I am designing a system where I have a set of 4 electrical components rotating in a circle. In the bottom stage, the electrical component is submerged in water. In the top stage, the electrical component needs to attach to a high voltage rail. I have a few ideas for this connection, but I don't like most of them. Was looking for some input from here on ideas for this connection point (rotate in and contact, rotate out and release contact). Cost isn't a big issue here.

System Diagram

  • 1
    $\begingroup$ my first thought is to have leaf springs (bits of metal)sticking out on the ends of the components to make contact with the rail $\endgroup$
    – user253751
    Feb 22, 2022 at 18:38
  • $\begingroup$ you must specify , lead impedance, R+jX, arc voltage , suppression method, and a few other things $\endgroup$ Aug 22, 2022 at 4:03

2 Answers 2


The safest would be to inductively couple the power and the device; similar to how a toothbrush charger works. Alternating current electricity goes through one side of the transformer, the magnetic field transfers the energy to the electronic load via a second transformer and power supply electronics. This will be a bit more expensive because each set of electronics will need this inductively coupled power supply. Depending on your configuration you may be able to mount the inductive coupler at the axis of rotation and one unit could power all of the devices at all times. Inductive coupling will be the safest option because there will be no exposed electrical connections.

The lowest cost (for a given power density) and riskiest option would be to use brushes. You would want to make sure you use proper safety measures to make sure humans were prevented from entering the area while the device is powered.


It is not clear, which part of setup you are asking about.

Old TVs and some radios have heterodyne module of such design, where contour coils or even small PCBs with active components switched with knob. Example: https://www.rfcafe.com/references/popular-electronics/taming-tv-tuner-popular-electronics-march-1967.htm They require cleaning, may be, every decade or two.

To drive such drum, obvious choice is to use AC or DC geared motor. Usage of maltese-cross gear is advisable to get good contact and overall simple and reliable operation.

Transformer with separate detachable switchable coils, or rotary transformer as signal and power coupler will require design and manufacturing of it and of additional electronic circuits both for rotor and stator parts, as it transfers only AC signal.

There will be a problem, what will happen when wet device will be powered on. If it is hermetic, then drying or blowing of at least connector part will be required.

Simplest and most reliable solution, i think, is to keep all devices always connected and assembled in parallel, dip them into water, then pull out and test. In this setup you can use just 4 (or much more) sets of typical relays to do sequential test, just like in typical test equipment, and simple up-down mechanism.


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