ABSTRACT

KIFAYA. Separately Excited DC Motor Model (supervised by Rhiza S. Sadjad and Yustinus Upa Sombolayuk).

The mathematical model of separately excited DC motor is derived from 3 (three) equations, i.e. the armature equation, the field equation and the torque equation. By assuming constant field current (armature-controlled linear model) and constant armature current (field-controlled linear model) respectively, the non-linear model of separately excited DC motor is verified using the nominal values of input voltages and loads. In this case, numerical data of DRIPPROOF S – 600 HP type DC motor specifications (from US Electrical Motors) have been used.

The simulation has shown that the step response of the model has a maximum overshoot of starting armature current up to 11 times the nominal value. Adding resistors in series with both armature and field windings only reduces the maximum overshoot of starting armature current up to 3.15 times the nominal value. On the other hand, increasing slowly both the armature and field voltages from 0 to their nominal values (in the period of minimum 20 seconds) can eliminate the armature current overshoot.