1、BRITISH STANDARD BS 2G114: 1953 Specification for Direct current ratiometer indicators for aircraft UDC 629.13.05:621.317.085BS2G114:1953 This British Standard, having been approved by the Aircraft Industry Standards Committeeand endorsed by theChairman of the EngineeringDivisional Council,was publi
2、shed undertheauthorityof the GeneralCouncil ofthe Institutionon 19 November 1953 BSI 12-1999 ISBN 0 580 34130 5 Foreword This revised British Standard includes data relating to platinum resistance thermometer elements in addition to that given in BSG114:1949, for nickel resistance thermometer elemen
3、ts. An Appendix has been added, giving information on minimum tests recommended to verify the serviceability of instruments manufactured in compliance with the requirements of the standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British St
4、andards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 5 and a back cover. This standard has been up
5、dated (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 Amd. No. Date CommentsBS2G114:1953 BSI 12-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 Definition 1 Sectio
6、n 1. General requirements 3 Preferred size of case 1 4 Preferred units of measurement 1 5 General construction 1 6 Declaration of performance 1 Section 2. Particular requirements 7 Construction 1 Section 3. Tests 8 General 2 9 Position test 2 10 Ranging test 2 11 Friction test 2 12 Voltage test 2 13
7、 Rotational acceleration test 2 14 Temperature compensation test 2 15 Vibration, acceleration and climatic proofing tests 3 16 Insulation resistance 3 17 Position, ranging and friction tests 3 18 Insulation resistance test 3 Appendix ATemperature-resistance characteristics for nickelresistancethermo
8、meter elements 4 Appendix B Temperature-resistance characteristics for platinumresistancethermometer elements 4 Appendix C Serviceability tests 5ii blankBS2G114:1953 BSI 12-1999 1 1 Scope This British Standard specifies the requirements for direct current ratiometer indicators for applications on ai
9、rcraft 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 the controlling resistance is varied by means of a pressure-sensitive device connected in the pressure circuit;
10、 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 purposes of this British Standard the term “ratiometer” shall denote an instrument having two circuits such that, for
11、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 size of case The instrument case should preferably be the British Standard aircraft instrument case, Type2, specifi
12、ed in BSG100, “General requirements for electrical equipment and indicating instruments for aircraft”. 4 Preferred units of measurement The units of measurement should preferably be in accordance with BSA 22. “Units of measurement in civil aviation.” 5 General construction The instrument shall be so
13、und and suitable for its purpose, and its design and construction shall comply with the relevant requirements of BSG100. 6 Declaration of performance In addition to the declaration required by BSG100, the manufacturer shall state if the instrument will comply with the requirements for insulation res
14、istance 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 cable to which it is connected, or if, when an open type socket is used, provision has been made to seal the plug and socke
15、t 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 instrument shall consist of a ratiometer movement, having a scale graduated in terms of the physical quantity to be measure
16、d. If the instrument is required to indicate temperature, it shall be calibrated in accordance with the appropriate temperature/resistance characteristic given inAppendix A orAppendix B and the scale shall be suitably graduated for the range required. b) The instrument shall embody a means of ensuri
17、ng 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 made for its re-balancing and for the secure locking of the means of adjustment against vibration. d) The pointer shall h
18、ave freedom of movement beyond the ends of the scale. e) In addition to marking in accordance with the requirements of BSG100, instruments intended for temperature measurement shall be indelibly marked with the letters “Ni-law” or “Pt-law” adjacent to the electrical connections, according to the bas
19、is of their calibration.BS2G114:1953 2 BSI 12-1999 Section 3. Tests 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,
20、 are specified as follows: A. Type tests (Clauses9 to16), which shall be made on representative samples of each particular design and range of instrument. B. Routine production tests (Clauses17 and18), which shall be made on every instrument manufactured in accordance with this British Standard. b)
21、Minimum tests recommended to verify the serviceability of instruments manufactured in compliance with this British Standard are indicated inAppendix C. c) The tests prescribed in Clauses9 to16 shall be performed in that order on the same instrument, except that another instrument may be used for the
22、 climatic test specified in Clause15, provided it has been submitted previously to the endurance vibration test. d) Unless otherwise specified, the tests shall be made in an ambient temperature of1520 C. The instrument shall be tested with the normal voltage, i.e.28volts for a24-volt system and112vo
23、lts for a96-volt system, applied, and shall be connected 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 pe
