Using of "Mathlab Fcn." For Realistic simulation of AC Motor Overload Protection

Abstract

Motor overload protection is a protection against overcurrent that may cause motor overheating which leads to motor damage. In overload protection relays, some techniques depend on current crossing the motor, motor thermal constants, operating time, and ambient temperature to estimate continuously the temperature of the motor. Therefore, it is closer to reality and can prevent inadvertent tripping. The paper proposes a new method to simulate this motor overload protection using MATLAB/Simulink. This method estimates continuously the percentage overtemperature of the motor. The "MATLAB Fcn" block is used to pass input values to a function in "MATLAB", to perform some calculations, and return a value in each step. This value determines whether the motor will keep running or not.