Slip ring
The slip ring is an electromechanical assembly and, together with the so-called brush, forms a sliding contact . It enables electrical power or signals to be transmitted between components rotating against one another .
General
The most important materials used in slip rings include brass, bronze, stainless steel, precious metals and carbon, and sintered materials are also possible. While the metallic slip rings are primarily suitable for high current transmission, slip rings based on carbon offer advantages when transmitting small electrical powers. They are less wear-resistant and more resilient. In addition to the general requirements such as low wear and tear and contact quality, the specific application conditions and required transmission capacities play a major role in the design.
Applications
Energy Technology
In the field of electrical power engineering, slip rings are used in many rotating electrical machines such as slip ring motors or in separately excited synchronous generators . The spectrum ranges up to electrical currents of a few kA , with several brushes connected in parallel to increase the current carrying capacity . In the field of electrical installation , slip rings are used in cable drums , which are installed in fire brigade vehicles under the name "Rapids attack".
In electroplating , sliding contacts are used with currents of up to 20 kA when chrome-plating or galvanizing surfaces. Extreme conditions prevail with these high transmission capacities: the baths are strongly acidic or basic and the reactions take place at elevated temperatures.
In wind power plants, slip rings, apart from the rotating electrical machine, also serve as lightning protection . The rotating parts are electrically connected to the fixed earthing system via slip rings . Without slip rings, a flashover or arcing would occur in the area of the mechanical bearings in the event of a lightning strike in the exposed rotor blades . The consequence would be bearing damage due to undesired welded connections in machine elements that move with respect to one another.
Slip rings are also used in space travel , for example in actuators for solar cell booms. Furthermore, slip rings can be found in electromagnetic clutches. These supply the coil with current and thus enable switching.
Signal transmission
Complex slip ring systems with a large number of poles are often used for signal transmission. These systems are also known as "slip ring assemblies" or "slip ring assemblies".
Slip ring systems are used for signal and energy transmission in radar systems with rotating antennas or in the field of medical technology for devices such as computer tomography . Convenience applications include "telephone cable detanglers" that are attached to the RJ plug-in connection on landline telephones as an additional connection piece between the telephone receiver and the spiral telephone cord . This prevents the conventional spiral telephone cable to the telephone receiver from becoming undesirably knotted or twisted when the receiver is used repeatedly.
Alternatives
All slip ring systems have the problem of permanently reliable electrical contact, since all sliding contacts wear out due to the principle of abrasion.
Alternatives that almost avoid wear and tear include: a. the rotary transformer , a special type of transformer. These can be used for signal transmission in a contactless manner, for example with the rotating head drum of video recorders. Or to a lesser extent for power transmission, but in contrast to sliding contacts, they are limited to AC voltage . In addition, the magnetic coupling in the rotary transformer is deteriorated by the inevitable gap in the magnetic circuit between the rotating and stationary parts.
Wireless systems can also be used for signal transmission, for example by radio or also by infrared .
literature
- A. Senner: Electrical engineering . 4th edition. Europe teaching aids, 1965.
- Gregor D. Häberle, Heinz O. Häberle: Transformers and electrical machines in power engineering systems . 2nd Edition. Europa-Lehrmittel, 1990, ISBN 3-8085-5002-3 .
Individual evidence
- ↑ REQUIREMENTS FOR fire fighting vehicles and their equipment in the federal state of Salzburg ( Memento of the original from April 5, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Lightning protection for wind turbines. Retrieved December 3, 2014 .
