Electric motor efficiency calculation

In summary, the conversation discusses the calculation of electric efficiency for 3 phase electric motors and the confusion surrounding the power factor. The formula for efficiency is given as work out divided by work in, with work being equal to power multiplied by time. The importance of accurately measuring the mechanical output and defining the operating point for efficiency calculations is also mentioned.
  • #1
Nevalite
1
0
Hello everyone,

I am trying to calculate the electric efficiency of some 3 phase electric motors but I am a little confused about the power factor.

efficiency=work out/work in

work out=rated W of my motor (hp*745.7)

work in= V*A*PF*√3

Is the work in correct?

Thanks
 
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  • #2
Your formula is for POWER. Work is Power * time. Balanced 3 phase P = V*A*PF*√3.

Work = Energy = P*T ( You pay for Kilowatt Hours - not Kilowatts)

However the trick in this type of project is typically accurately measuring the mechanical output - needing a calibrated dyno - or other device.

Also - for efficiency it is important (or more meaningful) to define what the operating point is for the efficiency calculation / measurements. --e.g. A Cold motor is more efficient then a warm motor - etc.
 

Related to Electric motor efficiency calculation

What is an electric motor efficiency calculation?

An electric motor efficiency calculation is a way to measure the effectiveness of an electric motor in converting electrical energy into mechanical energy. It is typically expressed as a percentage and can vary depending on factors such as motor design, operating conditions, and load.

Why is it important to calculate the efficiency of an electric motor?

Calculating the efficiency of an electric motor is important because it allows us to understand how effectively the motor is using electricity. This information can be used to optimize motor performance, reduce energy waste, and save money on electricity costs.

What factors affect the efficiency of an electric motor?

The efficiency of an electric motor can be affected by a variety of factors, including the design and quality of the motor, operating conditions such as temperature and voltage, and the load placed on the motor. Other factors such as friction, resistance, and mechanical losses can also impact efficiency.

How is electric motor efficiency calculated?

Electric motor efficiency is typically calculated by dividing the output power (mechanical energy produced by the motor) by the input power (electrical energy supplied to the motor). This result is then multiplied by 100 to get a percentage. The formula for calculating efficiency is: Efficiency = (Output Power / Input Power) x 100.

What is a good efficiency percentage for an electric motor?

The efficiency percentage for an electric motor can vary depending on the type of motor and its operating conditions. However, in general, a good efficiency percentage for an electric motor is considered to be around 85-95%. This means that the motor is effectively converting a high percentage of electrical energy into mechanical energy.

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