24、rformance tests the expression “total scale range” 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
25、 at the mid-scale position, the departure from this mid-scale position, due to want of balance, shall not exceed1percent of the total scale range when the instrument is moved in any direction within an angle of90 from its normal position of use. 10 Ranging test At normal testing temperature and volt
26、ages, with dial upright and in a vertical plane, the limit of error over the effective range, expressed as a percentage of the total scale range, shall be2per 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 follow
27、s: With the instrument dial upright in a vertical 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
28、such that the pointer can be set gradually, without 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 n
29、oted. The linear deviation of the pointer from 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 exceed2percent. 12 Voltage test F
30、or a voltage change throughout the range of the normal supply voltage plus5percent, minus25percent, the indication of the instrument shall not vary from that at the nominal supply voltage by more than1.5percent. 13 Rotational acceleration test When the nominal voltage is applied and the pointer is a
31、t the mid-scale position, the instrument shall be subjected to a rotary sinusoidal oscillation of45 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 ove
32、r the scale under these conditions shall not exceed5percent 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 exceed0.03percent of the total scale range per degree Centigrade over the range 50 C. to20
33、 C., when tested under steady conditions of temperature.BS2G114:1953 BSI 12-1999 3 15 Vibration, acceleration and climatic proofing tests a) The instrument shall be subjected to the grade of vibration, acceleration and climatic tests specified in BSG 100 appropriate to the performance grading declar
34、ed by the manufacturer. When the instrument is subjected to the vibration test the variation in indication due to pointer creep shall not exceed1percent of the total scale range. b) The functioning tests specified in the vibration, acceleration and climatic tests in BSG 100 shall each consist of a r
35、anging test in accordance with Clause10. 16 Insulation resistance The insulation resistance of the instrument shall comply with the requirements of BSG 100, Clauses24.2 and25.4. If the instrument terminals are in the form of a plug, the tests under conditions of humidity, temperature and pressure sp
36、ecified in Clause25.4 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 connection is not fully sealed, provision shall be made to effect a sealed condition in order that
37、 any deficiencies in the connection shall not influence the results of the test. B. Routine production tests AsdefinedinClause8 a) B. 17 Position, ranging and friction tests Each instrument shall satisfactorily fulfil the requirements of the tests specified in Clauses9, 10 and11. 18 Insulation resis
38、tance test Insulation resistance shall be measured between insulated live parts and to earth at room temperature at a voltage of500volts D.C. After15seconds electrification the insulation resistance shall be not less than20megohmsBS2G114:1953 4 BSI 12-1999 Appendix A Temperature-resistance character
39、istics for nickel resistance thermometer elements Appendix B Temperature-resistance 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
40、BS1904 “Commercial platinum resistance thermometer elements”. R t= 90.0 + 0.438t + 0.0006t 2 where R = resistance in ohms. t = temperature in C. t R t R 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
41、 120 139.80 145.44 151.20 10 20 30 94.44 99.00 103.68 130 140 150 157.08 163.08 169.20 160 175.44 Standard curve and tolerances at bulb current of1mA. R t= 130 (1 + 0.0039583t 0.000000583t 2 ) where R = resistance in ohms. t = temperature in C. t R t R t R 100 90 80 77.67 83.00 88.30 100 110 120 180
42、.70 185.69 190.66 300 310 320 277.55 282.24 286.90 70 60 50 93.58 98.83 104.07 130 140 150 195.61 200.56 205.48 330 340 350 291.56 296.20 300.82 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.
43、72 390 400 410 319.20 323.71 328.24 20 30 40 140.26 145.37 150.46 220 230 240 239.54 244.34 249.13 420 430 400 332.75 337.26 341.74 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 90 170.68 175.7 280 290 268.14 272.85 480 490 500 359.54 363.95 368.3
44、4BS2G114:1953 BSI 12-1999 5 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. Clause9. b) Ranging test. Clause10. c) Insulation resistance test. Clause18.BS 2G114: 195
45、3 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards ar
46、e updated by amendment or revision. Users of BritishStandards 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 Br
47、itishStandard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel:02089969000. Fax:02089967400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the late
48、st editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel:02089969001. Fax:02089967001. In response to orders for international standards, it is BSI policy to supply the BSI implementation of those th
49、at have been published as BritishStandards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel:02089967111. Fax:02089967048. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the
