How do slip rings work?

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This article gives an overview of what slip rings are, what they’re for and how they work. Think of it as a 101 overview guide!

In electrical engineering terms, slip rings are a method of making an electrical connection through a rotating assembly.  It enables the transmission of power and data signals from a stationary to a rotating structure.

“A slip ring is one of two or more continuous conducting rings from which brushes take or to which they deliver current in a generator or motor.” Dictionary.

How do slip rings work?

Slip rings solve the problem of how to safely run electricity to a continuously rotating part of an assembled product.

Constructed of two main parts, a metal ring is generally the rotating element, whilst a brush contact is usually fixed.  The outer part (usually the brush) is called the Stator because it is stationary, and the internal part (the ring) is called the Rotor, as it rotates.

As the rings rotate, an electrical current is conducted through the brushes, making a continuous connection.


Where are they used?

A broad range of rotating objects use slip rings to transfer electrical signals from a stationary to a moving part.  Common applications are:

Defence: Rotating tank turrets, radar and surveillance systems

Medical: Microscopes, scanning equipment

Renewable energy: Wind turbines

How do slip rings work - military applications How do slip rings work - medical application How do slip rings work - wind energy application

What are some alternative names?

Slip rings have many other commonly used names, which are listed below.   There are probably many more terms out there – please get in touch if we’ve missed any common names from this list.

  • Rotary electrical interfaces
  • Rotating electrical connectors
  • Collector rings
  • Electrical rotary joints
  • Schleifring (also the name of a major slip ring manufacturer)

They can also often be confused with a commutator.  The difference between the two is that slip rings are continuous whereas commutators are segmented. Commutators are commonly used on DC motors and generators.

How is the quality of slip rings checked during manufacture?

Most slip ring manufacturers will carry out QC checks on 100% of goods prior to despatch.  These standard QC tests include continuity, insulation resistance, dielectric strength, torque and rotational tests to ensure the slip rings are fit for purpose in the end product.

Specialist test systems are available for this unique set of test requirements.  For more background information on slip rings and their applications, we’ve got several more useful posts in our blog. To learn about our purpose-designed tester, visit the SRT product page.