Abstract
Abstract: A DC motor is the most widely used actuator in the industry, especially for robotic applications such as position control of robot manipulators.  When  motor  is  used  in  high performance close loop motion control systems, an accurate model of motor is required for control system design [1,2] . Mathematical description of DC motor is divided into two subsystems :Electrical and mechanical subsystems. Electrical subsystem of a DC motor is simple. It consist of a resistor, an inductor and a back-EMF source. Nowadays , digital RLC meters can be found in nearly all labs. This paper study the reliability of model obtained by using a digital RLC meter. Results shows that although RLC meters can measure impedances easily and quickly ,  obtained values are not precious because RLC meter’ s  output current is in the range of mA while motor works with several Ampers.