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Electrical Slip Ring, All You Need to Know

The tendency to get a data connection at a good pace, particularly within the mechanization industry, needs slip rings. In which these slip rings should be able to enhance the transmission of power and increase data connection.

In this article, you will get to know what slip rings are and how they operate in the process of signal and power transmission?

What is a slip ring?

Electrical Slip Ring structure

 A slip ring is an electromechanical device that helps transmit electric power, analog signals, and digital signals. And these are transmitted from stationary segments of the machine to a rotating part of the machine. It provides a good electrical connection to control circuits and for transferring influential electrical signals and data. Slip rings comprise five (5) components that work together to give a fast and flawless connection for electric and rotating devices. The components of an electrical slip ring are; housing or casing,  rotor, a stationary or fixed brush, a conductor ring, and ball bearings.

Some alternative names used for Slip Ring are; rotating electrical collectors, electrical rotary interfaces, transmission rings, rotating electrical connectors, swivels, or electrical rotary joints. And these slip rings or rotating electrical connectors are typically found in numerous motors systems, cable reels, packaging machinery, AC electrical generators system, etc.

Various slip ring products are based on the industries’ components and requirements depending on the slip ring technologies. The common slip rings include Pancake slip rings, Ethernet Slip Rings, Waterproof slip rings, Mercury slip rings, Pneumatic slip rings, Fiber optic slip rings. Other types of slip rings are Miniature slip rings, Capsule slip rings, Wireless slip rings, and USB slip rings.

How does a Slip Ring work?

The slip rings comprise two significant elements: brush contact (stationary graphite or phosphor bronze) and metal rings. Also, the number of the brushes and rings is decided based on the application and design of the machine. The graphite in brush contact is a cheap alternative, but the phosphor bronze is a better conductor and has more wear life.

The brush rubs on the external diameter of a rotating metal ring based on the rotations per minute (RPM). Then the brushes are stabilized with the rotating rings. And the brushes retain connection with the ring by pressure from the springs in this arrangement. The metal rings are formulated conductive metals like silver and brass. Its shaft is mounted but has its center shaft insulated. Plastic or nylon are used in insulating the rings from each other.

The electric current is being conducted through the brushes as the ring rotates. Hence, it generates a continual connection between the rotating system, I.e., the rings, and the fixed system, I.e., the brushes. In low friction or high-speed environment, rotary transformers are used in place of slip rings.

Why do we use slip rings in motors?

electrical AC motor

Typically, the conventional use of slip rings is the transmission of power in any application that involves a rotating platform or base. They are also applicable to transmitting analog signals and digital signals from strain gauges or temperature sensors. And you can use them for the transmission of data through Ethernet or some other bus network. In a wound rotor motor, Slip rings are used for inserting resistance into the windings of a rotor. In this case, slip rings are not used for the transmission of power.

In the bullet points, we use slip rings for;

  • Transmission of power.
  • Transmission of analog signals and digital signals
  • Transmission of data.
  • Inserting resistance into a rotor’s windings.

What is the difference between slip ring and split ring?

A split ring is a mobile device made of copper and used to reverse the current’s polarity. The connection of the brushes and the split ring is called the commutator. The split ring is used in the DC motor for obtaining the oscillating input voltage.

The following are the differences between a slip ring and a split ring;

  1. The slip ring is used to transmit power from the stationary and rotary parts of the machine. In contrast, the split ring is used for changing a current’s polarity.
  2. The slip ring is used in an AC machine, while the split ring is used in a DC machine.
  3. The slip ring is in a continuous ring structure, while as the name of the split ring implies, it splits into two or more parts.

Summary

Before selecting a ring, you need to ask a few questions to guide you through your choice-making. To make a practical choice, you need first to ask yourself, what type of application do you want to use? Is it domestic or industrial? You may select an electrical slip ring suitable for you based on the type of bandwidth, power speed, or signal conditions for your application.

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