BS 2G 215-1-1985 ISO 8056-1-1985.pdf

BRITISH STANDARD AEROSPACE SERIES BS 2G 215-1: 1985 ISO 8056-1: 1985 (Superseding British Standard G 215:1972) Nickel-chromium and nickel-aluminium thermocouple extension cables for aircraft Part 1: Specification for conductors ISO title: Aircraft Nickel-chromium and nickel-aluminium thermocouple extension cables Part 1: Conductors General requirements and tests UDC 629.7:621.315.2 034.245:621.362.1 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 This British Standard, having been prepared under the direction of the Aerospace Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 December 1985 © BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference ACE/6 Draft for comment 84/72756 DC ISBN 0 580 14848 3 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Aerospace Standards Committee (ACE/-) to Technical Committee ACE/6 upon which the following bodies were represented: BEAMA Ltd. British Rubber Manufacturers Association Civil Aviation Authority Electric Cable Makers Confederation Electronic Components Industry Federation Electronic Engineering Association Ministry of Defence National Supervising Inspectorate Society of British Aerospace Companies Limited Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 © BSI 10-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope and field of application1 2References1 3Conductor materials1 4Conductor construction1 5Tests1 Annex Methods for determining thermo-e.m.f. of conductor wires against platinum3 Figure 1 E.M.F. measurement by method of direct comparison against platinum5 Figure 2 E.M.F. measurement by method using a substandard6 Table 1 Details of nickel-chromium and nickel-aluminium conductors2 Table 2 Thermo-electric characteristics of nickel-chromium and nickel-aluminium conductors against platinum2 Table 3 D.C. resistances of nickel-chromium and nickel-aluminium2 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 ii © BSI 10-1999 National foreword This British Standard, has been prepared under the direction of the Aerospace Standards Committee. It is identical with ISO 8056-1:1975 “Aircraft Nickel-chromium and nickel-aluminium thermocouple extension cables Part 1: Conductors General requirements and tests” published by the International Organization for Standardization (ISO). It supersedes British Standard G 215:1972 which is withdrawn, and takes account of international agreement by Technical Committee ISO/TC 20 in relation to the requirements of nickel-chromium and nickel-aluminium thermocouple extension cables for aircraft. This standard is restricted to the requirements for the conductors for the cables whereas British Standard G 215:1972 used to cover the conductor and the insulation requirements for the complete cables. It is intended to cover the complete cable requirements by amendments to the British Standard Aerospace cable standards using this standard as a cross-reference to cover the conductors for thermocouple extension cables. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Where the words “part of ISO 8056” appear, referring to this standard, they should be read as “Part of British Standard 2G 215”. IPTS68 International Practical Temperature Scale of 1968 is obtainable from HMSO. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International StandardCorresponding British Standard IEC Publication 564:1977BS 5764:1979 Specification for d.c. bridges for measuring resistance (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 © BSI 10-19991 1 Scope and field of application This part of ISO 8056 specifies the design requirements and tests for the conductors of thermocouple extension cables, using nickel-chromium and nickel-aluminium, for installation in aircraft temperature indicator and control systems. Methods for determining the thermo-e.m.f. of conductor wires against platinum are given in the Annex . 2 References IEC Publication 564, D.C. bridges for measuring resistance. IPTS 68, International Practical Temperature Scale of 1968. 