Want superior connection, or an ordinary slip ring? The choice is yours. These Frequently Asked Questions explain the benefits of "Rotating Electrical Connectors".

Why are rotating electrical connectors superior to slip rings?
Rotating electrical connectors use a unique design principle unlike the sliding, brush contact of a slip ring. The connection is made through a pool of liquid metal molecularly bonded to the contact, which provides a low resistance, stable connection. When there is rotation the fluid maintains the electrical connection between the contacts without any wear. The following are among the many reasons why rotating electrical connectors are superior to slip rings. First, unlike a slip ring, rotating electrical connectors produce near zero electrical noise due to their unique design. Second, resistance through the rotating contact is less than one milliohm, which is much lower than the resistance of a slipring. Third, rotating electrical connector do not degrade the signal over time, which does happen with slip rings. Fourth, slip rings require maintenance and rotating electrical connectors are maintenance free. Fifth, rotating electrical connectors are more compact and cost far less than slip rings of equal capacity. (top)
Are rotating electrical connectors made of durable materials?
Yes. The rotating electrical connector is ruggedly constructed utilizing a sealed ball bearing in a black anodized aluminum body.The electrical connections are silver plated brass or copper for low resistance. The white mounting bushing on both ends of the larger rotating electrical is insulating plastic potted with epoxy. Rotating electrical connectors are very durable as well as being compact. (top)
Can rotating electrical connectors be used for low voltage signal, data, thermocouple and strain gauge circuits?
Yes. In addition to normal current and voltage uses, rotating electrical connectors are ideally suited to low voltage/low amperage current and signal transmission. Unlike standard brush slip rings, rotating electrical connector use liquid metal as the conductor. This produces an extremely low noise signal transmission similar to the signal transmitted through a solid wire. This makes rotating electrical connectors superior to brush slip rings for signal and data transmission. The signal quality does not degrade and no maintenance of the rotating electrical connector is required. (top)
How do I select the right rotating electrical connector for my application?
The number of conductors, voltage, amperage, and RPM will determine which model of rotating electrical connector needed. First, decide the number of conductors needed. Next, consult the specification page to determine if a Coaxial or Modular unit will meet your amperage, voltage, and RPM requirements. Please note: Even though the larger rotating electrical connectors are rated for 30 amps they work equally well for signal applications (top)
How are rotating electrical connector mounted?
Rotating electrical connectors are designed for mounting to the end of the rotating axis either in a vertical or horizontal attitude. The mounting method depends upon the rotating electrical model. The larger rotating electrical connectors typically are mounted into a hollow shaft or collar on the end of the rotating device either by the plastic bushing or the body. The rotating electrical connector can be held in place with a setscrew or a slotted clamp system. The smaller rotating electrical connectors plug into the electrical receptacle and use this both as the mounting and electrical connection. These receptacles are knurled and designed to be press fitted into a hole on the end of the rotating device. Eccentricity of the mounting should be less than .005” TIR. The preferable end of the rotating electrical connector to mount is with the body end rotating. Both ends of the rotating electrical connector should not be rigidly mounted; one end needs to float free. If needed, a floating torque arm may be used to prevent the stationary end from rotating. Please note that rotating electrical connectors are not designed to support any load. Please see Literature page for downloadable "Application Information" for more details. (top)
Can rotating electrical connectors be used upsidedown?
No, rotating electrical connectors do have a top and a bottom. An arrow on the side of each unit specifies the top. A vertical mounting would position the rotating electrical connector with the arrow pointing up. Rotating electrical connectors can be mounted at vertical or any angle between vertical and 90 horizontal. This allows for nearly any mounting attitude that would be required. They cannot, however, be mounted with the arrow pointing below horizontal or upside down. (top)
Can a rotating electrical connector be mounted by the upper bushing?
Yes in special circumstances. In the case of a vertical mounting (or a mounting somewhat vertical) where the rotating electrical connector needs to be mounted below the rotating device, the rotating electrical connector will need to be attached by the upper bushing into the mounting shaft or collar. In this case the body and lower bushing will be stationary and free floating. It is very important that the mounting be straight and centered so there is zero or minimal lateral motion or wobbling of the body, less than .005 inch TIR is recommended. (top)
What types of wire connections are needed?
