This paper describes the effect of sampling time on the speed control of a separately excited dc motor which uses phase controlled bridge converter and fuzzy logic control. In order to accomplish a satisfactory damping characteristics over a wide range of operation the speed deviation (Aw) and the acceleration (Cie) were taken as input signals to the fuzzy controller. These variables have significant effects on the damping of shaft mechanical oscillations. The method used for defuzzification is the commonly used centroid method. By changing the sampling time over a wide range the results obtained by fuzzy logic controller are compared with those obtained by using conventional controllers.