DC Machines

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 […]

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

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

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

External Characteristics of Compound Generator: External Characteristics of Compound Generator – The causes of voltage drop in the terminal voltage from no-load to full-load in a shunt generator can be partially/fully/over-compensated by use of an aiding series field (cumulative compound), which can be connected in a long- or short-shunt (long-shunt shown in. Fig. 7.34). The

External Characteristics of DC Shunt Generator: The External Characteristics of DC Shunt Generator can be predetermined from a knowledge of the OCC and armature and field resistances (which can be determined by simple dc test), without actually performing the load test which in fact is not feasible for a large generator. Assume for the time

Characteristics of Separately Excited DC Generator: With the advent of silicon-controlled rectifiers, the importance of the dc machine as a generator has considerably reduced as SCRs can be employed to draw dc power from standard ac supply and convert it to dc; also the dc voltage can also be varied with ease. For the sake

Self Excited DC Generator: Rather than arranging a separate dc source for excitation purposes, practical generators are always excited from their own armature terminals, this method of excitation being known as Self Excitation. A Self Excited DC Generator with connection as shown in Fig. 7.24 is known as a shunt generator by virtue of the

Magnetization Characteristics of DC Generator: The emf and torque equations, and power balance has been considered so far. The consideration of the Magnetization Characteristics in this section will set the stage for determining the performance of dc machines. Figure 2.3 depicted the magnetization curve of ferromagnetic material (iron) which is the B-H relationship. In a

Methods of Excitation of DC Generator: The performance characteristics of a dc machine are greatly influenced by the way in which the field winding is excited with direct current. There are two Methods of Excitation of DC Generator. Shunt excitation: Here the field winding is provided with a large number of turns of thin wire