All the larger rotating electrical connectors with tab connections are supplied with push on disconnects. The smaller Coaxial rotating electrical connectors use plugs available separately for each model to which customer wires may be soldered. When connecting wires to the stationary floating end of the rotating electrical connector allow sufficient length as not to pull on the connector. Do not attempt to solder wires directly to rotating electrical connector terminals. This will damage interior parts causing the connector to fail, and void the warranty. (top)
Can I solder wires to the rotating electrical connector?
No. Attempting to solder wires directly to a rotating electrical connector will overheat and damage the internal parts, cause connector failure, and void the warranty. Appropriate disconnects are available for rotating electrical connectors and always should be used. (top)
Can standard industrial coax plugs be used on rotating electrical Coaxial connectors?
No. Because the design of the Coaxial rotating electrical connector is unique, standard industry plugs cannot be used. Accessory plugs are available from Progressive Engineering. (top)
What if I need more than eight conductors?
The eight conductor rotating electrical connector is currently the largest connector available. There are two options if more than eight conductors are needed. First if there is access to both ends of the rotating axis, two rotating electrical connectors could be used. This would increase the amount of conductors available to a maximum of sixteen. If this is not a possibility, a rotating electrical connector could be combined with a standard slip ring that has a hole in the center. The rotating electrical connector would be used for the sensitive signal connections and the slipring for any power connections. (top)
Can rotating electrical connectors be used in damp or corrosive environments?
It depends on how damp or corrosive the environment is. While rotating electrical connectors are constructed of corrosion resistant materials they might not be suitable for all applications depending upon which corrosives they are exposed to. They also are not suitable to be used in “wet” environments without protection. Rotating electrical connectors are available with a stainless steel ball bearing for use in damp or corrosive environments. We also recommend the use of the accessory “Boot Kit” for additional protection with the Modular series models. This increases the IP protection rating of the rotating electrical connector to IP53. (top)
Can rotating electrical connectors be used in a vacuum?
No. Because rotating electrical connectors contain liquid substances, a vacuum would tend to cause out gassing and also create internal pressure. This would cause increased rotational torque and possible failure of the connector. (top)
How long can I expect a rotating electrical connector to last?
All rotating electrical connector are warranted for one full year from delivery. The life expectancy depends on several application specific factors such as vibration, temperature, RPM, mounting eccentricity, etc. and therefore cannot be accurately predicted for all applications. However, with no vibration and all other specs being within tolerances, rotating electrical connector typically give years of trouble free service. Under controlled test conditions they typically last for more than a billion revolutions without maintenance. (top)
How does movement or vibration in my machine affect the rotating electrical connector?
Vibration can significantly shorten the life of the rotating electrical connector or even cause failure. Vibration moves the liquid metal conductor away from the contact area, which can cause open or shorted channels. If vibration is present in the application a vibration isolating mounting should be used to mount the rotating electrical connector. (top)
What is the usual delivery time once an order is placed?
All standard models of rotating electrical connectors are maintained in stock in reasonable quantities. Normal delivery is by courier, so delivery time is usually one to five business days depending on distance from Mumbai.(top)
Do you offer any models with a hole in the center?
At this time, we do not offer any models with a pass through hole in the center. Rotating electrical connectors are designed to be compact for mounting at the end of the rotating axis, which makes them less expensive and more durable. (top)
What part rotates?
In fact, either end can be attached to the rotating device. However, as described in answer
No. 5, it is preferable to mount rotating electrical connector so that the body rotates. The body and lower bushing are pressed together as one unit. The upper bushing
(as identified by the "UP" arrow on the body) is mounted to a ball bearing and turns independently of the body. Please see the rotating model below which shows the body and lower bushing rotating with the upper bushing stationary. If a unit needs to be mounted vertically, below the rotating device, then mounting the rotating electrical connecot by the upper bushing with the body floating stationary is acceptable. (top)
For additional information - click on the following:
How Does a Slip Ring Work?
What is a Commutator?
What manufacturing applications have replaced the traditional slip ring assembly with rotating electrical connectors?

Progressive Engineering
Work : 20, Harichand Mill Compound.
Next to Subodh Textiles.
Off LBS Marg. Vikhroli (w), Mumbai 400079, INDIA
Tel : + 91 22 30944289, 25796760,
Tel Fax : + 91 22 257 94 835
Email : progressive_eng@vsnl.net