BS EN 2234-2018 pdf free download.Aerospace series – Cable, electrical, fire resistant – Technical specification
This document specifies the required characteristics and test procedures for fire resistant or fire-proof electrical cables for use in aircraft electrical systems. These cables should also maintain a specific surface resistance when they are subjected to a flame of 1 100 °C after 5 minutes (fire resistant) or 15 minutes (fire-proof) exposure.
The insulation of these cables is designed to withstand aircraft voltages at a frequency not exceeding 2 000 Hz. Unless specified by individual product standards the maximum demonstrated ac voltage of rating of these cables is 115 V rms (phase to neutral) and 200 V rms (phase to phase) and a long term temperature of up to 260 °C (ambient temperature plus temperature rise in conductor).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 3475‑100, (all parts), Aerospace series — Cables, electrical, aircraft use — Test methods — Part 100: General
EN 3838, Aerospace series — Requirements and tests on user-applied markings on aircraft electrical cables
EN 9102, Aerospace series — Quality systems — First article inspection
EN 9133, Aerospace series — Quality Management Systems — Qualification Procedure for Aerospace Standard Products
ISO 2574, Aircraft — Electrical cables — Identification marking
ISO 8815, Aircraft — Electrical cables and cable harnesses — Vocabulary
IEC 60028:1925, International standard of resistance for copper
3 Terms, definitions and symbols
For the purposes of this document, the terms, definitions and symbols given in ISO 8815 and EN 3475‑100 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Materials and construction
4.1 Conductors
4.1.1 Materials
The individual strands used for the conductors shall be cylindrical and shall be:
— of nickel clad copper alloy for nominal cross section of 0,25 mm 2 and 0,4 mm 2 ;
— of nickel clad copper for nominal sections ≥ 0,6 mm 2 .
The copper shall meet the requirements of IEC 60028 and the copper alloy the requirements of this standard.
The nickel shall not represent less than 27 % of the total mass of the individual strand.
Individual strands shall show the following minimum breaking strength:
— 280 N/mm 2 for nickel clad copper;
— 315 N/mm 2 for nickel clad copper alloy.
4.1.2 Lay length
Up to 9 mm 2 cross section inclusive (code 090), concentric or unilay conductors are used. The lay for the stranded conductor, checked over the outside layer of a test piece 1 m long, shall be between 8 times and 16 times the maximum diameter of this conductor.
For sectional areas between 14 mm 2 and 68 mm 2 (codes 140 to 680), the conductor comprises
concentric or bunched conductors twisted together. The lay of the strands for the basic concentric or bunched conductors shall not exceed 30 times the diameter of the concentric or bunched conductor in question.
The lay for concentric (or bunched) conductors, measured over the outer layer of the conductor, shall be between 8 times and 16 times the maximum conductor diameter.
In all cases the lay of the outer layer shall be left-hand.
4.1.3 Joints
The conductors shall be free from any joints. Each strand comprising the conductors may, however,include soldered or brazed joints. For strands with a diameter of 0,25 mm or greater, butt joints shall be used.
The distance between two joints in individual strands shall exceed 3 m, measured between different strands.
4.1.4 Compaction
Compaction of the causing deformation of the strands or damage to the plating is not permitted.
4.2 Construction
Finished cables
The insulation shall be of a material, which takes on the circular shape of the conductor throughout its length. It shall closely cover the conductor without adhering to it, so that it reduces the corona effect and the risk of blistering and heat corrosion due to voids and gaseous discharges.
The insulation shall be neither too tight nor too loose, so as to provide satisfactory mechanical characteristics and be easily removable using commercially available tools. (See Table 1, § 6.45).
The protective sheath shall be of a material, which takes on the round shape of the insulated conductor lying under it. It shall provide adequate protection from mechanical damage and contamination by liquids, as specified in the product standard. The outer surface shall be smooth and suitable for identification marking.
The protective sheath shall not have a corrosive effect on the screen and shall be resistant to fungus and other.
5 Required characteristics
The characteristics of the cables, tested according to the methods described hereafter shall comply with the values given in the product standard.BS EN 2234 pdf download.