Slip ring 101: The basics

In electrical engineering terms, a slip ring is 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.

Merriam-Webster.com Dictionary

How does a slip ring 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.

Vector illustration of slip ring construction

Where are slip rings used?

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

Defence: Rotating tank turrets, radar and surveillance systems

Medical: Microscopes, scanning equipment

Renewable energy: Wind turbines

What are some common uses for slip rings?

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

  • Rotary electrical interfaces
  • Rotating electrical connectors
  • Collectors
  • Swivels
  • Electrical rotary joints 

As well as these common alternatives, slip rings can be confused with a commutator; the difference is that slip rings are continuous whereas commutators are segmented. They are 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 slip ring testers are available for this unique set of test requirements.