This document provides an overview of DC machines including generators and motors. It discusses the working principles, construction details, types of DC motors including shunt, series and compound motors. It covers key concepts such as EMF equation, back EMF, torque equation and characteristics of DC motors. It also discusses starters for DC shunt motors and speed control methods including flux and armature voltage control. Finally, it briefly mentions some industrial applications of DC motors.
2. Unit 2 Introduction to DC Machines
DC Generator:- A machine which converts
Mechanical Energy into Electrical energy is
called as “Generator”
DC
Generator
Mechanical
Energy
Electrical
Energy
13. Construction Details(Parts) of DC
Generator and DC Motor
• Yoke
• Armature
• Pole Core and Pole shoe
• Field winding
• Armature winding
• Commutator
• Brushes
• Bearings
34. 3. DC Compound Motor charact.
Electrical Charact. Mechanical Charact.
35. Necessity of Starter
• Starter is not used to start the motor.
• Motor Can Start without Starter also.
• Then What is the necessity of Starter?
• We know that, V= Eb + IaRa but If N=0, then Eb=0
• Then We get, V= 0 + IaRa
• Therefore Ia = V/Ra. If rated Volt is 230V DC and Ra=
1Ω (Assume)
• Then Ia= 230/1 = 230 Amp. If Such a very high curren
t flows through Armature at the time of start it may bur
n armature wdg, may damage brushes etc.
• Therefore, Starter is used to limit the very high sta
rting current taken by the motor at the time of start
.