Induction Motors: Power Consumed vs Power Delivered

In summary, the power consumption of a three phase induction motor is given by the equation P = sqrt(3)*V*I*(PF). This is the same as the power delivered to the motor. However, the power output (mechanical power on shaft) may differ from the power input due to losses in the motor. The efficiency of the motor will determine how much of the power input is converted to mechanical power output.
  • #1
Bergenheimer
10
0
Hello

The equation for power consumption of a three phase induction motor is given by the equation:

P = sqrt(3)*V*I*(PF)

Does this differ from the power that is delivered to the motor. For example, if a motor is running at 460 volts, 30 amps with a PF of 0.82, then the power consumption is

P = sqrt(3)*460*30*.82 = 19.6 kW

What is the corresponding power being delivered to the motor? is it the same value? Just want to know if the power being delivered to the motor is different than the power the motor actually consumes.



Bergenheimer
 
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  • #2
Hi
One basic question, how it would be possible, that power delivered wouldn't be consumed ?

Equations you are writing here are describing power delivered = consumed (consumed in many ways - iron losses, copper losses, friction, ventilation, mechanical power output).

There is one more thing: difference between power output (mechanical power on shaft) and power input (your equations). Maybe you are referring to this ?
 
  • #3
Hello Berg:

Your OP - refers to "power consumed" and "Delivered to", these are the same thing and referring to the electrical circuit - a matter of perspective, from the sources perspective or from the motors perspective. It is the Mechanical Power (shaft) output of the motor that will not equal these values due to losses in the motor - both electrically and mechanically. The better the motor - the better the efficiency etc.
 

1. What is the difference between power consumed and power delivered in an induction motor?

Power consumed refers to the total amount of energy used by an induction motor to run, including any losses due to friction or resistance. Power delivered, on the other hand, refers to the useful output power that is converted into mechanical energy to perform a specific task.

2. How does the power factor affect the power consumed and delivered in an induction motor?

The power factor is a measure of the efficiency of an induction motor, and it is the ratio of the power consumed to the power delivered. A lower power factor means that the motor is less efficient, and more power is being consumed compared to the power being delivered.

3. What factors can affect the power consumed and delivered in an induction motor?

The power consumed and delivered in an induction motor can be affected by various factors such as the size and design of the motor, the load being driven, the speed of the motor, and the power supply voltage. Other external factors such as temperature and humidity can also impact the motor's performance.

4. How can we measure the power consumed and delivered in an induction motor?

The power consumed and delivered in an induction motor can be measured using a wattmeter or a power analyzer. These instruments can measure both the voltage and current in the motor and calculate the power consumed and delivered using the formula P=VI, where P is power, V is voltage, and I is current.

5. What are some ways to improve the power factor and efficiency of an induction motor?

To improve the power factor and efficiency of an induction motor, it is essential to properly size and design the motor for the specific load and application. Regular maintenance and proper lubrication can also help improve the motor's efficiency. Additionally, using variable frequency drives or soft starters can help reduce the motor's power consumption and improve its power factor.

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