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1、BRITISH STANDARD BS 2G 114: 1953 Specification for Direct current ratiometer indicators for aircraft UDC 629.13.05:621.317.085 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 This British Standard, having been approved by the
2、Aircraft Industry Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council of the Institution on 19 November 1953 BSI 12-1999 ISBN 0 580 34130 5 Foreword This revised British Standard includes data relating to pl
3、atinum resistance thermometer elements in addition to that given in BS G 114:1949, for nickel resistance thermometer elements. An Appendix has been added, giving information on minimum tests recommended to verify the serviceability of instruments manufactured in compliance with the requirements of t
4、he standard. 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. Summary of pages This docume
5、nt comprises a front cover, an inside front cover, pages i and ii, pages 1 to 5 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. Amendments issued since publication
6、 Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 BSI 12-1999i Contents Page ForewordInside front cover 1Scope1 2Definition1 Section 1. General requirements 3Preferred size of case1 4Preferred units of meas
7、urement1 5General construction1 6Declaration of performance1 Section 2. Particular requirements 7Construction1 Section 3. Tests 8General2 9Position test2 10Ranging test2 11Friction test2 12Voltage test2 13Rotational acceleration test2 14Temperature compensation test2 15Vibration, acceleration and cl
8、imatic proofing tests3 16Insulation resistance3 17Position, ranging and friction tests3 18Insulation resistance test3 Appendix A Temperature-resistance characteristics for nickel resistance thermometer elements4 Appendix B Temperature-resistance characteristics for platinum resistance thermometer el
9、ements4 Appendix C Serviceability tests5 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 BSI 12-19991 1 Scope
10、This British Standard specifies the requirements for direct current ratiometer indicators for applications on aircraft such as: a) the measurement of temperature when the controlling resistance is a temperature-sensitive element wound with nickel or platinum wire; b) the measurement of pressure when
11、 the controlling resistance is varied by means of a pressure-sensitive device connected in the pressure circuit; c) the measurement of angular or linear displacements when the controlling resistance is varied by the aircraft part, the position of which is to be indicated. 2 Definition For the purpos
12、es of this British Standard the term “ratiometer” shall denote an instrument having two circuits such that, for any one ratio of the currents in the two circuits, there shall be only one position of the pointer on the scale corresponding to this ratio. Section 1. General requirements 3 Preferred siz
13、e of case The instrument case should preferably be the British Standard aircraft instrument case, Type 2, specified in BS G 100, “General requirements for electrical equipment and indicating instruments for aircraft”. 4 Preferred units of measurement The units of measurement should preferably be in
14、accordance with BS A 22. “Units of measurement in civil aviation.” 5 General construction The instrument shall be sound and suitable for its purpose, and its design and construction shall comply with the relevant requirements of BS G 100. 6 Declaration of performance In addition to the declaration r
15、equired by BS G 100, the manufacturer shall state if the instrument will comply with the requirements for insulation resistance under climatic conditions only when the connections to the instrument are made by a sealed socket, itself sealed to the plug mounted on the instrument and to the sealed cab
16、le to which it is connected, or if, when an open type socket is used, provision has been made to seal the plug and socket combination against any ingress of moisture. The appropriate tests shall be made in accordance with this declaration. Section 2. Particular requirements 7 Construction a) The ins
17、trument shall consist of a ratiometer movement, having a scale graduated in terms of the physical quantity to be measured. If the instrument is required to indicate temperature, it shall be calibrated in accordance with the appropriate temperature/resistance characteristic given in Appendix A or App
18、endix B and the scale shall be suitably graduated for the range required. b) The instrument shall embody a means of ensuring that, in the event of failure of the electrical supply, the pointer shall take up an off-scale position. c) The moving element shall be accurately balanced. Provision shall be
19、 made for its re-balancing and for the secure locking of the means of adjustment against vibration. d) The pointer shall have freedom of movement beyond the ends of the scale. e) In addition to marking in accordance with the requirements of BS G 100, instruments intended for temperature measurement
20、shall be indelibly marked with the letters “Ni-law” or “Pt-law” adjacent to the electrical connections, according to the basis of their calibration. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 2 BSI 12-1999 Section 3. Test
21、s 8 General a) Tests shall be made to prove compliance with all the requirements of this British Standard. It is not intended or recommended that complete tests shall be made on every instrument supplied. Two kinds of test, therefore, are specified as follows: A. Type tests (Clauses 9 to 16), which
22、shall be made on representative samples of each particular design and range of instrument. B. Routine production tests (Clauses 17 and 18), which shall be made on every instrument manufactured in accordance with this British Standard. b) Minimum tests recommended to verify the serviceability of inst
23、ruments manufactured in compliance with this British Standard are indicated in Appendix C. c) The tests prescribed in Clauses 9 to 16 shall be performed in that order on the same instrument, except that another instrument may be used for the climatic test specified in Clause 15, provided it has been
24、 submitted previously to the endurance vibration test. d) Unless otherwise specified, the tests shall be made in an ambient temperature of 1520 C. The instrument shall be tested with the normal voltage, i.e. 28 volts for a 24-volt system and 112 volts for a 96-volt system, applied, and shall be conn
25、ected in accordance with the makers instructions, except that the sensing element may be replaced by a simulator calibrated in the quantities it is desired to measure, account being taken of the resistance of the leads. NOTEFor the purpose of the performance tests the expression “total scale range”
