X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mx2.grc.nasa.gov ([128.156.11.69] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 951040 for flyrotary@lancaironline.net; Fri, 20 May 2005 11:42:25 -0400 Received-SPF: pass receiver=logan.com; client-ip=128.156.11.69; envelope-from=Joseph.M.Berki@grc.nasa.gov Received: from lombok-fi.grc.nasa.gov (seraph1.grc.nasa.gov [128.156.10.10]) by mx2.grc.nasa.gov (Postfix) with ESMTP id 8B320C329 for ; Fri, 20 May 2005 11:41:39 -0400 (EDT) Received: from apataki.grc.nasa.gov (apataki.grc.nasa.gov [139.88.112.35]) by lombok-fi.grc.nasa.gov (NASA GRC TCPD 8.12.10/8.12.10) with ESMTP id j4KFfcK9026495 for ; Fri, 20 May 2005 11:41:38 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by apataki.grc.nasa.gov (NASA GRC TCPD 8.13.1/8.13.1) with ESMTP id j4KFfchW017814 for ; Fri, 20 May 2005 11:41:38 -0400 (EDT) Received: from apataki.grc.nasa.gov ([127.0.0.1])by localhost (apataki.grc.n asa.gov [127.0.0.1]) (amavisd-new, port 10024)with ESMTP id 14086-20 for ;Fri, 20 May 2005 11:41:38 -0400 (EDT) Received: from GR7700013583.lerc.nasa.gov (gr7700013583.grc.nasa.gov [139.88 .139.62])by apataki.grc.nasa.gov (NASA GRC TCPD 8.13.1/8.13.1) with ESMTP i d j4KFfXQc017752for ; Fri, 20 May 2005 11:41:3 3 -0400 (EDT) X-Info: ODIN / NASA Glenn Research Center Message-Id: <5.1.1.5.2.20050520113742.01dd9f28@popserve.lerc.nasa.gov> X-Sender: scberki@popserve.lerc.nasa.gov X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Date: Fri, 20 May 2005 11:41:28 -0400 To: "Rotary motors in aircraft" From: Joseph M Berki Subject: Re: [FlyRotary] Re: More MAP measurement questions In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_-1232761375==.ALT" X-imss-version: 2.19 X-imss-result: Passed X-imss-approveListMatch: *@*.NASA.GOV --=====================_-1232761375==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed The reason why most people break the shield is to prevent a ground loop. Current flows in the shield if two systems connected together are at different ground potentials. Why are they at different potentials? Are you using a single point grounding scheme? Joe Berki At 11:16 AM 5/20/2005 -0400, you (John Slade) wrote: >Both ends need to be grounded and do not use the shield as a conductor for >any function. Data running in adjacent cables can be corrupted by >currents in cables next to them. If the shields are not grounded at both >ends you have created an antenna. > >Hi Joe, >That's contrary to what I've read in various places (ie aeroelectric >connection). Its my understanding that only one end should be grounded, >otherwise you have a potential difference, and current, along the shield. > >Which is right? - anyone? --=====================_-1232761375==.ALT Content-Type: text/html; charset="us-ascii" The reason why most people break the shield is to prevent a ground loop. Current flows in the shield if two systems connected together are at different ground potentials. Why are they at different potentials? Are you using a single point grounding scheme?

Joe Berki

At 11:16 AM 5/20/2005 -0400, you (John Slade) wrote:

Both ends need to be grounded and do not use the shield as a conductor for any function. Data running in adjacent cables can be corrupted by currents in cables next to them. If the shields are not grounded at both ends you have created an antenna.

Hi Joe,
That's contrary to what I've read in various places (ie aeroelectric connection). Its my understanding that only one end should be grounded, otherwise you have a potential difference, and current, along the shield.

Which is right? - anyone?

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