pysong
Forum Regular
Join Date: 2.2.2023
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Posted: 5.17.2023 2:19:46
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Rotary slip ring connectors — what are they used for?
Rotary slip ring connectors are important components in various applications like multi-axis robots in industry 4.0, wind turbines for sustainable green energy, machine tools, medical systems, and more.To get more news about slip ring contacts, you can visit grandslipring.com official website.
This FAQ considers how slip ring connectors differ from commutators, and how mercury-wetted, pancake, and wireless slip ring connectors work, their capabilities, and reviews applications where they are used to transfer power, control circuits, transmit analog or digital signals, or liquids and gases.
Slip rings, split rings, and commutators
Slip and split rings are both designed to maintain electric circuit continuity between fixed and rotary sections in a mechanical system. The difference is that a slip ring can transmit signals and or power between the sections, while a split ring is used to reverse the direction of current flow as the rotary section spins.
A split ring is literally split into at least two pieces; in some designs, there are multiple splits in the ring. When split into two and used in a commutator, the split ring is alternately connected to the poles of a motor reversing polarity as the motor spins. The split ring is connected to the motor poles with brushes. The combination of the split ring and brushes is called a commutator.
Slip rings are also called rotary joints, rotary electrical interfaces, rotating connectors, collectors, and swivels. They are available in various geometries and constructions, like a pancake and through bore designs (Figure 1).
Slip ring construction
The most common slip ring constructions are based on mechanical connections with brushes on a stator that slide against conducting rings on a rotor. The brushes can be made from various conductive materials, and the selection of material is based on several factors, including signal bandwidth, the amount of power to be transmitted, quality of the signal or power to be transmitted, speed of rotation, environmental factors, and reliability requirements. The moving mechanical contacts often require monitoring and frequent maintenance. Environmental factors are often the most limiting factor in the performance of mechanical slip rings. In addition, the sliding contacts can generate vibrations and electrical noise that can reduce the quality of the transmitted signals. That can be especially troublesome in applications requiring real-time control, like robotics. Several other slip ring designs are available to meet the demands of specific applications.Mercury-wetted slip rings
Mercury-wetted slip rings replace the sliding brush contacts with a pool of liquid mercury bonded to the contacts. The mercury maintains a low friction and efficient electrical connection between the two sides of the slip ring. Mercury solidifies at about -40°C, which can limit the use of this design. In addition, mercury is a toxic substance and poses safety challenges.
Wireless slip rings
Wireless slip rings transmit signals and power using magnetic coils on either side of the slip ring and produce contactless and frictionless transfers. These designs are more suited for harsh environments requiring less maintenance than conventional moving mechanical contacts. Wireless slip rings can transmit higher frequency signals with higher quality and less interference, but they are limited in the amount of power they can transmit. If power coupling is important, a traditional moving contact slip ring can usually transmit several orders of magnitude more power in the same size solution.
Fiber optic slip rings
Fiber optic rotary joint (FORJ) is a type of contactless slip ring designed for data transmission only. FORJs are particularly useful in high EMI environments and typically use 850 or 1550 nm infrared transmission of analog or digital signals and can data rates of 50 Gbps or higher. FORJs can be challenging to implement and suffer from high signal attenuation if not precisely aligned in angular and axial directions. Misalignments can also result in rotational signal fluctuations. Because of their sensitivity, using FORJs in industrial environments can be especially challenging and demand high levels of protection, increasing installed costs.
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