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Forum Index : Electronics : slip rings
| Author | Message | ||||
| HeadsUp Regular Member  Joined: 06/12/2009 Location: AustraliaPosts: 43 |
anyone able to point me at slip ring assemblies off the shelf ? hoping to get one with 4 poles so i can put 3 phases through it plus a lightning rod earth........... yeah..... means its got to be a heavy duty mutha |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Forget about using slip rings for lightning conduction. Use the tower. Try and keep electricals well insulated from the tower, and use a good earth stake at base of tower, well bonded to the tower, so shortest path is down the tower. Very hard to protect against a direct hit. Insulation and physical separation of electrical paths offers most protection. MOV on inputs to sensitive components can offer protection from leakage from main strike. Gordon. become more energy aware |
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| HeadsUp Regular Member Joined: 06/12/2009 Location: AustraliaPosts: 43 |
thanks but lightning destroys slew bearings in small turbines the bearings would only be worth $20 - 30 so its not a big deal and wouldnt matter , but on bigger units from 10 kW and above a slew bearing could be a couple of thousand to replace , plus , if you rely on the slew bearing to carry lightning to the ground it may not provide a perfect conduction and the lightning may try to find a path through other things causing more damage. i know the large 100 kW plus turbines have lightning conductors in each blade , but i wont be going to that extent while i have insulated material like GRP for blade construction , thinking more of a lightning rod at the top of the nacelle , with 35 mm sq cable to carry it down to an earth stake. where people use indirect drive , a rubber flexible coupling can double as an insulator to protect the generator , but direct drive would require a bit of deeper thought to protect inverters. i have used many lightning protectors on AC mains , phone lines , TV antennas and CCTV systems , but never played with 3 phase stuff so i am all ears if anyone has suggestions found these with an online search but they are only 3 phase , we really want protection on the DC input before it gets to the rectifier http://www.cattech.com.au/lightningman/item.jsp?item=DSD340T NC275&backPage=product.jsp&STMP=100118095537983 |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
On my windmill, the tower extends upwards through the Yaw bearings. I have slip rings. The Nacelle is free to rotate around the Yaw bearings, but solid steel extends up through the centre. A lightning rod could be attached to the solid steel, and extended to above the blade height. This might not be possible on a sleeved pipe bearing system with the wires feeding down the centre without slip rings. On another track, I lived in lightning central "Darwin" and had many coax to UHF antennae blown out, with the transmitter surviving. The single loop in the coax, just under the antennae, provided a big enough resistance for the energy to preferably burn through the loop and continue down the tower. This could work with a windmill as well. Gordon. become more energy aware |
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| HeadsUp Regular Member Joined: 06/12/2009 Location: AustraliaPosts: 43 |
Yes that could work effectively ,small diameter tube passing right up through the center of the nacelle ,lightning rod attached to top of tube and a hollow slip ring assembly could still be slid down over the tower upper tube , provided the cables are well insulated where they pass through to the center of the pipe , the slip ring brush carrier is then fixed to the nacelle chassis brilliant . didnt know about putting a loop in coax but it sounds like that works perfectly well i have used coax / BNC surge protectors inline before on CCTV cameras ( cost around $ 45 each ) i just got an email reply from http://www.lightningman.com.au/index1.html , very smart boy he has advised me of 50 zillion aspects to protection systems i wasnt aware of with a two page email i will post the gist of it here after work . |
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imsmooth Senior Member Joined: 07/02/2008 Location: United StatesPosts: 214 |
I used a mercury slip ring. You can see its implementation here. I have had no trouble with it. It works great. |
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