Hi all, please help a newbie to understand the intentions of DO-160 lightning tests.
Do I understand this correctly: All section 22 lightning tests are between the pin and the case of the equipment unless there is a "Local Ground"? And "Local Ground" applies *only* if the connection is shorter than 1m *and* to the same structure as the equipment is mounted to? So a 2m power supply wire pair (0V, 28VDC) is no "local ground" but a 0,5m wire pair is, resulting in differential mode tests? OTOH, the pin injection test - cable induction setup (Figure 22-14) shows a differential mode test, note 2 says: "transients appear differentially between the aircraft power and return/neutral" and the further wording confuses me "If power and return/neutral originate from a remote Load...". How can power be originating from a "load"? What is a "remote load" in this context? How will be tested if the equipment has one connector with a cable bundle split after 2m: EUT -> connector -> 2m common cable bundle -> Y-split into a) 2m bundle to sensor/motor assembly and b) 2m power leads (28V DC). Is direct pin injection really applied to *all* pins, even pins connected strictly by a prefabricated cable to another assembly? In many cases, normal operation will not be possible as long as signal wires are galvanically connected to a (even idle) generator. Will pass/fail criteria usually be that the EUT shall work after unpowering and undoing all modifications needed to conduct the tests, but the EUT doesn't need to work during the tests? Otherwise it would be hard to impossible although 22.5.1 c. writes "When testing a unit with power applied, a suitable means must be used to ensure that the transient generator does not produce excessive loading of power supply or signal lines" but I can't think of any "suitable means" feeding the (wideband, low impedance) lightning pulse while not disturbing a sensor or communications signal. Applying letter e. cable induction testing "to ease possible testing difficulties" leaves open how the pulse shall be coupled to the line. There is only a description of a "cable induction pin test setup" for power pins (figure 22-14) but not for signal pins. This may be a matter of getting used to it, but I find the DO-160 more ambiguous than industrial EMC standards. TIA Oliver - ---------------------------------------------------------------- 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
