This document provides an overview of synchronous machines, including: - Synchronous machines can be generators or motors, and are known for their constant speed operation. Electromechanical energy conversion occurs through flux and mechanical motion. - The main components are a stator, rotor, field windings on the rotor, and armature windings on the stator. The rotor rotates inside the stator separated by an air gap. - Armature windings are 3-phase and distributed around the stator core in slots. The field winding is energized by direct current to produce a rotating magnetic field. This induces a 3-phase voltage in the armature windings based on their position.

1. HALDIA INSTITUTE OF TECHNOLOGY
SYNCHRONOUS MACHINE
BY:-Mitesh kumar
Roll no. :- 13/EI/26
Univesity Roll no. :- 10300513026
Applied Electronics & Instrumentation Engg.

2. Introduction
•A synchronous machine is a most important type of electric
machine.
•Synchronous Machine used at generating stations are known as
Synchronous Generators or Alternators
•Synchronous motors are widely used in Industries and are well
known for their const. speed operation
•Electromechanical energy conversion occurs whenever a change in
flux is associated with mechanical motion

3. Construction of Synchronous Machine
It consists of:
 Stator
 Rotor
 Field Windings (On rotor)
 Armature Windings (On Stator)

4. Diagram

5.  It is a stationary member
 It is the cylindrical portion inside which the rotor rotates
 An air gap is provided between the stator and the rotor
 Armature winding are 3 phased and are housed in the slots cut in the
stator
 It consists of cast iron stator frame, a cylindrical laminated , a
cylindrical laminated and uniformly slotted core

6.  Rotor is the rotating part of the machine
 Can be classified as: (a) Cylindrical Rotor and (b) Salient Pole rotor
 Large salient-pole rotors are made of laminated poles retaining the winding
under the pole head.

7.  Armature windings connected are 3-phase and are either star or delta
connected
 The windings are 120 degrees apart and normally use distributed windings

8. The 3-phase armature winding is distributed in the slots along the
armature air gap periphery
For example: Consider that we have 18 slots, 2-pole 3-phase winding..
Hence we have 9 slots/per pole as shown figure

9.  The winding diagram of phase ‘a’ can be shown as:
 Similarly, phase ‘b’ and phase ‘c’ are distributed in same manner

10.  The field winding of a synchronous machine is always energized with
direct current
 Under steady state condition, the field or exciting current is given
Ir = Vf/Rf
Vf = Direct voltage applied to the field winding
Rf= Field winding Resistance

11. The mmf-phase graph can be drawn as:
 This implies that per phase emf is getting divided in each phase.
 When all the 3-phase are connected then mmf-phase graph for each
phase is displaced by 120 degrees

12.  Mostly all the synchronous machines use Distributed winding
 Attempt is made to use all the slots available under a pole for the
winding which makes the nature of the induced e.m.f. moe sinusoidal
 Consider a sync. Machine with 3-phase winding,
Slots, s= 18 slots
Poles=2
slots per pole, g= s/p= 9
slots/pole/phase= g/3 = 3

13. Thank you