• 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]
RegisterLogin
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

    Single Phase Motors

    Shaded Pole Induction Motors – Working and Construction

    • Categories Single Phase Motors, Electrical Machines
    Construction of Shaded Pole Induction Motor
    Shaded pole induction motor Operation working construction
    Shaded pole motor is a split-phase type single phase induction motor. The shaded pole motor is very popular for ratings below 0.05 HP (~ 40 W) because of its extremely simple construction. 
     
    Shaded pole motorShaded%2Bpole%2Bmotor%2BschematicIt has salient poles on the stator excited by a single-phase supply and a squirrel cage rotor. A portion of each pole is surrounded by a short-circuited turn of a copper strip called shading coil. 

    A shaded pole motor and its schematic diagram are shown in the figures above.

    Table of Contents

    • Construction of Shaded Pole Induction Motor
      • Stator
      • Rotor
    • Working of Shaded Pole Induction Motor
    • Characteristics of Shaded Pole Motors
      • Related Articles

    Construction of Shaded Pole Induction Motor

    A shaded pole motor may be of 2 poles or 4 poles. Here we are considering a 2 pole shaded pole motor. The figures in this article also show a 2 pole motor.

    Construction of Shaded Pole Induction Motor
    Construction of Shaded Pole Induction Motor

    Stator

    Shaded%2Bpole%2Bmotor%2BconstructionThe stator has salient poles. Usually, 2 to 4 poles are used. Each of the poles has its own exciting coil.

    A part of each pole is wrapped by a copper coil. The copper coil forms a closed-loop across each pole. This loop is known as the shading coil.

    The poles are laminated. A slot is cut across the lamination of the pole. The slot is approximately one-third distance from the edge of the pole. The short-circuited copper coil described above is placed in this slot. So we can call this part as the shaded part and other parts of the pole as unshaded part.

    Selecting a 2 poled stator gives a synchronous speed of 3000 rpm while a 4 poled stator speed will be 1500rpm for 50Hz supply.

    Rotor

    The rotor of shaded pole induction motors is the Squirrel Cage type rotor. The rotor bars are provided with a 60-degree skew. This is to obtain an optimum starting torque and for limiting the torque dip during the run-up.
     
    DisassembledShadedPoleMotor LG
    Parts of a Shaded Pole Induction Motor

    Airgap length between stator and rotor is of the order 0.25 to 0.5 mm. Too short air-gap may result in starting-torque variations due to rotor slotting.

    The shaded pole induction motor has no commutator, brushes, collector rings, contactors, capacitors or moving switch parts, so it is relatively cheaper, simpler and extremely rugged in construction and reliable. The absence of a centrifugal switch eliminates the possibility of motor failure due to faulty centrifugal switch mechanisms.

    Working of Shaded Pole Induction Motor

    The operation of the motor can be understood by referring to the figure which shows one pole of the motor with a shading coil. Considering a cycle of alternating current (fig 1) applied to the stator winding we will explain the working of shaded pole motor.

    Working%2Bof%2BShaded%2BPole%2Binduction%2Bmotor

    During the portion OA

    During the portion OA of the alternating-current cycle [Fig 1], the flux begins to increase and an e.m.f. is induced in the shading coil. The resulting current in the shading coil will be in such a direction (Lenz’s law) so as to oppose the change in flux.

    Thus the flux in the shaded portion of the pole is weakened while that in the unshaded portion is strengthened as shown in figure 2.

    During the portion AB

    During the portion AB of the alternating-current cycle, the flux has reached the almost maximum value and is not changing. Consequently, the flux distribution across the pole is uniform [See Fig 3] since no current is flowing in the shading coil. 

    During the portion BC

    As the flux decreases (portion BC of the alternating current cycle), the current is induced in the shading coil so as to oppose the decrease in current. Thus the flux in the shaded portion of the pole is strengthened while that in the unshaded portion is weakened as shown in Fig 4.

    The effect of the shading coil is to cause the field flux to shift across the pole face from the unshaded to the shaded portion. This shifting flux is like a rotating weak field moving in the direction from the unshaded portion to the shaded portion of the pole.

    The rotor is of the squirrel-cage type and is under the influence of this moving field. Consequently, a small starting torque is developed. As soon as this torque starts to revolve the rotor, additional torque is produced by single-phase induction-motor action. The motor accelerates to a speed slightly below the synchronous speed and runs as a single-phase induction motor.

    Characteristics of Shaded Pole Motors

    Some of the important characteristics of shaded pole induction motors are given below. The details of the characteristics of the shaded pole motor will be discussed later. 
    1. The salient features of this motor are extremely simple construction and absence of centrifugal switch.
    2. Since starting torque, efficiency and power factor are very low, these motors are only suitable for low power applications e.g., to drive: (a) small fans (b) toys (c) hair driers (d) desk fans, etc.

    Related Articles

    • Construction of Three Phase Induction Motor
      Three Phase Induction Motors - Construction

      A three phase induction motor has two main parts stator  rotor. The rotor is separated…

    • universal motor construction
      Construction of Universal Motors

      A universal motor is one of the single-phase motors that can be operated on either…

    • single-phase-Induction
      Single Phase Induction Motor - Working Principle and Construction

      Single-phase motors are the most familiar of all-electric motors because they are extensively used in…

    • Capacitor-start-induction-run
      Split Phase and Capacitor Start Induction Motors

      Before reading Split Phase and Capacitor Start Induction Motors, please read the previous article, Why…

    • working of three phase induction motor
      Three Phase Induction Motor: Construction and Working Principle

      The three-phase induction motors are the most widely used electric motors in the industry. They…

    • single phase ac motors
      AC Single Phase Motors

      Single phase motors are the most familiar of all electric motors because they are extensively…

    • Share:
    author avatar
    Electrical Engineer

    Previous post

    Animated Video - Working of Moving Coil Instruments
    February 17, 2016

    Next post

    Why Motor Fails? Most Common Causes
    February 22, 2016

    You may also like

    transformer-winding
    Transformer Windings: Types and Design
    22 November, 2022
    Photo by Sven Daniel on Unsplash
    What is CNC Machining? | Definition, Processes, Components & More
    3 November, 2022
    Generator on Load
    DC Generator Problems and Solution: EMF Equation of DC Generator
    27 September, 2022

      1 Comment

    1. proxy
      February 23, 2019
      Reply

      Nice pictures. Easy to learn. Thankyou

    Leave A Reply Cancel reply

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

    Search Here

    From Blog

    Substation Bus Configurations
    Substation Bus Configuration / Scheme: The Definitive Guide
    03Oct2019
    Thin film resistors
    Applications & Functions of Thin Film Resistors
    12Jan2023
    Effects of Voltage and Frequency Variation on Transformers
    Effects of Voltage and Frequency Variation on Transformers
    12Aug2014
    Three Phase Transformer Connections
    Three Phase Transformer Interconnections
    13Aug2014

    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?

    Not a member yet? Register now

    Register a new account

    Are you a member? Login now