# Electrical – Measuring R1 in induction motor equivalent circuit and parameter extraction from test

induction motor

I always had this question that I never really found written anywhere and I have the good or bad habit of not believing my teachers when answering this kind of odd questions.

Whenever I read about the induction motor equivalent circuit R1 is always the resistance of the stator winding. Great! I have a stator, how do I get R1?

My first guess is to measure the resistance value between one phase and neutral in Y (star) connection. That or take the resistance value between phases in Delta connection and divide it by 1.5 to get the resistance of only the winding that connects them directly.

Second question:
To extract the parameters of the equivalent circuit, I tested the motor in Delta connection, with the rotor blocked and in free running mode. Is V1 the phase to phase voltage? What about Is? Should I test it in Y instead? I have V(t) (phase to phase) and I(t) that I got using an oscilloscope and a current probe.

Equivalent circuit with variable names:

(source: myelectrical.com)