External Characteristics of DC Shunt Generator

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 …

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Self Excited DC Generator

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 …

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Magnetization Characteristics of DC Generator

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 …

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Commutation in DC Machine

Commutation in DC Machine or Generator or Motor: One coil each under an adjoining pole-pair is connected between adjacent commutator segments in a lap-wound dc armature, while in a wave-wound armature the only difference is that P/2 coils under the influence of P/2 pole-pairs are connected between adjacent segments. Coil(s) current is constant and unidirectional …

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Armature Reaction in DC Machine

Armature Reaction in DC Machine: When the armature of a dc machine carries current, the distributed armature winding produces its own mmf (distributed) known as armature reaction in DC Machine. The machine air-gap is now acted upon by the resultant mmf distribution caused by simultaneous action of the field ampere-turns (ATf) and armature ampere-turns (ATa). …

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Circuit Model of DC Machine

Circuit Model of DC Machine: The parallel paths of DC machine armature are symmetrical and each has an induced emf Ea and a resistance Rp. The armature can be represented by the Circuit Model of DC Machine¬†with voltage Ea and a series resistance as shown in Fig. 7.5. The armature resistance is quite small so …

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