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A Definitive Guide To Toroidal Chokes

Toroidal Chokes

Toroidal chokes, also known as common mode chokes, are magnetic inductors that act as a filter to block the high-frequency noise & interference from power supply lines and allow the desired direct current (DC) to pass through. They are designed using an insulated wire wound around a magnetic core. They have a high initial permeability & high saturated magnetic strength as compared to ferrites. So, they have greater insertion loss and cannot be magnetised to saturation during strong current interference.

In this blog post, we’re going to walk you through the basics of toroidal chokes that will help you make a better choice while choosing them for your applications. 

What are the uses of Toroidal Chokes?

Toroidal Chokes are used to reduce or eliminate electromagnetic interference (EMI) in industrial equipment that requires a fixed and constant flow of current with no obstructions. This noise is usually radiated from different sources, such as inverters, motors, unwanted radio signals, uncovered electronics, etc. If the noise is not suppressed using a filter, it creates interference problems in electrical circuits.

For instance, the chokes help to suppress noise & current fluctuations in applications with a high current flow, like AC/DC power supply lines and video signal lines. They have the ability to filter multiple lines of current at the same time using a common magnetic core.

Types of Toroidal Chokes

Toroidal chokes are available in two types— Radio Frequency (RF) chokes & Audio Frequency (AF) chokes. The difference between the two chokes lies mainly in their core’s composition. 

RF chokes are designed with a magnetic core made of powdered iron or ferrous micro beads to filter high-frequency noise. On the other hand, AF chokes are designed with a solid magnetic core of iron. 

How do Toroidal Chokes work?

Toroidal chokes use a low impedance coil to suppress high-frequency current in an electrical circuit. They have several identical coils in which the current flows in opposite directions. 

In differential mode, the current travels in a line and in one direction from the source to the load, and then in the opposite direction on the return line that completes the circuit. Owing to this, the magnetic flux is cancelled out so that the field allows the normal mode signals to pass through. 

Whereas, in common mode, the current travels in a group of lines in the same direction so that the combined magnetic flux can create an opposing field to block the unwanted noise signals. 

Common Applications

  • Switching regulators & switch mode power supplies (SMPS)
  • LED lights
  • Medical equipment
  • Robotic equipment 
  • Audio/visual signal equipment 
  • Oil & gas control system
  • Train signal system
  • HVAC system
  • Industrial tools
  • Conveyors & elevators
  • Inverters
  • Radio signalling devices

How can you select a Toroidal Choke?

If you want to select the right toroidal choke for your application, you must first consider any specific requirements or limitations of your device. Usually, larger chokes are better able to filter lower frequencies than smaller chokes, which makes them ideal for equipment that needs accurate noise filtering, such as AC/DC outlets. 

Besides, there are 3 major factors that can be considered while selecting toroidal chokes. 

  1. Impedance: Analyse how much noise needs filtration. 
  2. Frequency: Measure the frequency range of the noise that needs filtration.  
  3. Current: Determine the amount of current that the choke must handle.

The choke must also be able to maintain the quality of the signal. Its impedance and transmission line should be compatible, so that it leaves no impact on the quality of the signal after the insertion takes place. 

Find the best Toroidal Chokes at Alisha Coils & Transformers

Toroidal chokes are the right choice for you to ensure the highest common mode impedance for your electronics over a widest frequency range. They are ideal for applications that need a high DC current and for switch mode power supplies. 

Alisha Coils & Transformers (A Division of Cosmo Ferrites) manufactures the toroidal chokes in many sizes to suit a variety of applications. They understand the electrical needs of each customer and then provide a customised solution for their products. 

For more information on common mode chokes, you can contact their team.