Slip rings for data and power transmission

Slip rings for data and power transmission

The world of industry and electromechanics is always in motion. More precisely, in rotary motion (rotating consumers). Wind turbines, medical technology, crane technology, stage technology, video cameras, screens, data-driven automation, data transmission and robotics – standstill is the death of efficiency and innovation. Therefore, reliable, maintenance-free and loss-free power and signal transmission between the individual stationary and rotating components is required. The ever faster and endlessly rotating data transmission of control signals, video signals and measurement data is becoming increasingly important. In addition to the standard current transmission, rotary transmission of fluids (e.g. hydraulic fluid or oil), gases and compressed air complement the classic slip rings.

Since numerous mechanical components are always in rotation, which makes fixed power transmission or data transmission via cables impossible, slip rings are indispensable and almost maintenance-free and invisible electromechanical components. At the same time, slip ring assemblies and their sliding contacts are the heart of every automation system and machine, which, thanks to the brush (sliding contact), enables contactless power and signal transmission between stationary and moving components, or components rotating against each other, e.g. of video signals, Ethernet signals / Profinet, KOAX, HD-SDI, fibre optic cables and field buses. For this purpose, the slip ring assemblies must be manufactured according to your personal and industry-specific requirements and from the best materials, which enable fast, low-wear and loss-free transmission of data and power under a wide range of conditions and temperatures. Just like our slip ring assemblies and rotary unions from RotarX. As a manufacturer of slip rings, our focus is on the highest contact quality of the silver-to-silver and gold-to-gold sliding contacts and maximum life expectancy, while at the same time requiring the least amount of maintenance.

In our shop you can choose from simple slip rings for power transmission or hybrid combinations that transmit media or signals or data in addition to power.

Classic application areas for the wireless transmission of power, or additionally of data, liquid media and control signals are:

  • Rotating and slewing movements of a crane
  • Filling systems
  • Circular scraper (sewage treatment plants)
  • Revolving doors
  • Dump trucks
  • 4K video image transmission
  • Radar systems
  • Computer networks
  • Support arm lights
  • Wind turbines
  • Packaging machines
  • Stage technology such as lifting platforms or rides such as roller coasters

Slip rings are therefore installed in numerous electrical machines and industrial systems in all sectors, whose components cannot be connected to fixed power supplies by cable due to their constant rotation. Thanks to their high material quality, robust construction, intelligent design and maintenance-free, high-quality contacts, rotarX slip rings and rotary joints guarantee highly reliable, low-wear data and power transmission between rotating components and stationary machines. Or between two components rotating against each other. The of our slip ring bodies is based on fibre brushes and fibre brushes as sliding contacts, which can also be combined with rotary unions for media such as water, hydraulic oil, compressed air and gases as required.

Hybrid slip rings & rotary unions for additional signal transmission of Ethernet, fieldbuses & Co.

In the past, slip rings primarily ensured power transmission and rotary feed-through. With the growing importance of the IoT (Internet of Things) and Industry 4.0, however, the need for hybrid slip rings that enable loss-free and fast transmission of optical fibres, field buses such as 100 BaseT, Interbus, Profibus, Canbus and Powerlink, Ethernet signals as well as control and video signals, KOAX, USB and HD-SDI is growing. Thanks to technical progress, more and more sensors are also being used in industrial applications and components, which have to collect enormous amounts of data and make it available to connected devices, making data-driven automation in Industry 4.0 feasible in the first place. Here, the electrical and hybrid slip ring is used as a connection, i.e. as a physical contacting method for current and data transfers between rotating and stationary components. This is also needed, for example, for computer interfaces, strain gauges, measuring systems, resolvers and temperature control. The hybrid combination of power and signal transmission is used, among other things, for servo motors and pulses or the control of FU motors.

In addition to over 7,000 standard solutions, slip rings from the manufacturer rotarX are also available as a modular system that can be individually adapted to your area of application.

