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DC Machine Applications

DC Machine Applications Whenever the application of any machine is considered, its operating characteristics along with its economic and technical viability as compared to its competitors are the essential criteria. For a DC Machine Applications, of course, the main attraction lies in its flexibility, versatility and ease of control. This explains why in spite of …

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Separately Excited DC Motor for Dynamic Analysis

Separately Excited DC Motor for Dynamic Analysis: Separately Excited DC Motor for Dynamic Analysis – The DC machines are quite versatile and are capable of giving a variety of V-A and speed-torque characteristics by suitable combinations of various field windings. With solid-state controls their speeds and outputs can be controlled easily over a wide range …

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Hopkinsons Test on DC Machine

Hopkinsons Test on DC Machine: This is a regenerative test in which two identical dc shunt machines are coupled mechanically and tested simultaneously. One of the machines is made to act as a motor driving the other as a generator which supplies electric power to motor. The set therefore draws only loss-power from the mains …

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Braking of DC Motors

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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Shunted Armature Speed Control

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: 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

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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