• Home
  • Courses
  • Machines
    • Transformer
    • AC Motors
      • Induction Motor
      • Synchronous Motor
    • DC Motor
    • DC Generator
  • Power System
    • Circuit Breaker
    • Switchgear
    • Substation
    • Control System
    • Measurement
  • Electronics
  • Blog
  • Contact
    • Contact Us
    • Privacy Policy
Have any question?
[email protected]
Login
StudyElectrical.Com
  • Home
  • Courses
  • Machines
    • Transformer
    • AC Motors
      • Induction Motor
      • Synchronous Motor
    • DC Motor
    • DC Generator
  • Power System
    • Circuit Breaker
    • Switchgear
    • Substation
    • Control System
    • Measurement
  • Electronics
  • Blog
  • Contact
    • Contact Us
    • Privacy Policy

    DC Motor

    Armature Reaction in DC Motors

    • Categories DC Motor, Electrical Machines, Synchronous Motor, Three Phase Induction Motor
    adcmotor

    Armature reaction also occurs in a DC motor just like armature reaction in DC Generator.

    This is expected because when current flows through the armature conductors of a DC motor, it produces flux (armature flux) which lets on the flux produced by the main poles.

    For a motor with the same polarity and direction of rotation as is for the generator, the direction of armature reaction field is reversed.

    In a generator, the armature current flows in the direction of the induced e.m.f. (i.e. generated e.m.f. Eg) whereas in a motor, the armature current flows against the induced e.m.f. (i.e. back e.m.f. Eb).

    Therefore, it should be expected that for the same direction of rotation and field polarity, the armature flux of the motor will be in the opposite direction to that of the generator.

    Hence instead of the main flux being distorted in the direction of rotation as in a generator, it is distorted opposite to the direction of rotation.

    We can conclude that:Armature reaction in a DC generator weakens the flux at leading pole tips and strengthens the flux at trailing pole tips while the armature reaction in a DC motor produces the opposite effect.

    Armature reaction in dc motor

    In case of a DC generator, with brushes along G.N.A. and no commutating poles used, the brushes must be shifted in the direction of rotation (forward lead) for satisfactory commutation.

    However, in the case of a DC motor, the brushes are given a negative lead i.e., they are shifted against the direction of rotation.

    With no commutating poles used, the brushes are given a forward lead in a DC generator and backward lead in a DC motor.

    By using commutating poles (compoles), a DC machine can be operated with fixed brush positions for all conditions of load.

    Since commutating poles windings carry the armature current, then, when a machine changes from a generator to motor (with consequent reversal of current), the polarities of commutating poles must be of opposite sign.

    Therefore, in a d.c. motor, the commutating poles must have the same polarity as the main poles directly back of them. This is the opposite of the corresponding relation in a DC generator.

    Related Articles

    • armature-reaction-dc-generator
      Armature Reaction in DC Generator

      To understand the concept of armature reaction in DC generator, please go through the previous…

    • DC-Series-Motor
      Speed Control Of DC Series Motors

      Although a far greater percentage of electric motors in service are ac motors, the dc motor…

    • SPEED-CONTROL-OF-DC-SHUNT-MOTOR
      Speed Control of DC Shunt Motors

      The different methods of speed control in DC shunt motors are explained below, Flux Control…

    • effects of armature reaction in alternator
      Armature Reaction in Alternator

      Armature reaction in alternator is the effect of armature flux on the field flux (i.…

    • Testing a DC Motor
      Testing of DC Machines (DC Motor and DC Generator)

      There are several tests that are conducted for testing a dc machine (generator or motor)…

    • dc motor characteristics
      Characteristics of DC Series Motor

      In this post, we will look into the characteristics of a DC series motor. A…

    • Share:
    author avatar
    Electrical Engineer

    Previous post

    5 Types of DC Motors | Series, Shunt, and Compound
    December 30, 2014

    Next post

    Working of Air Circuit Breakers
    December 30, 2014

    You may also like

    separately excited dc generator characteristics
    Beginner’s Guide to Separately Excited DC Generator
    8 May, 2023
    DC Machines Construction MCQ
    DC Machines Construction MCQ Objective Question Quiz with Answer
    24 February, 2023
    transformer-winding
    Transformer Windings: Types and Design
    22 November, 2022

    Leave A Reply Cancel reply

    Your email address will not be published. Required fields are marked *

    Search Here

    From Blog

    video how single phase motor works
    Video – How Single Phase Induction Motor Works?
    10Feb2016
    Time-domain-vs-frequency-domain
    Time Domain Analysis vs Frequency Domain Analysis
    09May2023
    circuit breaker rating
    Circuit Breaker Ratings
    24Jun2014
    A hypothetical capacitor
    Capacitors and Capacitance – Working, Unit, Types and Specification
    27Oct2019

    Categories

    • Alternator
    • Arduino
    • Basic Electrical
    • Battery
    • Books
    • Cables
    • Capacitor
    • Career
    • Circuit Breaker
    • Control System
    • DC Generator
    • DC Generator MCQ
    • DC Generator Solved Problems
    • DC Motor
    • DC Motor MCQ
    • Drives
    • Electric Vehicles
    • Electrical Circuits
    • Electrical Machines
    • Electrical Relays
    • Electrical Safety
    • Electronics
    • Embedded System
    • Exams
    • Generation
    • Guest Post
    • HVDC
    • Instrumentation
    • Interview Questions
    • Locomotives
    • MCQ
    • Measurement
    • Microcontroller
    • Objective Questions
    • PCB
    • PLC
    • Power System
    • Problems and Solution
    • Projects
    • Resistor
    • Signals and Systems
    • Single Phase Motors
    • Substation
    • Switchgear
    • Synchronous Motor
    • Three Phase Induction Motor
    • Transformer
    • Transmission Line
    • Uncategorized

    Copyright © 2021 Study Electrical, Inc.

    © StudyElectrical.Com 2021

    Login with your site account

    Lost your password?

    x
    x