DC Generator Characteristics

Wound-field DC machine

As shown by equation 1, the terminal voltage of the separately excited DC generator would be expected to decrease in a linear manner due to the voltage drop across the armature circuit resistance. $\begin{matrix}   {{V}_{t}}={{E}_{a}}-{{I}_{a}}{{R}_{a}} & {} & \left( 1 \right)  \\\end{matrix}$ Figure 1 shows the linear decrease that would …

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DC Generator Operation

Complete equivalent circuit of a separately excited DC generator

When operated as a generator, the armature of the DC machine is driven by a prime mover. As the armature coils move through the flux created by the stator field, a voltage is induced in them. To understand the operation of the DC generator we need a specific relationship for …

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Inductors in AC and DC Circuits

basic inductor

The main action of an inductor is to resist a change in current.  However, since the current in a DC circuit is constant, there is no induced voltage developed instantaneously across the inductor.  The inductor does resist the initial inrush of current based on the time constant of the circuit. …

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Capacitors in AC and DC Circuits

Difference between Capacitor and Battery

Capacitors in DC Circuits             When a capacitor is placed in a DC circuit that is closed (current is flowing) it begins to charge. Charging is when the voltage across the plates builds up quickly to equal the voltage source. Once a capacitor reaches its fully charged state, the current …

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Synchronous Motor Working Principle

Wound Rotor & Squirrel Cage Induction Motor Theory

The synchronous motor is identical in construction to the synchronous generator, although virtually all synchronous motors are of the salient-pole type. Like all electric motors, the synchronous motor converts electrical power into mechanical power. The primary difference in operation, however, is that the synchronous motor only delivers torque and power …

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Synchronous Generator: Performance and Analysis

Plot of power vs. power angle for a salient-pole synchronous generator

Most of the electricity we use on a daily basis is created by synchronous generators. Synchronous generators produce constant-frequency power and can operate at both leading and lagging power factors. Delivered power for the round-rotor machine From figure 1, we can write a voltage equation: $\begin{matrix}   {{E}_{a}}={{V}_{t}}+jI{{X}_{s}} & {} & …

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Synchronous Machine Equivalent Circuit

Per-phase synchronous machine equivalent circuit

In the Synchronous Machine section, we have seen that there are two rotating magnetic fields in the airgap of the synchronous machine whether it is operating as a motor or as a generator. Any time a magnetic field passes by a conductor, it will induce a voltage in the conductor. Thus, …

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Synchronous Generator Working Principle

In this section, we will describe the operation of the synchronous generator. Figure 1 shows a cross-section of a round-rotor synchronous generator, and Figure 2 shows a cross-section of a salient-pole synchronous generator. Both are two-pole synchronous generators. The primary difference between the two types is evident from looking at …

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Cutaway view of a synchronous motor

The synchronous motor, like all other rotating motors, has a stator and a rotor. Figure 1 shows a cutaway view of a synchronous motor. The rotor contains electromagnets, which create the field of the motor. In some cases, permanent magnets are used on the rotor of a synchronous machine to …

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Pulse Width Modulated Inverter | PWM Inverter

Sinusoidal pulse-width-modulation

The Pulse Width Modulated (PWM) inverter offers the ability to change both the magnitude of the voltage and the frequency using a fixed DC voltage as the input. This means a diode rectifier can be used as the front end of the drive, which appears as a constant power factor load …

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