I have used slip rings in similar applications before, one high speed and one low speed. Mercury wetted slip rings have excellent low noise characteristics. Expensive though.
For a high speed low current application we used a straight spring wire which made side contact with the slip ring and was also free from contact noise. John McAuley Sent from my iPhone On 3 May 2012, at 19:37, Macy <m...@basicisp.net> wrote: > EMI considerations: emanations relate to amount of energy available, little > energy = little emanations > 1. voltage surges are usually 'shielded' by metal structures, including the > slip ring. > 2. current surges are related to the amount of current being carried and area > of the loop. Small amount of current in combination with small loop area = > little emanations. > 3. spectral content - pretty low frequency, in my experience the rise and > fall times of mechanical contacts making and breaking are extremely slow, in > the audio range. which translates to... > * Radiated Emissions above 30MHz is unlikely > * Conducted Emissions in the 10kHz to 30MHz range is possible being caused by > capacitive coupling of voltage or inductive coupling of CURRENT [the most > likely transfer path]. Easy to mitigate with twisted pairs and reduced loops > [both source loop *and* receive loop], lowered power, and proximity [move > away from each other]. > > Forgot to add, assume this is in atmosphere, changes if in vacuum. > > Regards, > Robert > > > --- david.car...@plexus.com wrote: > > From: "David Carney (Neenah)" <david.car...@plexus.com> > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: [PSES] Slip Rings and EMI > Date: Thu, 3 May 2012 12:18:48 -0500 > > We're considering a slip ring in a design to pass some wires through a > rotating motor shaft, and we have never used one before. Are there any > EMI concerns with this architecture? If there are concerns, what types > of mitigations are used for EMI when slip rings are used? If slip rings > are to be avoided for certain types of signals due to EMI concerns, what > other alternatives should we consider? > > Thanks. > > David T. Carney P.E. (WI) > Senior Design Engineer > Plexus Engineering Solutions > Neenah Design Center > 920.751.5646 > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <emc-p...@ieee.org> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <emcp...@radiusnorth.net> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org> > David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
