the input power to be applied to it , will also be less. so for operating motor in no load condition less power will require as current drawn is reduced. u can calculate exact amount of current at no load condition,and then the input power.
How is the power factor of a motor determined?
Figure 2 Motor Power Factor (as a Function of % Full-Load Amperage) Overloaded motors can overheat and lose efficiency. Many motors are designed with a service factor that allows occasional overloading. Service factor is a multiplier that indicates how much a motor can be overloaded under ideal ambient conditions.
How does an external load affect a motor?
If an external load reduces the speed of the motor, that “back emf” is reduced (the resistance of the motor decreases ), increasing current in order to maintain the voltage, and thus power increases. Your friend is incorrect. The rating on a motor is the rated power that the motor produces at the shaft.