Common Mode Chokes

A common mode (CM) choke is an electrical filter that blocks high-frequency noise on power and data lines while allowing the desired DC or low-frequency signal to pass undisturbed. Common mode noise is typically generated by unwanted radio signals, unshielded electronics, inverters, and motors. Left unfiltered, this noise causes interference problems across electrical and electronic circuits.

Browse through RS Australia’s over a thousand collection of choke filters, including DC, 3-phase, RF, and power line choke types.

Key Benefits & Uses of Common Mode Chokes

Common mode chokes can be used to help prevent electromagnetic interference and radio frequency interference. By using these chokes, you can access the following benefits:

• Stop EMI & RFI Before it Causes Problems: A common mode choke filter blocks high-frequency EMI and RFI from radio signals, inverters and motors before they reach sensitive components. It prevents malfunctions and signal degradation on the power supply and data lines.
• Protect Your Equipment Without Disrupting Your Signal: A common mode choke filter suppresses noise on both lines simultaneously while letting the desired differential signal pass cleanly through, with no loss of normal signal quality.
• Available for AC & DC Power Lines: From a DC common mode choke for battery-powered systems to a common mode power line choke for mains AC circuits, RS Australia stocks options for switch-mode supplies, inverters, and rectifiers.
• Wide Inductance & Frequency Range: RS Australia stocks common mode chokes across a range of inductance values with high attenuation over a broad frequency range.

Shop Our Range of Common Mode Chokes

RS Australia stocks common mode chokes across a range of formats and configurations. Our product listing covers the most commonly specified types for industrial, commercial, and PCB-level applications:

DC Common Mode Chokes

A DC common mode choke is designed to filter common mode noise specifically on DC power lines, offering low DC resistance and strong common mode impedance for effective EMC suppression. These chokes are suitable for DC power supply lines, battery-powered devices, EV charging circuits, and industrial DC control panels.

3-Phase Common Mode Chokes

A 3-phase common mode choke uses a three-winding design to filter noise across all three phases simultaneously in a single compact unit. These are commonly specified for variable frequency drives, frequency converters, charge stations, and UPS power supply systems in industrial power environments.

Common Mode RF Chokes

A common mode RF choke is optimised for high-frequency noise suppression on signal and data lines, featuring high common mode impedance at elevated frequencies within a compact surface-mount package. These chokes are ideal for high-speed digital interfaces such as USB and IEEE applications, PCB designs, and communication systems requiring clean RF signal paths.

Power Line Chokes (Common Mode Power Line Choke)

A common mode power line choke filters noise on single-phase AC mains lines and is used in switch-mode power supplies, phase-angle control circuits, and EMI input filter stages. RS Australia stocks power line choke options with rated currents from 0.3A to 10A and resonance frequencies from 100kHz to 3MHz.

3-Line Common Mode Chokes

A 3-line common mode choke filters all three conductors of a three-conductor system within a single package, including 3-phase and neutral line configurations. These compact units suit frequency converters, charge stations, and UPS systems where space efficiency and multi-line filtering are both required.

How to Choose the Right Common Mode Choke

Matching the right common mode choke to your application comes down to these important parameters:

• Choke Type: Use a DC common mode choke for DC lines, a 3-phase common mode choke for motor and VFD applications, a common mode RF choke for high-frequency signal lines, and a power line choke for AC mains circuits.
• Impedance: Higher impedance delivers better noise rejection at the target frequency. Check the datasheet for impedance versus frequency curves before selecting.
• Frequency Range: Match the choke's frequency response to the noise band you need to suppress.
• Current Rating: Always choose a choke rated above your maximum operating current to prevent saturation and performance loss.
• Mounting Type: Through-hole suits lower-volume builds and prototyping, while SMD suits automated PCB assembly.
• Number of Lines: Choose a standard two-line choke for single-phase circuits or a 3-line common mode choke for three-conductor systems.

Common Industry Applications for Common Mode Chokes

Common mode chokes are used wherever electrical noise threatens equipment performance or signal integrity. Some of their applications include:

• Industrial Systems: Filtering noise from motor drives, VFDs, and industrial power supplies to maintain operational stability and reduce EMI from switching equipment.
• Data Storage and Computing: Suppressing EMI in servers, storage arrays, and data centres where signal integrity is critical.
• Telecommunications: Noise filtering on Ethernet, DSL, and signal lines to maintain data integrity across the communication infrastructure.
• Professional Audio: Removing common mode interference from balanced audio lines, mixing consoles, and broadcast equipment.
• Digital Video Cameras: Filtering power and signal lines in broadcast and security camera equipment.
• Consumer Electronics: Noise suppression in switched-mode power supplies, LED drivers, and home appliances, often alongside EMI power line filters.
• EV and Automotive: DC common mode choke applications in onboard chargers, CAN bus systems, and EV powertrain circuits.

Your Trusted Common Mode Choke Supplier in Australia

RS Australia stocks a comprehensive range of common mode chokes, common mode choke filters, and power line chokes from leading manufacturers, including Wurth Elektronik, TDK, Murata, Bourns, and KEMET. Browse our range of EMI filters, power line filters, and shielding cages for complementary components.

All products are genuine and supported by technical support to help you specify the right product for your application. Order online with ease and enjoy fast delivery across Australia. For delivery details, visit our Delivery page.