Category: ELECTRICAL MACHINES

Compound Generator

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 aiding ampere-turns of the series field automatically increase with […]

Predetermination of External Characteristic

Predetermination of External Characteristic The Predetermination of External Characteristic of a 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 DC Generators

Characteristics of DC Generators: 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 of completeness […]

Self Excitation

Self Excitation: 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 Excitation generator with connection as shown in Fig. 7.24 is known as a shunt generator by virtue of the parallel connection of […]

Magnetization Characteristics

Magnetization Characteristics: 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 machine instead of […]

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