Braking of DC Motors: Controlled slowing or stopping of a motor and its driven load is as important as starting in many applications (e.g. cranes, traction on a slope to avoid excessive speed, etc.). Braking of DC Motors methods based on friction, electromechanical action, eddy-currents, etc. are independent of the motor but sometimes electric braking […]
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Ward Leonard Method of Speed Control of DC Motor: Ward Leonard Method of Speed Control of DC Motor is combined armature and field control and is therefore, operationally the most efficient method of speed control with a wide range. The dc motor armature is fed from a variable voltage and adjustable polarity supply whose current
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Series Parallel Control of DC Motor: Series Parallel Control of DC Motor – Here two identical motors are coupled together mechanically to a common load. Two speeds at constant torque are possible in this method one by connecting the motors armatures in series and the other by connecting them in parallel as shown in Fig.
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Shunted Armature Speed Control: Shunted Armature Speed Control – It is a variation of rheostatic control. As is obvious from Fig. 7.59, the principle used in achieving control is that of voltage division. In the shunt motor armature control circuit of Fig. 7.59(a) the Thevenin equivalent as seen by motor armature is drawn. The no-load
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Rheostatic Control Method: Rheostatic Control Method – Series armature-resistance control : Here the applied armature voltage is varied by placing an adjustable resistance Re in series with the armature as shown in Fig. 7.58 along with the speed-torque characteristics. Some of the limitations of the rheostatic control methods are enumerated below: (i) Only speeds below
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Armature Control Method: The main requirement of this Armature Control Method scheme is a variable voltage supply to the armature whose current rating must be somewhat larger than that of the motor. It is superior to the field control scheme in three respects, outlined below: 1. It provides a constant-torque drive. In the shunt motor
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Field Control Method of DC Shunt Motor: The Field Control Method of DC Shunt Motor are in general much more adaptable speed drives than ac motors which are associated with a constant-speed rotating field. Indeed one of the primary reasons for the strong competitive position of dc motors in modern industrial drives is the wide
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Starting of DC Motors: At the time of Starting of DC Motors (n = 0), the induced emf of a motor is zero such that the current drawn from rated voltage supply would be for a shunt motor. The series field resistance would be included in the denominator for a series motor. For large motors
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Speed Torque Characteristics of DC Series Motor: To find the Speed Torque Characteristics of DC Series Motor, let us analysis the figure 7.43 shows the connection diagram of a dc series motor. The speed for this motor is and the torque equation is Consider at first the case of linear magnetization, i.e, These relationships are
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Characteristics of DC Motors | Characteristics of Shunt Motor: The power of the dc motor lies in its versatility and ease with which a variety of speed-torque characteristics can be obtained, and the wide range of speed control which is possible without the need of elaborate control schemes while a high level of operating efficiency
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