• 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

    Basic Electrical

    What is a Voltage Source? | DC and AC Voltage Sources Explained

    • Categories Basic Electrical, Battery, Electronics
    dc voltage source

    Definition: Any device that produces voltage output continuously is known as a voltage source.

    There are two types of voltage sources,

    1. Direct voltage source
    2. Alternating voltage source

    Table of Contents

    • Direct voltage source
    • Alternating Voltage Source
    • Constant Voltage Source
      • Related Articles

    Direct voltage source

    As the name implies, a direct voltage source continuously produces direct voltage output. Typical examples are batteries and DC generators. 

    An important characteristic of a direct voltage source is that it maintains the same polarity of the output voltage i.e. positive and negative terminals remain the same. 

    When load resistance RL, is connected across such a source, current flows from positive terminal to negative terminal via the load. This current is the conventional current however the flow of electrons are in the opposite direction.

    dc voltage source
    DC voltage source

    This is called direct current because it has just one direction. The current has one direction as the source maintains the same polarity of output voltage. The opposition to load current inside the DC source is known as internal resistance Ri. 

    Equivalent circuit of DC source
    Equivalent circuit of DC source

    The equivalent circuit of a DC source is the generated emf Eg, in series with internal resistance Ri , of the source as shown in the figure.

    Load Current I = Eg / ( RL + Ri )

    Terminal Voltage V = Eg – I Ri or I RL

    Alternating Voltage Source

    A device which produces alternating voltage output continuously is known as alternating voltage source. Example of ac voltage source is an Alternator.

    An important characteristic of alternating voltage source is that it periodically reverses the polarity of the output voltage. When load impedance ZL is connected across such a source, current flows through the circuit that periodically reverses in direction. This is called alternating current.

    AC voltage source
    AC voltage source

    The opposition to load current inside the AC source called its internal impedance Zi . The equivalent circuit of an AC source is the generated e.m.f. Eg (rms) in series with internal impedance Zi of the source as shown in the figure above.

    The equivalent circuit of an AC source can be drawn as below.

    Equivalent circuit of AC source
    Equivalent circuit of AC source

    From the images, it is clear that,

    Load Current I (rms) = Eg / ( ZL + Zi )

    Terminal Voltage V = (Eg – I Zi ) or I ZL

    (Vector difference since AC quantities are vector quantities)

    Constant Voltage Source

    The term constant voltage source refers to a voltage source whose internal impedance is very low in comparison to the load impedance.

    In such a case, the output voltage nearly remains the same when load current changes.

    Related Articles

    • 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)…

    • Current
      What Are Current, Resistance and Voltage?

      Voltage, current, and resistance are three properties that are fundamental to almost everything you will…

    • Effects of Voltage and Frequency Variation on Transformers
      Effects of Voltage and Frequency Variation on Transformers

      The effects of voltage and frequency variation on the transformer is discussed in this article.…

    • Voltage 2Bconrol 2Bin 2Bpowr 2Bsystem
      Why Voltage Control is Important?

        In a modern power system, electrical energy from the generating station is delivered to…

    • surge
      Voltage Surge in Power System

      What is Voltage Surge or Transient Voltage? The sudden rise in voltage for a very…

    • dc motor voltage and power equations
      Voltage and Power Equations of DC Motor | Condition of Maximum Power

      In this post, we will look at the voltage and power equation of a dc motor and…

    • Share:
    Tesla Edison
    Tesla Edison

    Tesla is an Electrical Engineer, Physicist and an Inventor in making. He is a good writer and author of many courses and articles published in this site.

    Previous post

    Roles of a Commercial Electrician
    December 20, 2021

    Next post

    Concept of Electric Charge and Current
    December 22, 2021

    You may also like

    dc bias characteristics of capacitor
    What is a capacitor’s DC bias characteristic?
    22 March, 2023
    passive components
    Understanding Passive Components in Electrical Engineering
    3 March, 2023
    used oscilloscope buying guide (1)
    Buying a Used Oscilloscope: A Guide to Help You Decide
    28 February, 2023

    Leave A Reply Cancel reply

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

    Search Here

    From Blog

    maxresdefault
    An Introduction to the Arduino for Beginners
    11Apr2016
    external-characteristic-of-seperately-excited-dc-generator
    Characteristics of Separately Excited DC Generators
    07Aug2014
    Construction of High Voltage Current Transformer
    Basic Types of Current Transformers
    26Oct2015
    back up protection
    Primary and Back-up Protection in Power System
    19Jun2016

    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