BS 3475-604:2010 pdf download – Cables, electrical, aircraft use — Test methods — Part 604: Resistance to dry arc propagation

BS 3475-604:2010 pdf download – Cables, electrical, aircraft use — Test methods — Part 604: Resistance to dry arc propagation 5.2 Test equipment Construct an apparatus as shown diagrammatically in figures 3a, 3b and 3c which includes the following minimum provisions: a) A lightweight, freely pivoting test fixture to hold the blade at a 90° angle to the specimen and to exert a controlled force on the specimen. NOTE Generally a mounting on 50 mm centres shall hold the individual cables of the specimen in close proximity. b) Electrical terminations to provide a ready means of connecting test specimens into the circuit as shown in figure 2. c) An aluminium blade complying with material specification T6061 -T6 (EN 2702) and figure 3c. d) A mechanism to provide a minimum oscillating stroke of 1 5 mm excursion at a frequency of (8 ± 2 ) Hz. e) A blade carrier to give a downward force at the blade of (2,5 ± 0,1 ) N. f) A mechanical stop to limit the fall of the oscillating blade to within an accuracy of 0,2 mm measured at the point of contact. g) Means of separating the blade from the specimen, both manually and automatically if used. h) An electrical connection of the aluminium blade to the neutral of the test power supply (see 5.1 h). i) A transparent enclosure to protect personnel from ejected molten metal and short wavelength ultra violet light. 5.3 Test protocol 5.3.1 The procedure embraces cables sizes 26 to 1 0, and for each cable size six values of prospective fault current have been defined. Performance of a cable size at a given fault intensity shall be determined by testing three samples. Thus 1 8 samples are required for every cable size. 5.3.2 For the purposes of cable qualification at least sizes 24, 20 and 1 4 shall be tested. Additional testing of other sizes may be deemed necessary in particular cases and values of prospective fault currents, the ratings of thermal breaker protection which are typical of aircraft use and the blade form to be employed have been included in this specification. 5.3.3 It is emphasised that electrical arcing tests are essentially destructive and can be hazardous to personnel. Therefore tests shall be undertaken with all observers shielded from direct physical and visual exposure as noted in 5.2 i). The use of video recording for all tests is...