At the same time, you benefit from many other advantages:

  • Connectors can be fitted according to customer requirements
  • freely selectable cable length
  • individual cable entry
  • Customised special designs even for small quantities
  • EMI shielding of analogue, digital and HF signals possible
  • Operating temperature up to 300°C possible
  • Various fastening options
  • Suitable for high voltage, control voltage or low voltage
  • Low-wear and maintenance-free continuous operation with optimum dynamics
  • Silver-silver and gold-gold contacts
  • Open and encapsulated slip rings

Advantages of slip rings for data transmission:

  • Suitable for up to 1 GBit/s (Ethernet)
  • Stable performance and no loss of data packets
  • CAT5E, CAT6 or CAT7E cable
  • low noise
  • Working temperature: -30°C to +80°C

Slip ring bodies – modular system & standard series

All our slip ring bodies are available as standardised or modularised versions. This means that our slip rings can be completely customised to suit you and your business or intended use. If you have special customised requirements, we will be happy to advise you on the most suitable recommendation for your specification. Please feel free to contact us. This is the only way we can design the technically and economically ideal slip ring system solution for each customer. Combine different transmission technologies and contacting transmissions of electrical power, signals and data.

Our engineers will advise you on the ideal sliding contacts and brush, as these vary according to the current, voltage, rotation speed, bandwidth, impedance and operating temperature of the components.

These factors & functions should be considered by engineers for slip rings

You can also obtain slip rings from the manufacturer rotarX as a standard variant. However, slip ring systems are usually individually designed solutions, depending on the respective area of application from robotics to wind power. There are numerous factors that should be taken into account here:

  • HF shielding
  • Processing of the signal mix
  • Contact resistance
  • Matching of high frequency impedances
  • Operating temperature
  • Product life cycle
  • Weather resistance and environmental conditions
  • Available space in the installation room

Modern technology now lives not only from a reliable power supply, but also from the connection to the Ethernet. The broadband requirement therefore faces the challenge of electromagnetic interference (EMI) more than ever. Ethernet signals and power must be passed on in combination via slip rings from stationary to rotating components (and vice versa). These react sensitively to external electromagnetic interference. Here our experts have the know-how of special HF design techniques to shield motor applications from EMI. This prevents data integrity from being compromised. We pass on these techniques for so-called RF shielding and physical isolation to you as a product and knowledge transfer. Here it is of enormous importance that the shielding is done via a separate channel in the slip ring, which completes the electrical connection between rotor and stator shielding. In this way, the shielded energy benefits from optimal earthing via this separate channel.

In addition, data integrity is improved by reducing electrical brush noise. This is an accurate measure of the contact resistance of each channel as the slip ring rotates. You will find exact details on the respective product page. Overall, you benefit from very low electrical noise due to our fibre brush technology. This is also reflected in the measured quality of the data signal transmission, which is given in lost packets per million.

Last but not least, industrial designers and engineers need to know the environmental characteristics of the installation space and the machine. These have a great impact on the sliding contacts. A precise knowledge of the protection classes as well as shock and vibration, which affect the sealing requirements, as well as the type of sliding contact technology and the position of the contacts is a basic requirement here.

You should pay attention to these criteria when buying a slip ring:

  • Transmission technology– how is current and / or signal transmitted from the stationary component to a rotating component?
  • Connectivity– how is the electrical connection created on stationary and rotating components?
  • Operating speed– level of speed (rpm) of the unit?
  • Housing- What materials and seals ensure the proper and reliable operation of the slip ring in the installation space?

These are the questions you should ask yourself:

  • How many electrical channels are needed?
  • What is the voltage and current of the channels?
  • Which data protocol is used?
  • Is the slip ring connected to the system or component via plugs or lead wires?
  • Does earthing have to take place?
  • How is the slip ring fastened?
  • Which IP protection class and seals (e.g. to protect against contamination) are necessary in the respective operating environment?
  • What atmospheric conditions and media (water, dirt, mud) must be taken into account?
  • Does the slip ring rotate quickly and does the direction of rotation change during operation?
  • How high is the load on the individual channels?

All in all, a multitude of aspects and factors have to be taken into account when designing a slip ring. That’s why you should make sure that a manufacturer makes its interest in improvement, innovation and new technologies clear and integrates them into its own processes – just like rotarX. After all, technology is advancing rapidly and the necessary transmission speeds and data volumes are growing exponentially. Therefore, you should additionally ensure that the slip ring can forward and process analogue and digital signals.

In addition, the slip ring should fit optimally into the design of your installation and the specific installation space. A mix of standard parts with configurable options such as transmission technology, connectivity, packing size and housing and individual designs for a fusion of slip ring and rotating union in one housing are the best approach here. A manufacturer and supplier who offers both types here in a kind of construction kit optimises the purchasing process and time-to-market – just like rotarX.