The conductive slip rings we manufacture or use must ensure that they can reliably conduct power and lights without being affected by electrical noise. This article looks at what causes slip ring electrical noise and how to test it.

It is well known that conductive slip rings can be used in electrical motors, generators or torsional transmission assemblies to transmit power and data between torsional and stationary components. Under ideal conditions, the electric slip ring will provide a perfect transmission line without any distortion to the conducting medium (power, signal). In practice, however, there will always be a certain degree of interference or error that distorts the transmission. This may be commonly referred to as electrical noise.

If you are a user or manufacturer of slip rings, it will definitely help to understand the effects of electrical noise and how to test for electrical noise. Excessive electrical noise can result in uninterrupted power delivery, degrade light quality, and certain types of noise can also signal impending slip ring failure.

This article makes us appreciate the importance of electrical noise. Then, we take a closer look at how slip rings work and how electrical noise occurs.

The signal quality of sliding electrical contacts was a very important consideration in the 1950s, when inertial guidance platforms or inertial measurement units (IMUs) were being miniaturized and developed, mostly for rockets and aircraft. These inertial measurement units (imu) usually contain three orthogonal velocity gyroscopes and three orthogonal accelerometers, which measure angular velocity and linear acceleration, respectively.

Each of these three axes requires a set of sliding contacts (conductive slip rings) to transmit the sensor's light signal to the motor that drives the gyroscope and electronics. These slip rings must be very small and reliable, but most importantly, they must transmit light signals without adding significant electrical noise (ie, fidelity transmission).

The researchers solved this problem by electroplating gold on the conductive ring, using a precious metal brush on the stationary bracket to provide sliding contact.

Early slip rings needed to deal with the low intensity of the analog signal, the measurement bandwidth was usually less than 10 kHz, and the signal amplitude was even as low as a few millivolts. Therefore, if the signal noise is also at the millivolt level, it will seriously reduce the quality of the signal. Of course, the requirements for transferring data from analog to digital have changed, but lamp noise is still an important indicator when evaluating the functioning of a conductive sliding electrical contact.