View Latest Blog Entries
Close
Categories
Testing & Assessment Certification Standard & Regulation Aging Wires & Systems Maintenance & Sustainment Management Conference & Report Protection & Prevention Research Miscellaneous Arcing
Popular Tags
Visual Inspection High Voltage AS50881 MIL-HDBK MIL-HDBK-525 FAR AS4373 Electromagnetic Interference (EMI) Maintenance FAR 25.1707 Wire System Arcing Damage
All Tags in Alphabetical Order
2021 25.1701 25.1703 abrasion AC 33.4-3 AC 43 Accelerated Aging ADMT Aging Systems AIR6808 AIR7502 Aircraft Power System aircraft safety Aircraft Service Life Extension Program (SLEP) altitude arc damage Arc Damage Modeling Tool Arc Fault (AF) Arc Fault Circuit Breaker (AFCB) Arc Track Resistance Arcing Arcing Damage AS22759 AS22759/87 AS23053 AS29606 AS4373 AS4373 Method 704 AS50881 AS5692 AS6019 AS6324 AS81824 AS83519 AS85049 AS85485 AS85485 Wire Standard ASTM B355 ASTM B470 ASTM D150 ASTM D2671 ASTM D8355 ASTM D876 ASTM F2639 ASTM F2696 ASTM F2799 ASTM F3230 ASTM F3309 ATSRAC Attenuation Automated Wire Testing System (AWTS) Automotive Avionics backshell batteries bend radius Bent Pin Analysis Best of Lectromec Best Practice bonding Cable Cable Bend cable testing Carbon Nanotube (CNT) Certification cfr 25.1717 Chafing Chemical Testing Circuit Breaker circuit design Circuit Protection cleaning clearance Coaxial cable cold bend collision comparative analysis Compliance Component Selection Condition Based Maintenance Conductor Conductor Testing conductors conduit Connector Connector rating connector selection connector testing connectors contacts Corona Corrosion Corrosion Preventing Compound (CPC) corrosion prevention Cracking creepage D-sub data analysis data cables degradat Degradation Delamination Derating design safety development diagnostic Dielectric breakdown dielectric constant Dimensional Life disinfectant Distributed Power System DO-160 dry arc dynamic cut through E-CFR electric aircraft Electrical Aircraft Electrical Component Electrical Power Electrical Testing Electrified Vehicles Electromagnetic Interference (EMI) Electromagnetic Vulnerability (EMV) Electrostatic Discharge EMC EMF EN2235 EN3197 EN3475 EN6059 End of Service Life End of Year Energy Storage engines Environmental Environmental Cycling environmental stress ethernet eVTOL EWIS certification EWIS Component EWIS Design EWIS Failure EWIS sustainment EWIS Thermal Management EZAP FAA FAA AC 25.27 FAA AC 25.981-1C FAA Meeting failure conditions Failure Database Failure Modes and Effects Analysis (FMEA) FAQs FAR FAR 25.1703 FAR 25.1707 FAR 25.1709 Fault fault tree Fixturing Flammability fleet reliability Flex Testing fluid exposure Fluid Immersion Forced Hydrolysis fuel system fuel tank ignition Functional Hazard Assessment functional testing Fundamental Articles Fuse Future Tech galvanic corrosion Glycol Gold Gold plating Green Taxiing Grounding hand sanitizer handbook Harness Design harness protection hazard Hazard Analysis health monitoring heat shrink heat shrink tubing high current high Frequency high speed data cable High Voltage High Voltage Degradation HIRF History Hot Stamping Humidity Variation HV connector HV system ICAs IEC 60851 IEC60172 IEEE immersion insertion loss Inspection installation installation safety Instructions for Continued Airworthiness insulating material insulating tape Insulation insulation breakdown insulation resistance insulation testing interchangeability IPC-D-620 ISO 17025 Certified Lab ISO 9000 J1673 Kapton Laser Marking life limit life limited parts Life prediction life projection Lightning lightning protection liquid nitrogen lithium battery lunar Magnet wire maintainability Maintenance Maintenance costs Mandrel mean free path measurement mechanical stress Mechanical Testing MECSIP MIL-C-38999 MIL-C-85485 MIL-DTL-17 MIL-DTL-23053E MIL-DTL-3885G MIL-DTL-38999 MIL-E-25499 MIL-HDBK MIL-HDBK-1646 MIL-HDBK-217 MIL-HDBK-454 MIL-HDBK-516 MIL-HDBK-522 MIL-HDBK-525 MIL-HDBK-683 MIL-STD-1353 MIL-STD-1560 MIL-STD-1798 MIL-STD-464 MIL-T-7928 MIL-T-7928/5 MIL-T-81490 MIL-W-22759/87 MIL-W-5088 MIL–STD–5088 Military 5088 modeling moon MS3320 NASA NEMA27500 Nickel nickel plating No Fault Found OEM off gassing Outgassing Over current Overheating of Wire Harness Parallel Arcing part selection Partial Discharge partial discharge at altitude Performance physical hazard assessment Physical Testing polyamide polyimdie Polyimide-PTFE Power over Ethernet power system Power systems predictive maintenance Presentation Preventative Maintenance Program Probability of Failure Product Quality PTFE pull through Radiation Red Plague Corrosion Reduction of Hazardous Substances (RoHS) regulations relays Reliability Research Resistance Revision C Rewiring Project Risk Assessment S&T Meeting SAE SAE Committee Sanitizing Fluids Secondary Harness Protection separation Separation Requirements Series Arcing Service Life Extension Severe Wind and Moisture-Prone (SWAMP) Severity of Failure shelf life Shield Shielding Shrinkage signal signal cable Silver silver plated wire silver-plating skin depth skin effect Small aircraft smoke Solid State Circuit Breaker Space Certified Wires Splice standards Storage stored energy superconductor supportability Sustainment System Voltage Temperature Rating Temperature Variation Test methods Test Pricing Testing testing standard Thermal Circuit Breaker Thermal Endurance Thermal Index Thermal Runaway Thermal Shock Thermal Testing tin Tin plated conductors tin plating tin solder tin whiskering tin whiskers top 5 Transient Troubleshooting TWA800 UAVs UL94 USAF validation verification video Visual Inspection voltage voltage differential Voltage Tolerance volume resistivity vw-1 wet arc white paper whitelisting Winding wire Wire Ampacity Wire Bend Wire Certification Wire Comparison wire damage wire failure wire performance wire properties Wire System wire testing Wire Verification wiring components work unit code