3 Conductor materials Conductors for use in the construction of thermocouple extension cables for aircraft shall be manufactured from bright, annealed, nickel-chromium (non-magnetic) wires and bright, annealed, nickel-aluminium (magnetic) wires. They shall comply with the requirements specified in Table 1 in terms of d.c. resistance and those in Table 2 in terms of thermo-e.m.f. characteristics against platinum over the appropriate temperature range. Table 3 shows the resistances which have been assumed for nickel-chromium and nickel-aluminium wires in the calculation of d.c. conductor resistances. A maximum increase in length of 4 %, as a result of stranding, has been assumed for the wires of each conductor. Each reel or coil of wire to be used in the manufacture of the conductors shall be tested in accordance with 5.1 and 5.2. Finished conductors shall be tested in accordance with 5.3 and 5.4. Each reel or coil of wire to be used in the manufacture of the conductors shall be tested in accordance with 5.1 and 5.2. Finished conductors shall be tested in accordance with 5.3 and 5.4. 4 Conductor construction The positive conductor shall consist of stranded, bright, annealed, nickel-chromium alloy wires complying with the requirements of clause 3. The negative conductor shall consist of stranded, bright, annealed, nickel-aluminium alloy wires complying with the requirements of clause 3. Joints in single wires shall be welded, brazed or silver-soldered, but the complete conductor shall not be joined. There shall be no kinks, broken wires or other irregularities in the conductors. 5 Tests 5.1 Thermo-electric tests on conductor wires All wires, before stranding, shall be shown to comply with the requirements specified in Table 2 with respect to thermo-e.m.f. against platinum1) over the range of temperature appropriate to the cable under manufacture. Measurements shall be made on sample lengths taken from both ends of each reel or coil of wire. A method of direct comparison against platinum, as described in clause A.1, shall be used where single samples are to be tested. Where large numbers of samples are to be tested, a differential method, as described in clause A.2, using substandards of nickel-chromium and nickel-aluminium as appropriate, may be employed. The substandards used shall have known, traceable thermo-electric characteristics against platinum. In the event of a dispute, the direct comparison method shall take precedence. 5.2 Tests to determine the magnetic significance of conductor wires Each wire, before stranding, shall be checked with a magnet to determine its magnetic significance. Nickel-chromium wires shall be non-magnetic. Nickel-aluminium wires shall be magnetic. 5.3 Thermo-electric tests on conductors of finished cables A sample length shall be cut from one end of each reel or coil of finished cable. The thermo-electric characteristic against platinum of the conductor shall be checked differentially by the method using a substandard, as described in clause A.2, over the temperature range of the cable. This characteristic shall comply with the requirements specified in Table 2. 5.4 Conductor resistance tests Each length of finished cable shall be checked for resistance at 20 ± 1 °C by means of a suitable bridge, as described in IEC Publication 564, of accuracy class no larger than 0,5. Suitable precautions shall be taken to eliminate the effects of parasitic e.m.f.s. The appropriate limits of resistance are given in Table 1. 1) Platinum with a temperature coefficient of resistance not greater than 0,003 925 ± 3 ppm. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 2 © BSI 10-1999 Table 1 Details of nickel-chromium and nickel-aluminium conductors Table 2 Thermo-electric characteristics of nickel-chromium and nickel-aluminium conductors against platinum Table 3 D.C. resistances of nickel-chromium and nickel-aluminium wires Conductor Conductors of Nominal diameter of conductor nickel-chromium Ni-Cr(+)nickel-aluminiumNi-Al() SizeNumber and diameter of wires D.C. resistances at 20 °C max.min.max.min. mm2AWGamm7/1 000 m7/1 000 m7/1 000 m7/1 000 mmm 0,4 0,6 1,0 1,2 2,0 3,0 5,0 22 20 18 16 14 12 10 19/0,15 19/0,2 19/0,25 19/0,3 37/0,25 37/0,32 61/0,32 2 364 1 330 851 591 437 267 162 1 956 1 100 705 489 362 220 133 932 524 336 234 172 106 64 771 434 278 193 143 86 52 0,75 1,00 1,25 1,50 1,75 2,20 2,85 a American Wire Gauge. Temperature Conductors of nickel-chromium (Ni-Cr)nickel-aluminium (Ni-Al) Thermo-e.m.f. against platinum max.min.max.min. °CmVmVmVmV 100 50 0 50 100 150 200 250 300 2,287 1,271 0,060 1,413 2,873 4,418 6,029 7,689 9,382 2,167 1,151 0,060 1,293 2,753 4,298 5,909 7,569 9,262 1,386 0,738 0,060 0,730 1,342 1,839 2,228 2,463 2,945 1,266 0,618 0,060 0,610 1,222 1,719 2,108 2,583 2,825 Wire diameter Conductor of nickel-chromium (Ni-Cr)nickel-aluminium (Ni-Al) D.C. resistances max.min.max.min. mm7/m7/m7/m7/m 0,32 0,30 0,25 0,20 0,15 9,487 10,793 15,54 24,30 43,18 8,162 9,287 13,38 20,90 37,16 3,742 4,258 6,132 9,581 17,03 3,221 3,664 5,276 8,245 14,65 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 © BSI 10-19993 Annex Methods for determining thermo-e.m.f. of conductor wires against platinum A.1 E.M.F. measurement by method of direct comparison against platinum2) (see Figure 1) A.1.1 Sampling A sample length (approximately 1 m) shall be cut from the outer end of each reel or coil of the conductor. In the case of previously untested single wires, a second sample shall be cut from the inner end of each reel. The cut lengths and the reels from which they are taken shall be marked for future reference. A.1.2 Junction formation Each test sample shall be paired with a piece of platinum2) wire of similar length. If there is insulation present, 100 mm shall be removed from both ends of the sample. A sound electrical junction shall be formed between the pair at one end (variable temperature junction). The junction shall include all the wires of each conductor and be as short in length as possible. Its effective diameter shall not exceed the sum of the diameters of the joined conductors by more than 50 %. Similar junctions shall be formed between the free ends of the pair and a pair of copper leads, drawn from an homogeneous source, for connection to a measuring instrument (reference junctions). A.1.3 Reference temperature Each reference junction shall be immersed in an isothermal medium, maintained at a temperature of 0 ± 0,1 °C, the ultimate thermal stability of which is demonstrably unperturbed by the immersion. The depth of immersion shall be not less than 80 mm. A calibrated thermometer, traceable to 0 °C (as defined on IPTS 68) within ± 0,1 °C, shall be used to monitor the reference temperature during the test. A.1.4 Test temperature The variable temperature junction shall be immersed in an isothermal medium, maintained at the required test temperature, the ultimate thermal stability of which is unperturbed by the immersion. The depth of immersion shall be not less than 80 mm. A calibrated thermometer, traceable to appropriate points on IPTS 68 to an uncertainty no greater than ± 0,2 °C, shall be positioned in the medium so that the temperature gradient between its sensing head and the test junction is demonstrably negligible. The heat loss along the thermometer shall be insignificant. The ultimate thermal stability of the medium shall be not less than ± 0,1 °C/min. A.1.5 Precautions The test arrangement shall be such that there is no electrical contact between the conductors except at the junctions and via the measuring instrument. There shall be no electrical contact between any part of the circuit and any external conductor except the measuring instrument. A.1.6 Thermo-e.m.f. test When the thermometer indicates that the system has stabilized at the required temperature, the magnitude and polarity of the e.m.f. appearing between the copper leads shall be measured on a suitable instrument having an uncertainty of not more than ± 0,005 mV. The measurement will normally entail a reversal of connections to the instrument, in which case the magnitude of the e.m.f. is decided by taking the arithmetic mean of the two readings. In determining the polarity of the e.m.f., the platinum limb shall be taken as reference. The result shall be recorded against the reference number of the reel or coil. The estimated uncertainty of measurement for this method of thermo-e.m.f. determination shall be ± 0,02 mV at all test temperatures. A.2 E.M.F. measurement by method using a substandard (see Figure 2) A.2.1 Sampling A sample length (approximately 1 m) shall be cut from the outer end of each reel or coil of the conductor. In the case of previously untested single wires, a second sample shall be cut from the inner end of each reel. The cut lengths and the reels or coils from which they are taken shall be marked for future reference. 2) Platinum with a temperature coefficient of resistance not greater than 0,003 925 ± 3 ppm. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:15:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 215-1:1985 4 © BSI 10-1999 A.2.2 Substandard A substandard conductor, made from the same nominal material as the test sample, shall be established. The thermoe