Naked Science Forum
Non Life Sciences => Technology => Topic started by: Supervolant on 16/07/2018 11:31:32
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Hello,
I am relatively new to the field of invention, especially the one's using electromechanical devices such as a circuit board or in my case slip rings. If you don't know, slip rings are devices that let electricity flow from an stationary to an rotary part as seen for example in wind turbines. I am in search for a relatively small slip ring which is capable of letting trough high amperage....
So my question is what is IT that makes an electric circuit let flow more or less ampere?
My guess is wieder diameter / gauge cables?
I look forward to your answer since searching the web for half an hour didn't got me further... I thought why not being proactive!
- Robert
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So my question is what is IT that makes an electric circuit let flow more or less ampere?
My guess is wieder diameter / gauge cables?
The conductivity of the metal is another factor ...
https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
Constant-current power-supplies require active-electronics. (https://www.google.com/search?q=constant+current+power+supply+circuit+diagram)
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You don't need sliprings you rotate an electro magnet on the shaft relative to the output windings ,that magnet is powered by windings via semiconductors on the shaft that rotate relative to stationary electromagnets that incorporate the control electronics
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My guess is wieder diameter / gauge cables?
Welcome to the forum Robert.
Your guess is right fo DC but AC produces an effect called skin effect where most of current flows in the outer layer so reducing the effective diameter. At 50-60Hz it doesnt have much effect in cables less than 8mm, but at high frequencies it becomes significant.
Another thing that determines current is the voltage applied across the circuit.
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Sliprings were used on DC motors and generators. But they have some fundamental problems:
- They deliver a current by having two electrical conductors directly rubbing on each other as one part rotates
- "Rubbing" implies friction, which is a waste of energy
- More seriously, "rubbing" means that the conductive surfaces wear out and have to be replaced, which means shutting the machine down for maintenance at frequent intervals
- the best electrical conductors like copper and aluminium are not very wear-resistant, so for the contacts you have to use materials like graphite or mercury (toxic!)
- Often slip-rings have segments, and when the electrical contacts pass from one segment to another, you have arcing/sparking, which erodes the contacts (more maintenance problems!)
See: https://en.wikipedia.org/wiki/Slip_ring
As mentioned in previous posts, modern motors and generators avoid sliprings, and prefer to use non-contact methods like magnetic induction, high-power electronics and powerful permanent magnets instead.
See: https://en.wikipedia.org/wiki/DC_motor#Brushless