Author
Home > Engineering > What is the Difference Between DC Motor and DC Generator?

Guilherme Mazui

•4 minutes to read

What is the Difference Between DC Motor and DC Generator?

🆚 Go to Comparative Table 🆚

The main difference between a DC motor and a DC generator lies in the conversion mechanism. Here are the key differences between the two:

  • Function: A DC motor converts electrical energy into mechanical energy, while a DC generator converts mechanical energy into electrical energy.
  • Input/Output: A DC motor has a DC current as an input and provides mechanical output, whereas a DC generator has a mechanical energy input and provides DC current as an output.
  • Commutation: In DC motors, commutators are used for changing the magnetic field polarity, while in DC generators, commutators are used to cancel the polarization effect.
  • Electromotive Force (EMF): In a DC motor, the EMF is utilized by the coil and is useful for rotating the axle. In a DC generator, the EMF produced around the coil is transmitted to the load and used by them.
  • EMF vs Terminal Voltage: In a DC motor, the EMF in the armature is less than its terminal voltage (Eb < V), while in a DC generator, the produced EMF is more than its terminal voltage (Eg > V).
  • ** generated EMF/Back EMF**: For a DC motor, the back EMF is given by the formula: Eb = V - IaRa, where V is the terminal voltage, Ia is the armature current, and Ra is the armature resistance. For a DC generator, the generated EMF is more than the terminal voltage.

Despite these differences, both DC motors and DC generators share a similar mechanical structure and can be considered as essentially the same thing with different subjective uses.

On this page
  • What is the Difference Between DC Motor and DC Generator?
  • Comparative Table: DC Motor vs DC Generator

    • Comparative Table: DC Motor vs DC Generator

    Here is a table comparing the differences between a DC motor and a DC generator:

    Characteristic DC Motor DC Generator
    Definition A DC motor is a device that converts electrical energy into mechanical energy. A DC generator is a device that converts mechanical energy into electrical energy.
    Role in Energy Conversion DC motors consume electricity to produce mechanical energy. DC generators produce electricity when supplied with mechanical energy.
    Direction of Current The current flow in a DC motor is from the supply to the armature winding. The current flow in a DC generator is from the armature winding to the supply.
    Fleming's Rule DC motors follow Fleming's left-hand rule. DC generators follow Fleming's right-hand rule.
    Principle The working principle of a DC motor is based on the interaction between two magnetic fields, which causes the rotor to turn due to the force experienced by a current-carrying conductor in a magnetic field. The working principle of a DC generator is based on electromagnetic induction, where the spinning of the coil with an external force causes the creation of a voltage and current in the coil.

    In summary, a DC motor is a device that uses electrical energy to create mechanical energy, while a DC generator is a device that produces electrical energy when given mechanical energy. The direction of current flow and the rules followed by these devices differ, with DC motors following Fleming's left-hand rule and DC generators following Fleming's right-hand rule.

    Read more:

    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.