1、BRITISH STANDARD AEROSPACE SERIES BS 2G 127:1967 Specification for Power and current transformers for use in aircraft electrical power supply systems UDC 629.13.066:621 314.2BS 2G 127:1967 This British Standard, having been approved by the AerospaceIndustry StandardsCommittee and endorsed by the Cha
2、irman of theEngineering Divisional Council, was published under theauthority of the General Council of the Institution on 29December1967 BSI 01-2000 The following BSI references relate to the work on this standard. Committee reference ACE/45 Draft for comment 66/3882 ISBN 0 580 34131 3 Amendments is
3、sued since publication Amd. No. Date CommentsBS 2G 127:1967 BSI 01-2000 i Contents Page Foreword ii 1 Scope 1 2 Definitions 1 3 Construction 1 4 Rating 1 5 Supply characteristics 1 6 Efficiency and regulation 1 7 Surges 1 8 Voltage balance 1 9 Environmental conditions 2 10 Arrangement and constructi
4、on 2 11 Terminals 2 12 Acoustic noise 2 13 Compass interference 2 14 Cooling 2 15 Declarations 3 16 Marking 3 17 Tests general 3 18 Type tests 3 19 Production acceptance tests 9 20 Production quality tests 10 Appendix A Climatic test schedule 11 Figure 1 Measuring device for dust and sand tests 13 T
5、able 1 4BS 2G 127:1967 ii BSI 01-2000 Foreword This revision of BS G127:1950 has been based upon Ministry of Aviation Specification EL.2018, Issue B. It is intended to be used in conjunction with individual specifications for particular designs of transformer. Reference is made in the standard to th
6、e following: BS 2G 100, General requirements for electrical equipment and indicating instruments for aircraft 1) . BS G 178, Crimped joints for general purpose aircraft electrical cables. BS SP 20, Panel type air filter elements for use with internal combustion engines and compressors on aircraft. B
7、S 89, Electrical indicating instruments. BS 171, Power transformers. BS 205, Glossary of terms used in electrical engineering. BS 822, Terminal markings for electrical machinery and apparatus Part3:Terminal markings for power transformers. BS 3489, Sound level meters (industrial grade). NOTEThe figu
8、res in British units are to be regarded as the standard. Metric conversions are approximate. More accurate conversions should be based on the tables in BS350, “Conversion factors and tables”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British
9、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 document comprises a front cover, an inside front cover, pages i and ii, pages1 to 13 and a back cover. This standard has been
10、updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) References to BS 2G 100-3 relate to the draft revision of that part (D65/11997).BS 2G 127:1967 BSI 01-2000 1 1 Scope This British Standard states the gen
11、eral design and test requirements for power transformers of25VA rating and larger and for current transformers for use in aircraft electrical power supply systems. It is intended to apply to single-phase, three-phase or Scott connected transformers used in distribution, load sharing and protective c
12、ircuits etc., but not to transformers specifically designed for use in electronic equipment. 2 Definitions For the purpose of this British Standard the definitions in BS205 apply. 3 Construction 3.1 The design and construction of the transformer shall comply with the relevant requirements of BS2G 10
13、0 and of the individual specification. 3.2 Unless otherwise required by the individual specification, the transformer shall be suitable for operation at altitudes up to60000ft(18300m), and over a temperature range of65 C to70 C. For special applications operation at temperatures up to125 C may be re
14、quired. 4 Rating 4.1 Transformers for general applications shall be rated with a unity power factor load at sea level and at a temperature of70 C, with no thermal conductance through the mountings. Transformers designed to be force-cooled shall also be subjected, whilst being rated, to the appropria
15、te conditions of air flow specified in the individual specification. 4.2 For transformers for special applications the rating conditions, ambient temperature, altitude and cooling, shall be as specified in the individual specifications with any thermal conductance through the mountings taken into ac
16、count when this can be defined. 4.3 If a transformer rated for general purposes is to be used for a specific application it will be necessary to repeat some of the rating tests under the relevant conditions in order to check its suitability for the particular application. 4.4 The rating under the mo
17、st adverse combination of pressure and temperature conditions shall be declared. 5 Supply characteristics 5.1 Power transformers shall be designed to operate from the constant frequency or variable frequency a.c.power supply specified in BS 2G100-3. Theparticular supply applicable shall be stated in
18、 the individual specification. 5.2 It cannot be assumed that the maximum frequency will necessarily occur at the maximum voltage, or that the minimum frequency will occur at the minimum voltage. 5.3 The transformer shall be capable of withstanding and operating under the conditions oftransient and o
19、ver voltage input indicated by the appropriate curves in BS 2G100-3. 6 Efficiency and regulation Unless otherwise stated in the individual specification, power transformers shall have an efficiency of at least90% on full load, and a voltageregulation (hot) of not more than3%. NOTEVoltage regulation
20、(hot) is the difference between the no-load secondary voltage with the windings at room temperature and the full-load secondary voltage with the windings at maximum temperature, expressed as a percentage of the no-load secondary voltage with the windings at room temperature. 7 Surges 7.1 Unless the
21、inrush current characteristics of the transformer are such that a fuse of rating2amp or less will not be ruptured, the maximum peak value of inrush current of the transformer shall be declared with itsI 2 t value. 7.2 Power transformers shall also be designed to withstand without damage the voltage
22、surges induced when they are switched off line with their loads disconnected. 8 Voltage balance 8.1 For three-phase transformers the difference between line to line voltages, and the difference between line to neutral voltages, shall not exceed2% of their nominal values, when tested using balanced n
