The Open-Circuit Condition of a Transformer In the open-circuit condition (Fig. 12) a transformer is effectively turned into an iron-cored coil whose winding w1 is connected across a source of a Sinusoidal voltage. For this reason, the phasor diagram for a transformer in the open-circuit condition (Fig. 13) is not unlike that of an iron-cored […]
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Electricity and Magnetism
The Equivalent Circuit and Phasor Diagram for an Ideal Single-Phase Transformer
The Equivalent Circuit and Phasor Diagram for an Ideal Single-Phase Transformer At this stage we will consider an ideal single-phase transformer in which the core is fabricated from a ferromagnetic material whose hysteresis has to be included in consideration (see Fig.6 b). With the secondary circuit open-circuited, this ideal single-phase transformer has the same […]
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Operation of a Single-Phase Transformer
Operation of a Single-Phase Transformer In sketch form, the arrangement of a single-phase transformer is shown in Fig. 5 a. On the secondary side, where the winding has W2 turns, the transformer acts as a supply source for a load whose resistance is r2,load . On the primary side, where the winding has W1 turns, […]
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Transformers
Transformers General A transformer is a static electric device (that is, one free from rotating or moving parts) most often used to convert one alternating voltage to another alternating voltage (or other alternating voltages) at the same frequency by mutual induction. A transformer has at least two windings linked by a common magnetic flux but […]
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A.C. Commutator Machines
A.C. Commutator Machines A most valuable quality of d.c. motors is that their speed and torque can be controlled gradually and economically. However, on a commercial scale electricity is generated in the a.c. form which has first to be converted to d.c. in order to make it available to d.c. motors. This makes the use […]
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The Compound Motor
The Compound Motor The shunt motor has a flat speed-torque characteristic and the series motor has. a falling speed torque characteristic . in some applications it is desirable to have some intermediate from . the simplest way to achieve this objective is to use a compound motor. In a compound motor motor, one winding (series […]
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The Series Motor
The Series Motor In a series motor the armature current is at the same time its field current, because the field winding is connected in series with the armature winding (Fig. 45). Owing to this connection the main magnetic flux of the machine varies III direct proportron to the armature current so long as the […]
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The Shunt Motor
The Shunt Motor In a shunt motor, the armature circuit is connected in parallel with the field circuit. Therefore, the field current in a shunt motor is independent of the armature current and the load on the motor. The basic form of connection for a d.c. motor to a starting rheostat, rs, and a field […]
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Motor Action
Motor Action Owing to the identity of generator and motor structure, a generator may be made to operate as a motor . this is especially simple to do in the case of a shunt generator operating into a d.c. line . in this case, it will suffice to bring down the field current so that […]
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Parallel Operation of Shunt Generators
Parallel Operation of Shunt Generators In practice cases often occur where it is advantageous to feed loads from two or more generators operating in parallel. Let us see how this is done, taking the simplest example. that of shunt generators. Suppose we are to bring a second generator (Fig. 34) into a line where a […]
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