The issue is with primary power: that supplied by the platform to electrical and electronic loads. It does not apply to secondary power developed in a load and supplied to another load. It has nothing to do with dc vs. ac. If a load were supplied with 28 Vdc power from an aircraft platform and subsequently converted that to say 24 Vac at 400 cycles to run some other circuitry, the dc power would be subjected to the wording you cited, but the ac power would not.
Ken Javor Phone: (256) 650-5261 From: "James Pawson (U3C)" <ja...@unit3compliance.co.uk> Reply-To: "James Pawson (U3C)" <ja...@unit3compliance.co.uk> Date: Tue, 15 Jan 2019 08:21:24 -0000 To: <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [PSES] MIL-STD-461 and power cables sanity check Hello all, MIL-STD-461 has a requirement for any conductors in a cable assembly carrying ³primary power² i.e. AC power from a vessel distribution bus to be separated out from the main cable bunch and routed separately in a test setup (clause 4.3.8.6). It also states that the primary power cables shall not be shielded. I understand the rationale for this, the explanatory notes at the end of the standard are most helpful. My interpretation is that: 1. this only applies to AC power buses (like those referenced in MIL-STD-1399 <http://everyspec.com/MIL-STD/MIL-STD-1300-1399/MIL-STD-1399-300B_13192/> ) and not to DC power supplied from another part of the EUT or from some Associated Equipment 2. power supplied in this fashion can be supplied within a shielded cable if that is what is specified in the final installation Having not done any MIL-STD work before I just wanted to make sure my interpretation was correct? Many thanks as always, James James Pawson Unit 3 Compliance - ---------------------------------------------------------------- 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://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> 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://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
