Electrical Short Circuit/Arcing of Aged Aircraft Wiring

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$Atago Co., Ltd. Salinity Refractometer, Model S-10 Instruction Manual$

Figure 38. Test 16 A: Sample during the metal shaving abrader test 90° (right angle).Figure 39. Test 16 A: Damage sample after metal shaving abrader 90° (right angle) test.Note that the broken wire was due to flexing and not the action of the shaving.Electrical Arcing of Aged Aircraft Wire.Lectromechanical Design CompanyReport No. N191-RPT4AU99 August 12, 199946
Test 17 & 192 Bundles: four wires each (three BMS 42/1/1-20; one 3 BMS 42A/8/1-18)Metal Shaving: Two steel shavings placed ~1 apart between bundlesCircuit Resistance: 1 OhmGenerator: 3 phase, 400Hz, 120 line to neutral (208 line to line), 10 kVA.Observations Test 17 Test 19Flash Yes NoStrong Arcing No NoCircuit Breakers Tripped No NoDamage Length 0 0# Wires Failing Wet Dielectric Test 2 of 8 2 of 8In both of these tests the steels shavings did damage to the insulation that exposed theconductor. In the case of Test 17 the shaving was arranged so that the movement of a shavingbetween the bundles caused a steady abrasion of the insulation (Figure 40) over the course of anhour. However, before the damage reached to the conductor the shaving was disrupted slightly(by an ohmmeter probe) which caused the shaving to move via the motion of the bundles to anew location. Here, the shaving chaffed through the insulation and caused a flash in a matter ofminutes (Figure 41). The flash did not turn in to strong arcing and the shaving then moved to anew location where it continued to chaff the insulation. The test was ended before the samplecould flash again.The oscillogram shows 6 current peaks of up to 75 amperes that occurred during the flashevent. Examination of the sample showed severe abrasion damage and a little soot near therepoint where the wire flashed (Figure 42).In Test 19 the shaving used was thinner (49 mils by 18 mils) and the abrasion patternswere more like short cuts in the insulation (Figure 43). There were no flashing events during the4 hour duration of the test. However, two of the eight wires failed the wet dielectric test. Thepoints of failure on these wires were at cuts that were deeper than they first appeared. From thelocation of the cuts it appears that different shavings made the cuts and therefore they could notcause a flash event.Electrical Arcing of Aged Aircraft Wire.Lectromechanical Design CompanyReport No. N191-RPT4AU99 August 12, 199947
Page 3 and 4: Electrical Arcing of Aged Aircraft
Page 5 and 6: were placed between wires in small
Page 7 and 8: BackgroundArc tracking of aircraft
Page 9 and 10: EXPERIMENTAL PROCEDURESWet Arc Trac
Page 11 and 12: Figure 5. Circuit used in the metal
Page 13 and 14: Figure 8. Apparatus used for metal
Page 15 and 16: DESCRIPTION OF ELECTRICAL ACTIVITYT
Page 17 and 18: The voltage and current waveforms w
Page 19 and 20: Figure 15. Example of a strong arci
Page 21 and 22: RESULTSTable 1 lists the Test run g
Page 23 and 24: Table 3. Summary of Metal Shavings
Page 25 and 26: APPENDIX A: Description of Individu
Page 27 and 28: Test 1 & 2Wet Arc TrackingBundle: S
Page 29 and 30: Figure 22. Test 1: Oscillogram show
Page 31 and 32: Test 3Wet Arc TrackingBundle: Seven
Page 33 and 34: Figure 26. Test 3: Sample bundle af
Page 35 and 36: Figure 27. Test 4: Strong arcing on
Page 37 and 38: Test 6 & 7Wet Arc TrackingBundle: S
Page 39 and 40: Figure 32. Test 6: Sample bundle af
Page 41 and 42: Test 9:Bundle: Seven wires (6 over
Page 49 and 50: Figure 37. Test 14: Electrical powe
Page 51: Metal Shavings AbrasionTest 16 A &
Page 55 and 56: Figure 42. Test 17: Damage to wire
Page 57 and 58: Figure 44. Test 20: Damage done in
Page 59 and 60: Table 7. Description of alternate a

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