26、is defined as the algebraic difference of the scale end marks, i.e., the number of units indicated on the scale counted from one end to the other. A. Type tests 9 Position test When the nominal voltage is applied to the instrument and the pointer is at the mid-scale position, the departure from this
27、 mid-scale position, due to want of balance, shall not exceed 1 per cent of the total scale range when the instrument is moved in any direction within an angle of 90 from its normal position of use. 10 Ranging test At normal testing temperature and voltages, with dial upright and in a vertical plane
28、, the limit of error over the effective range, expressed as a percentage of the total scale range, shall be 2 per cent. 11 Friction test The error due to friction shall not exceed 2 per cent of the total scale range when the instrument is tested as follows: With the instrument dial upright in a vert
29、ical plane and the nominal voltage applied to the instrument terminals, the pointer shall be brought to the mid-point from one end of the scale by means of a continuously variable resistance in the ratiometer deflecting circuit (this resistance should be such that the pointer can be set gradually, w
30、ithout jerking, to the mid-scale position). This value of the resistance shall be noted. The pointer shall be deflected to the other extremity and gradually brought towards mid-scale, so that the final value of the resistance is equal to that previously noted. The linear deviation of the pointer fro
31、m its previous position, measured along the scale arc, should be noted. The friction error shall be taken as this distance expressed as a percentage of the length of the scale arc measured at the same radius and shall not exceed 2 per cent. 12 Voltage test For a voltage change throughout the range o
32、f the normal supply voltage plus 5 per cent, minus 25 per cent, the indication of the instrument shall not vary from that at the nominal supply voltage by more than 1.5 per cent. 13 Rotational acceleration test When the nominal voltage is applied and the pointer is at the mid-scale position, the ins
33、trument shall be subjected to a rotary sinusoidal oscillation of 45 amplitude about either side of the normal vertical position and with a total period of three seconds about the central axis of the instrument. The total amplitude of the oscillation of the pointer over the scale under these conditio
34、ns shall not exceed 5 per cent of the total scale range. 14 Temperature compensation test The variation in indication due to a change in the temperature of the instrument shall not exceed 0.03 per cent of the total scale range per degree Centigrade over the range 50 C. to 20 C., when tested under st
35、eady conditions of temperature. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 BSI 12-19993 15 Vibration, acceleration and climatic proofing tests a) The instrument shall be subjected to the grade of vibration, acceleration a
36、nd climatic tests specified in BS G 100 appropriate to the performance grading declared by the manufacturer. When the instrument is subjected to the vibration test the variation in indication due to pointer creep shall not exceed 1 per cent of the total scale range. b) The functioning tests specifie
37、d in the vibration, acceleration and climatic tests in BS G 100 shall each consist of a ranging test in accordance with Clause 10. 16 Insulation resistance The insulation resistance of the instrument shall comply with the requirements of BS G 100, Clauses 24.2 and 25.4. If the instrument terminals a
38、re in the form of a plug, the tests under conditions of humidity, temperature and pressure specified in Clause 25.4 shall be made with the corresponding socket and cable in place and securely tightened, provided that these parts, including the cable, are of a sealed form. If the plug and socket conn
39、ection is not fully sealed, provision shall be made to effect a sealed condition in order that any deficiencies in the connection shall not influence the results of the test. B. Routine production tests As defined in Clause 8 a) B. 17 Position, ranging and friction tests Each instrument shall satisf
40、actorily fulfil the requirements of the tests specified in Clauses 9, 10 and 11. 18 Insulation resistance test Insulation resistance shall be measured between insulated live parts and to earth at room temperature at a voltage of 500 volts D.C. After 15 seconds electrification the insulation resistan
41、ce shall be not less than 20 megohms Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114:1953 4 BSI 12-1999 Appendix A Temperature-resistance characteristics for nickel resistance thermometer elements Appendix B Temperature-resistance
42、characteristics for platinum resistance thermometer elements The resistance values shown in the following table are those which correspond to the standard platinum curve as defined for Class A resistance elements in BS 1904 “Commercial platinum resistance thermometer elements”. Rt = 90.0 + 0.438t +
43、0.0006t2 whereR = resistance in ohms. t = temperature in C. tRtR 80 70 60 58.80 62.28 65.88 40 50 60 108.48 113.40 118.44 50 40 30 69.60 73.44 77.40 70 80 90 123.60 128.88 134.28 20 10 0 81.48 85.68 90.00 100 110 120 139.80 145.44 151.20 10 20 30 94.44 99.00 103.68 130 140 150 157.08 163.08 169.20 1
44、60175.44 Standard curve and tolerances at bulb current of 1 mA. Rt = 130 (1 + 0.0039583t 0.000000583t2) where R = resistance in ohms. t = temperature in C. tRtRtR 100 90 80 77.67 83.00 88.30 100 110 120 180.70 185.69 190.66 300 310 320 277.55 282.24 286.90 70 60 50 93.58 98.83 104.07 130 140 150 195
45、.61 200.56 205.48 330 340 350 291.56 296.20 300.82 40 30 20 109.29 114.49 119.68 160 170 180 210.39 215.29 220.17 360 370 380 305.43 310.02 314.60 10 0 10 124.85 130.00 135.14 190 200 210 225.03 229.88 234.72 390 400 410 319.20 323.71 328.24 20 30 40 140.26 145.37 150.46 220 230 240 239.54 244.34 24
46、9.13 420 430 400 332.75 337.26 341.74 50 60 70 155.54 160.60 165.65 250 260 270 253.91 258.67 263.41 450 460 470 346.21 350.67 355.11 80 90 170.68 175.7 280 290 268.14 272.85 480 490 500 359.54 363.95 368.34 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled
47、 Copy, (c) BSI BS 2G 114:1953 BSI 12-19995 Appendix C Serviceability tests The minimum tests recommended to verify the serviceability of instruments manufactured in compliance with this British Standard are: a) Position test. Clause 9. b) Ranging test. Clause 10. c) Insulation resistance test. Claus
48、e 18. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2G 114: 1953 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents th
49、e UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which ca
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