Call us: 1.603.894.6100
cet@cettechnology.com
High Quality, Standard and Custom Magnetics Since 1987
CET TechnologyCET TechnologyCET TechnologyCET Technology
  • Home
  • Electrical Transformers
    • Toroidal Transformers
    • Step Down Transformers
    • Planar Transformers
    • Power Transformers
    • Current Sense Transformers
    • Switching Transformers
    • Flyback Transformers
    • Encapsulated Transformers
    • High Voltage Transformers
    • Audio Transformers
    • Class 2 Transformers
    • View All Transformers
  • Inductors
    • Toroidal Inductors
    • Common Mode Choke
    • Drum / Bobbin Core Inductors
    • Air Core Coil Inductors
    • PFC Inductors
    • View All Inductors
  • DC-DC Converters
  • Power Supplies
  • Custom Designs
  • Blog
  • Contact
    • RFQ

The Basics of Common Mode Choke Windings

    Home Electrical Technology The Basics of Common Mode Choke Windings
    NextPrevious

    The Basics of Common Mode Choke Windings

    By Michelle Farnum | Electrical Technology, Inductors | Comments are Closed | 3 December, 2016 | 0

    Common Mode Choke windings

    The impedance of an inductor is proportional to its inductance and the frequency of the signal passing through it. Inductors, therefore, can act like low-pass filters, that is they allow low-frequency signals to pass through them, while they block higher frequency signals. A common mode choke inductor is a special type of filter with two inductor windings on the same core. In order to understand common mode choke windings, it is important to first understand what “common mode” means.

    Normal Mode:  During normal operation of any circuit (such as a switch-mode power supply) connected to the AC Mains, AC current flows in through the AC Line and out through the AC neutral.  This is called Normal Mode Current (or Differential Mode Current.)

    Common Mode: There are other noise currents generated in most circuits that tend to be higher in frequency. These currents can be conducted out of the AC Mains in the form of noise.  This is called Common Mode Noise. The current flows out on both the AC Line and AC neutral, hence the term Common Mode. It is this noise that a Common Mode Choke seeks to suppress.

    How do common mode choke windings work?

    A common mode choke includes a magnetic core and two windings, making it a four-terminal device. The two common mode choke windings have the same number of turns and are wound in opposite directions in a mirror configuration.

    In this configuration, normal mode current flows into the circuit through one of the windings, and out through the other. The direction of current in each common mode choke windings combined with the mirror winding configuration means the flux generated by each winding cancels out the flux generated by the other winding. Thus the common mode choke presents a very low impedance to normal mode currents.

    For common-mode noise, however, the flux generated by the current in each winding is additive, causing the choke to present a very high impedance to common mode currents.

    As stated above, the impedance of the common mode choke is proportional to the frequency of the current. So determining the required inductance of the choke depends on the lowest frequency of common-mode noise the designer is trying to suppress.

    The wire for a common mode choke must be larger enough in diameter to handle the Normal Mode current without overheating.

    Contact us at CET Technology to discuss and discover the benefits of common mode choke inductors.

    No tags.

    Michelle Farnum

    More posts by Michelle Farnum

    Related Post

    • Custom Chokes

      By sps | Comments are Closed

      Here at CET, we do custom transformer and inductor solutions every day. One such part was a high current custom choke desired by a customer of ours. The design of this part actually went through a…

    • What is an Inductor?

      By Michelle Farnum | Comments are Closed

      What is an inductor, its purpose, and how does it work? Inductors are an electrical component made essentially of a coil of wire, often wound around a magnetic core. From our experts, here are some facts to…

    • Switched Mode Power Supply

      By sps | Comments are Closed

      A switched mode power supply (SMPS) is a more modern and efficient take on the older power supplies known as linear supplies.   LINEAR SUPPLIES Linear supplies would often take in line voltage, transform this…

    • High Voltage Transformer Design

      By sps | Comments are Closed

      When it comes to high voltage transformer design, it can be a bit tricky. When you’re trying to target a particular voltage one needs to account for things such as DCR losses in the windings. This is…

    • Excessive Inventory For Sale!

      By sps | Comments are Closed

      A super quiet EP13 size flyback transformer. Primary inductance is 4.31mH +/- 10%. Switching frequency is 60 KHz minimum. The input is rated at 120V. There are 2 outputs rated at 2.5V/600mA and an aux…

    • Forward Converter Transformer Design

      By sps | Comments are Closed

      The forward converter does appear similar to the flyback transformer, but it is actually very different. A forward converter transformer transfers its energy instantly (transformer action), unlike the flyback which stores and then releases that…

    • AC to DC Conversion: Voltage Transformation

      By sps | Comments are Closed

      Most everything we use of convenience and need these days is electrically powered. Most often we have access to a source of voltage at one, or maybe two particular values. Unfortunately in many cases, the…

    • Transformer Design Equation

      By sps | Comments are Closed

      When it comes to transformer design, there is an equation most of us are familiar with. This transformer equation is known as the “transformer design equation”. This transformer equation is applicable for inputs that are…

    NextPrevious

    Latest News from CET

    Custom Chokes

    Here at CET, we do custom transformer and inductor solutions every day. One such part was a high current custom choke desired by a customer of ours. The design of this part actually went through a…

     

    What is an Inductor?

    What is an inductor, its purpose, and how does it work? Inductors are an electrical component made essentially of a coil of wire, often wound around a magnetic core. From our experts, here are some facts to…

     

    CET Technology… Building Relationships One Component at a Time.

    • Home
    • Electrical Transformers
      • Toroidal Transformers
      • Step Down Transformers
      • Planar Transformers
      • Power Transformers
      • Current Sense Transformers
      • Switching Transformers
      • Flyback Transformers
      • Encapsulated Transformers
      • High Voltage Transformers
      • Audio Transformers
      • Class 2 Transformers
      • View All Transformers
    • Inductors
      • Toroidal Inductors
      • Common Mode Choke
      • Drum / Bobbin Core Inductors
      • Air Core Coil Inductors
      • PFC Inductors
      • View All Inductors
    • DC-DC Converters
    • Power Supplies
    • Custom Designs
    • Blog
    • Contact
      • RFQ
    Copyright © 2016 CET Technology - 27 Roulston Rd, Windham NH 03087 - Phone: (603) 894-6100 - Fax: (603) 894-6161 - cet@cettechnology.com
    • Home
    • Electrical Transformers
      • Toroidal Transformers
      • Step Down Transformers
      • Planar Transformers
      • Power Transformers
      • Current Sense Transformers
      • Switching Transformers
      • Flyback Transformers
      • Encapsulated Transformers
      • High Voltage Transformers
      • Audio Transformers
      • Class 2 Transformers
      • View All Transformers
    • Inductors
      • Toroidal Inductors
      • Common Mode Choke
      • Drum / Bobbin Core Inductors
      • Air Core Coil Inductors
      • PFC Inductors
      • View All Inductors
    • DC-DC Converters
    • Power Supplies
    • Custom Designs
    • Blog
    • Contact
      • RFQ
    CET Technology