The application of precision conductive slip ring in large rotary support rotating antenna

     1 Overview
    Conductive slip ring, also known as collector ring, rotary knuckle, adapter, etc., is a relative rotating object to transmit energy, control, communication and other signal devices, the use of sliding slip ring and brush sliding contact to achieve signal transmission, is a variety of precision rotating devices, inertial guidance devices and other equipment, one of the key components, especially 360 degrees of unrestricted non-stop rotation, while meeting the signal transmission, can be widely used in aerospace, the Military, equipment automation, large rotating mechanism, wind power generation and some other equipment. The precision conductive slip ring component used in the large rotary support rotating antenna of my unit is the power supply of the device within the rotating part of our rotating antenna and the pivot of the antenna control signal transmission, which is one of the three core components of the rotating antenna. The rotary section performance is stable, with high conductivity, small contact resistance, high magnetic resistance, good impedance matching, high precision, low noise characteristics.  
    2 Conductive slip ring structure principle
    The precision conductive slip ring is composed of a slip ring body, brushes, fixed bracket, bearings and other auxiliary components. Precision conductive slip ring is the use of conductive ring sliding contact, electrostatic coupling or electromagnetic coupling, in the fixed stand rotating parts and rolling or sliding components between the transmission of electrical energy, control, communication and other signals of precision transmission device. The slip ring body is usually mounted in the centre of the rotation axis of the rotating device and consists of a rotating device part and a fixed device part. The upper rotating part is connected to the rotating part of the rotating device and follows its rotation, so it is called the "rotor": the fixed part is connected to the base of the rotating device to support the fixed part, so it is called the "stator". The electrically conductive slip ring as a whole relies on elastic contact lap technology, good rolling lap technology, precise material selection, tight sealing protection level and clever structural design to form a stable and reliable rotating transmission system. The signal is transmitted to the upper rotating part through sliding contact, solving problems such as line entanglement due to the absence of conductive slip rings, without affecting the detection and control of equipment status.
    3 Rotating antenna conductive slip ring of the main technical indicators
    Slip ring's main technical indicators are: insulation, contact resistance, dynamic contact resistance, protection level, transient break resistance, anti-electromagnetic interference performance, friction torque, etc.
    3.1 Slip ring insulation Slip ring consists of many ring channels, its insulation performance to be good, the distance between the ring will lead to the overall size of the slip ring is too long, the distance is too small will lead to insulation, low voltage, generally take 1.5 ~ 3mm is appropriate, according to the requirements of the rotating antenna on the slip ring ring channel insulation resistance should be greater than 100MΩ, voltage 500V and not be broken; its resistance to electrical strength can reach: power ring 2000MΩ, communication, control ring 500MΩ requirements.
    3.2 Slip ring contact resistance sliding ring groove and brush contact to be reliable and moderate, and the two materials selected to match, when the equipment rotation, sliding surface line speed is brush line speed dozens to thousands of times, relatively easy to wear brush; but when the brush material hardness is much higher than the ring groove hardness, in the ring groove will appear the same wear, especially in the high temperature environment, more likely to produce excessive wear, the reducing the service life of the equipment and causing inconvenience to maintenance. The pressure of the brush on the ring groove also affects the size of the contact resistance, but too much pressure, more than the friction torque, the contact part wears more, reducing the service life of the equipment. The greater the contact resistance of the slip ring, the worse the information transmission effect, the greater the contact pressure drop, the higher the temperature, the easier to melt the slip ring, I turn the antenna slip ring made of brass, the surface is coated with multiple layers of precious metals, with good electrical conductivity, thermal conductivity, anti-oxidation, anti-sulphuration, wear resistance, anti-melt welding and other properties, the design is "II" type, easy to The brushes are in symmetrical double contact with the ring groove, using the elastic pressure of the brushes and the sliding contact of the ring groove to transmit signals. The power ring used for the rotating antenna slip ring is 11MΩ and 35MΩ respectively; the control and communication ring is 210MΩ.
    3.3 slip ring dynamic contact resistance slip ring surface finish, slip ring rotation speed, ring channel diameter, etc. will affect the dynamic impedance of the slip ring, the smaller the dynamic contact resistance, the more stable the operation of the equipment, rotating antenna slip ring using the power ring respectively: 5MΩ, 10MΩ; control, communication ring 15MΩ requirements.
    3.4 Slip ring protection level Slip ring requires full shielding and sealing, shielding material selection 1J79, slip ring protection level: IP54; where 63A and 16A slip ring grounding must be internally riveted in the stator and rotor to ensure grounding continuity. A 50mm2 earthing point is required on the outside of the stator and rotor. To ensure good contact, this point must be flat, without paint or insulating treatment.
    3.5 Resistance of slip rings to transient breakage Transient breakage is an important indicator to characterise the performance of precision conductive slip rings and generally requires a compliance period of less than 10ms.
    3.6 slip ring anti-electromagnetic interference performance in my unit of large rotating devices, precision conductive slip ring is in the high current, high power, high-frequency conditions of work, the device itself is a dense line, space is small within the sealed device, so there is mutual inductance between the signals, mutual capacitance phenomenon, easy to generate electrostatic induction, magnetic induction, my equipment line output high-frequency 3MHz-30MHz, power up to 750kW of energy. Power up to 750kW of energy, the use of the approach to the protection of the signal for protection, and the interference source itself plus shielding to weaken the interference, and shielding line shielding layer grounding. When the interference source voltage is higher, higher frequency, it is appropriate to use electromagnetic shielding, available conductive materials to do shielding; rotating antenna slip ring electrical noise performance, power ring respectively: 10, 20 (1kHz, uV/mA); control, communication ring 30 (1kHz, uV/mA) requirements.
   Compared with other precision conductive slip ring, rotating antenna conductive slip ring work in high frequency, high power, high voltage state, its own size, high technical requirements, its maintenance level requirements are high, so regular index test is the basic guarantee of equipment in good condition.

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