Slip ring
Encyclopedia
A slip ring is a method of making an electrical
connection through a rotating assembly. Slip rings, also called rotary electrical interfaces, rotating electrical connectors, collectors, swivels, or electrical rotary joints, are commonly found in electric motors
, electrical generator
s for AC
systems and alternator
s and in packaging machinery, cable reels, and wind turbine
s. They can be used on any rotating object to transfer power, control circuits, or analog or digital signals including data such as those found on aerodrome beacon
s, rotating tank
s, power shovels, radio telescope
s or heliostat
s.
A slip ring is a rotary coupling used to transfer electric current from a stationary unit to a rotating unit. Either the brushes or the rings are stationary and the other component rotates.
This system is similar to the brush
es and commutator
, found in many types of DC motor
s. While commutators are segmented, slip rings are continuous, and the terms are not interchangeable. Rotary transformer
s are often used instead of slip rings in high speed or low friction environments.
Mercury
-wetted slip rings, noted for their low resistance and stable connection use a different principle which replaces the sliding brush contact with a pool of liquid metal molecularly bonded to the contacts. During rotation the liquid metal maintains the electrical connection between the stationary and rotating contacts. However, the use of mercury poses safety concerns, as it is a toxic substance. If a slip ring application involves food manufacturing or processing, pharmaceutical equipment, or any other use where contamination could be a serious threat, the choice should be precious metal
contacts. Leakage of the mercury and the resultant contamination could be extremely serious.
A pancake slip ring has the conductors arranged on a flat disk as concentric rings centered on the rotating shaft. This configuration has greater weight and volume for the same circuits, greater capacitance and crosstalk, greater brush wear and more readily collects wear debris on its vertical axis. However, a pancake offers reduced axial length for the number of circuits, and so may be appropriate in some applications.
Slip rings are made in various sizes; one device made for theatrical stage lighting had 100 conductors. The slip ring allow for unlimited rotations of the connected object, whereas a slack cable can only be twisted a very few times before it will fail.
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
connection through a rotating assembly. Slip rings, also called rotary electrical interfaces, rotating electrical connectors, collectors, swivels, or electrical rotary joints, are commonly found in electric motors
Slip ring motor
A slip ring motor or wound-rotor motor is a type of induction motor. The rotor windings are connected to a slip ring, connected to external resistances, which allows controlling the speed/torque characteristic of the motor...
, electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
s for AC
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
systems and alternator
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...
s and in packaging machinery, cable reels, and wind turbine
Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...
s. They can be used on any rotating object to transfer power, control circuits, or analog or digital signals including data such as those found on aerodrome beacon
Aerodrome beacon
An aerodrome beacon or rotating beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night....
s, rotating tank
Rotating tank
A rotating tank is a device used for fluid dynamics experiments. Typically cylinders filled with water on a rotating platform, the tanks can be used in various ways to simulate the atmosphere or ocean....
s, power shovels, radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
s or heliostat
Heliostat
A heliostat is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating for the sun's apparent motions in the sky. The target may be a physical object, distant from the heliostat, or a direction in space...
s.
A slip ring is a rotary coupling used to transfer electric current from a stationary unit to a rotating unit. Either the brushes or the rings are stationary and the other component rotates.
This system is similar to the brush
Brush (electric)
A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators.-Etymology:...
es and commutator
Commutator (electric)
A commutator is a rotary electrical switch in certain types of electric motors or electrical generators that periodically reverses the current direction between the rotor and the external circuit. In a motor, it applies power to the best location on the rotor, and in a generator, picks off power...
, found in many types of DC motor
DC motor
A DC motor is an electric motor that runs on direct current electricity.-Brush:The brushed DC electric motor generates torque directly from DC power supplied to the motor by using internal commutation, stationary magnets , and rotating electrical magnets.Like all electric motors or generators,...
s. While commutators are segmented, slip rings are continuous, and the terms are not interchangeable. Rotary transformer
Rotary transformer
A rotary transformer is a specialized transformer used to couple electrical signals between two parts which rotate in relation to each other....
s are often used instead of slip rings in high speed or low friction environments.
Mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
-wetted slip rings, noted for their low resistance and stable connection use a different principle which replaces the sliding brush contact with a pool of liquid metal molecularly bonded to the contacts. During rotation the liquid metal maintains the electrical connection between the stationary and rotating contacts. However, the use of mercury poses safety concerns, as it is a toxic substance. If a slip ring application involves food manufacturing or processing, pharmaceutical equipment, or any other use where contamination could be a serious threat, the choice should be precious metal
Precious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals...
contacts. Leakage of the mercury and the resultant contamination could be extremely serious.
A pancake slip ring has the conductors arranged on a flat disk as concentric rings centered on the rotating shaft. This configuration has greater weight and volume for the same circuits, greater capacitance and crosstalk, greater brush wear and more readily collects wear debris on its vertical axis. However, a pancake offers reduced axial length for the number of circuits, and so may be appropriate in some applications.
Slip rings are made in various sizes; one device made for theatrical stage lighting had 100 conductors. The slip ring allow for unlimited rotations of the connected object, whereas a slack cable can only be twisted a very few times before it will fail.