A slip ring is a device that makes an electrical connection between a stationary structure and a rotating structure. Slip rings are utilized in systems that rely on the transmission of power/data while also maintaining rotation. These systems include but are not limited to electrical generators for AC systems, packaging machinery, alternators, wind turbines, and cable reels. Also commonly referred to as rotating electrical connectors, swivels, rotary electrical interfaces, electrical rotary joints, and collectors, slip rings often simplify system operation and improve mechanical performance. A slip ring is usually comprised of a stationary graphite or metal contact that brushes on the outer diameter of a rotating metal ring. The current is conducted through the stationary brush to the metal ring to make the connection as the ring turns.
Slip rings come in a wide range of sizes and can be designed in a number of configurations (such as drum, platter, or pancake) to suit a variety of applications including rotating tanks, radio telescopes, aerodrome beacons, and power shovels. The devices do the same for electrical power and signal that rotary unions do for fluid media and can be employed in a rotary union to work concurrently with the rotary joint to send data as well as power to and from the rotating machinery in conjunction with the media the rotary union offers. Slip rings are known for reliability and having long service lives while meeting exacting requirements in even the most demanding environments and applications.
Slip Rings - United Equipment Accessories, Inc.
Silver Plated vs. Solid Coin
Results provided by: United Equipment Accessories, Inc.
Test performed by: Kyle Riegel, Design Engineer
When used with silver graphite brushes, UEA’s Silver Plated Rings perform with similar resistance to Solid Coin Silver Rings with a significant potential savings for the customer.
|Silver Plated Ring
||Solid Coin Silver Ring
METHOD OF TESTING:
In the test, the resistance was calculated by measuring the potential difference across two brush/ring pairings and dividing by the known current (2 amps). The formula is Resistance=Voltage/Current. It should be noted that UEA silver brush on silver ring configurations have a significantly low resistance of about 5 milliohms per circuit. In comparison, 300 feet of Cat5e cable has about 14 ohms in resistance.
When comparing the material costs, a coin silver ring is about 7x that of plated silver ring. Including labor, the savings is over $20/circuit. Although the savings are significant, there are limitations to plating. Silver plated rings will not maintain functionality as long as solid coin silver rings. Therefore, the specific application can dictate whether it is
necessary to use solid silver or plated rings. In the UEA tests, the plated rings were tested well over 5.5 million revolutions and had yet to lose any functionality. In many applications like cranes, which typically rotate 1 to 2 million times in their lifetime, 5.5 million revolutions is more than sufficient.