Induction Motor Calculations (IMC) Program

SimPhase Induction Motor Calculations (IMC) Program calculates the steady-state running conditions for one three-phase induction motor at a time. The IMC program uses induction motor standard per-phase equivalent circuit for the calculations.

The IMC program has 4 options :

  • Option 1 calculates the motor starting conditions at zero speed.
  • Option 2 calculates the maximum torque and the speed at which it occurs.
  • Option 3 calculates motor steady-state running conditions :
    • The motor has no variable frequency drive (VFD) speed control : Conditions are calculated for your combination of terminal voltage and frequency. The motor speed (or the slip) must be known before the calculations.
  • Option 4 calculates motor steady-state running conditions :
    • If the motor has no VFD speed control : Conditions are calculated for your combination of terminal voltage and frequency. The speed and the slip are unknown before the calculations. Image 1 below shows some results.
    • If the motor has a VFD speed control : Conditions are calculated for your value of motor speed. Image 2 below shows some results.

In option 1, if the selected motor has a VFD speed control, the program includes in the calculations the necessary voltage boost by the speed control.

Option 3 corresponds to conventional induction motor calculations using the standard equivalent circuit (voltage, frequency and speed (or slip) are known before the calculations).

Option 4 uses the information about the mechanical load provided when you define the motor.

Following blog post has examples using option 4.

Following image shows the values calculated by option 4 when the motor has no speed control. Notice that the speed and the slip are among the calculated values.

Motor has no speed control.
Image 1. Motor has no speed control. Some values calculated by option 4.

Following image shows the values calculated by option 4 when the motor has a VFD speed control. Conditions are calculated for a motor speed equal to 1000 rpm.

Motor has a speed control.
Image 2. Motor has a VFD speed control. Some values calculated by option 4.