270VDC arcing in aircraft wiring

Research

In a recent presentation to the SAE at the biannual meeting, Lectromec presented a summary of the work that was performed by several companies and the Federal Aviation Administration (FAA) last summer. These tests were performed at the FAA’s Technical Center in Atlantic City on 270VDC in aircraft wiring.

There were four test objectives:

  1. Perform testing that would help groups such as the SAE better understand the damage potential from higher voltage arcing events;
  2. Determine the impact from 270VDC due to direct contact electrical arcing to several target types;
  3. Determine the impact from 270VDC due to indirect arc damage; and
  4. Gather 270VDC arc waveform data for Lectromec’s Arc Damage Modeling Tool (ADMT).

The test configurations and methods used were similar to common arc damage techniques previously reported upon, although some modifications were made to handle the 270VDC power source. In the general test configuration, the power source was run through a contactor and to the arc fault location. The adjustable fault current limiting resistors were placed on the return circuit, as was a fuse to limit the arc duration.

During testing performed during the last decade by the FAA and Lectromec, it was found that the swing test was a good representative test procedure for assessing direct contact arc damage. In these swing tests, a cut is made in the wire insulation such that the conductor is exposed. The ends of the wire are then connected to the circuit and attached to a power source. The target, in this example, a section of aircraft structure, is attached to ground. The test begins by pulling the wire from the target, applying the power, then releasing the wire and allowing it to freely swing into the structure, making contact and creating an arcing event.

An example of the configuration and moment of contact is shown in the following figure.

aerospace wiring
Performance of 270VDC arc damage assessment testing at FAA.
Looking to address your challenges with wire system separation? To find out more read Arc Damage Analysis.

Those present during the tests described the testing as, “…the arc sounded more forceful, more energetic, and the flash also seemed brighter as compared to similar testing performed at 115VAC.”

An example waveform from a swing test is shown below. There are three distinct sections to the waveforms generated from these tests.

Part One: Wire Strike for aerospace wiring

This is where the wire makes first contact with the target and causes the damage. In the scenario below, the arc event lasted for approximately 2ms.

Part Two: Shorting

As the wire continues to move closer to the target surface and a larger portion of the surface area is making contact, it creates a shorting event. The current rises, and the voltage drop across the wire-target interface is reduced such that no further damage is done to the target. The shorting event continues until the next event, fuse opening.

Part Three: Fuse Opening

Here, the fuse trips and ends the event. In the testing shown here, the fuse was selected to open after little more than 50ms. During these tests, custom fuses were used to set the duration of the failure event. The durations ranged from 3ms to approximately 200ms and were selected based on the known response time of 270VDC protections schemes in the field.

aircraft wiring

A couple dozen tests were performed with various circuit protection durations. Close examination of the arcing waveforms from each of these configurations show that the 270VDC waveform is similar to a 28VDC arc, albeit with more energy.

Damage at a distance

The testing was also performed to assess the damage at a distance, the potential damage from the arc plume. Although the test and arc duration were limited (less than 200ms), there was sufficient arc energy to cause a measurable impact up to 0.5” away. Further examination and data gathering is necessary for assessing damage at a distance, but the techniques used, proved to be valid for the test parameters chosen.

Arc Modeling and Assessment

In the review of the data gathered from testing, there was a wealth of information that could be used for Lectromec’s Arc Damage Modeling Tool analysis. The waveforms from the physical tests were used as seed data to determine the modeling parameters.

The simulations results indicate that the arc efficiency (the factor of arc energy used to damage the target) was within anticipated boundaries. Lectromec anticipates examining the ‘damage at a distance’ tests in the next couple of months.

So what does it mean for the designer?

Takeaway #1 – Because there are higher voltages, the designs based on 115VAC need to be reevaluated. The same methods used for assessing arc damage at lower voltages such as 115/208VAC are still valid and can be applied to higher voltage events. The SAE is currently working on the proposed test methods and may enter a round-robin method review in the next year.

Takeaway #2 – Review of the data suggests that the electrical arc has a higher power and may be able to cause damage to physically separated systems. Also, it is important consider that for systems operating on 270VDC, unlike AC arcing, there is no voltage potential crossing reaching zero.

Takeaway #3 – The limited damage shown during these tests was only possible because of the rapid circuit protection response. Selection of circuit protection is critical for system safety and limited failure impact.

The test results and analysis will be included in a paper to be presented later this year.

Michael Traskos

Michael Traskos

President, Lectromec

Michael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components.