Home / Synchronous Machines

Synchronous Machines

Three-Phase Generator

Three-Phase Generator | Construction | Voltage Regulation | Rating

This guide covers three phase generator construction, voltage regulation, its rating, cooling methods, excitation control and several solved examples. The three-phase generator has two main windings: 1. A three-phase AC winding 2. Another winding carrying DC. In most cases the rotor has the DC winding and the stator the AC …

Read More »

Iron Losses in AC Generator

Iron Losses in AC Generators

An iron core onto which the coils are wound improves the voltage output by increasing the flux density, but causes two undesirable effects: eddy-current losses and hysteresis losses. Eddy-Current Losses Since iron is an electrical conductor, the rotation of an iron core within a magnetic field generates an EMF in …

Read More »

AC Synchronous Generator: Working Principle, Types

A synchronous generator is a machine that produces AC voltage when its shaft is rotated. A synchronous generator is called synchronous because the generated voltage waveform it produces is synchronized with the rotation of the generator. Synchronous Generator Basics A synchronous generator is an ac generator in which the output …

Read More »

Three-Phase AC Generator Working

3-phase revolving-armature generator

There are two basic types of 3-phase generators (alternating-current generators): (1) the revolving-armature type (Figure 1) and (2) the revolving-field type (Figure 2).  The 3-phase revolving-armature generator rotates the three single-phase windings, located 120 mechanical degrees apart on the rotor assembly, around the inside of a fixed or stationary electromagnetic …

Read More »

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 …

Read More »

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}} & {} & …

Read More »

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, …

Read More »

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 …

Read More »


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 …

Read More »

Stepper Motor Types and Working

Stepper motors are close relatives of brushless DC motors. The brushless DC motor is used where continuous motion is required, such as a fan or a disk drive. The stepper motor, on the other hand, is designed to move infinite increments (steps) in either direction and to keep track of …

Read More »

Electric Machine Efficiency and Losses

Regardless of which type of electric machine is chosen for a particular job, efficiency is important for several reasons. First, and perhaps most obvious, a less efficient machine will cost more to operate. Second, the losses in the machine are converted to heat, which raises the operating temperature of the …

Read More »