SimPhase Induction Motor Calculations (IMC) Program

SimPhase IMC program calculates the steady-state running conditions (speed, slip, real power input, power factor, stator current, efficiency, etc.) of three-phase induction motors for any combination of mechanical loading and stator voltage.

For each motor, the equivalent circuit is used for the calculations. In order to use an equivalent, we need :

  1. An estimate of the slip
  2. An estimate of the stator voltage

The motor slip itself is a function of the loading and a function of the stator voltage. This must be considered even if you estimate your own value for the slip (using nameplate data for example).

The IMC program can estimate a more accurate value for the slip.

The program calculates the steady-state operating point (intersection of motor torque-speed characteristic and mechanical load torque-speed characteristic). Effects of stator voltage deviations (even large ones) are thereby included in the calculations.

This article What Slip Value Should We Use in Induction Motor Calculations has a more detailed analysis.

The program can calculate the running conditions for induction motors equipped with variable frequency drives (VFD) speed controls. For each motor, the user specifies the wanted speed. The program then calculates the voltage amplitude and the synchronous frequency that are required in order to obtain that speed.

Following image shows the calculated conditions for a 50 HP induction motor with a loading equal to 70% of full-load torque and a 0.85 per unit stator voltage.

One possible application of the IMC program : With multiple simulations you can study how the efficiency (or any other motor condition) varies when the loading (or the voltage) varies.

Version 4.7 was released in April 2019. Latest update is (February 2020).

There is a free version of the IMC program. It has some limitations but you can use it for as long as you want.

There is also a licensed version of the IMC program.