23、ominal input voltages and balanced loads at all values between half full load and full load.BS 2G 127:1967 2 BSI 01-2000 9 Environmental conditions 9.1 The transformer shall comply with the requirements of BS2G100-2 in respect of: 9.2 If required by the individual specification, the transformer shal
24、l also comply with the requirements of18.15, 18.16 and18.17 of this British Standard in respect of resistance to salt corrosion, dust and sand, and contaminating fluids, and with the requirements of BS2G 100-2 in respect of: 1) Waterproofness: Grade B 2) Resistance to fire 3) Explosion proofness: to
25、 the category stated in the individual specification. 10 Arrangement and construction 10.1 There should be no limitation in the performance of the transformer in respect of the attitude in which it may be mounted. Any such limitations shall be declared. 10.2 The mounting arrangements for the transfo
26、rmer shall be such that its satisfactory operation is not affected under the specified conditions of vibration, acceleration and temperature variation. 10.3 Transformers bearing the same manufacturers identification number shall be interchangeable mechanically and electrically. 10.4 The design and c
27、onstruction of the transformer should be such that it is suitable for1000hours operation at maximum operating temperature, and for an operating life of30000hours at25 C. 10.5 Transformers shall be designed to operate from a fully insulated system and the windings shall be insulated from the frame. I
28、n3-phase star connected arrangements the neutral point shall be brought out to an insulated terminal, unless otherwise required by the individual specification. 10.6 If an electrostatic screen is required, this shall be stated in the individual specification. In transformers with electrostatic scree
29、ns provision shall be made for earthing the core. 10.7 The maximum temperature of the external surface of the transformer whilst in operation shall be declared (see18.5.1.1). 11 Terminals 11.1 Screwed terminals, having Unified threads unless otherwise agreed by the Design Authority, shall be provide
30、d for external connections. They shall be designed in accordance with the requirements of BS2G100-1, and shall accommodate cable terminations of appropriate design of a rating adequate for the current and temperature to be carried, and crimped to the cables in accordance with the requirements of BSG
31、178. 11.2 The terminals shall be clearly and indelibly marked to identify the associated windings, in accordance with the requirements of BS822-3. 12 Acoustic noise 12.1 Unless otherwise specified the noise emitted by the transformer, when measured in accordance with18.10, shall not exceed the follo
32、wing limits: 13 Compass interference 13.1 The transformer shall be designed so that the external magnetic fields produced are as small as practicable. The compass safe distance, measured in accordance with BS2G100-2, shall be declared by the manufacturer. 14 Cooling 14.1 The transformer shall have a
33、dequate cooling facilities so that continuous operation at full load is possible at ground level at the maximum operating ambient temperature. The temperature conditions required at altitude will depend on the particular application, and will be stated in the individual specification. 14.2 For self-
34、cooled, including fan-cooled, transformers the manufacturer shall supply curves indicating the limiting altitude for various ambient air temperatures when the transformer is supplying full load at nominal input voltage. 14.3 For force-cooled transformers curves shall be supplied showing the mass flo
35、w and pressure head of cooling air required for various inlet air temperatures at ground level,30000ft(9150m) and60000ft(18300m) and with the transformer supplying full load at nominal input voltage. 14.4 Information shall be provided on the installation drawings about the minimum clearances of the
36、air exhaust and the quantity and head of air required for force-cooled transformers. 1) Vibration: Grade A, unless otherwise specified 2) Normal acceleration: Grade D, Class 1 (A) (i) 3) Crash acceleration: Grade F, Class 11 4) Climatic proofness: Class 1, unless otherwise specified. Transformer rat
37、ing Noise level dB Below 1 kVA 60 1 kVA and above 75BS 2G 127:1967 BSI 01-2000 3 15 Declarations 15.1 In addition to the relevant declarations required by BS2G100, the following information shall be provided by the manufacturer: 1) Rating at70 C unless otherwise required by the individual specificat
38、ion. 2) Rated input voltage and vector group symbol ifapplicable (see BS171; Section 14); frequency of the supply or, for current transformers, current ratio and rated burden. 3) Maximum temperature of external surface. 4) Maximum inrush current. 5) Cooling requirements. 16 Marking 16.1 The followin
39、g information shall be indelibly marked on the nameplate, and the modification plate shall provide for modification references: 1) Manufacturers name 2) Manufacturers type (or part) number 3) Serial (or batch) number 4) Any other information required by the individual specification. 17 Tests general
40、 17.1 Tests shall be made to prove compliance with all requirements of this British Standard. It is not intended or recommended that complete tests shall be made on every transformer supplied. Three kinds of tests, therefore, are specified as follows: 1) Type tests (18.1 to18.19) which shall be made
41、 on each particular type of transformer. 2) Production acceptance tests (19.1 to19.6) which shall be made on every transformer manufactured to this British Standard. 3) Production quality tests (20.2) which shall be made on samples selected as specified in20.1. 17.2 Transformers subjected to type te
42、sts shall have passed the production acceptance tests, and the results shall be recorded. 17.3 The Inspecting Authority shall be provided with complete manufacturing drawings of the transformer before samples are submitted for approval. The manufacturer shall disclose to the Approving Authority 2)an
43、y proposal to introduce changes affecting interchangeability and shall obtain the Approving Authoritys written approval before applying the change to production. As soon as series production commences a complete set of drawings shall be sent to the Inspecting Authority. 17.4 Unless otherwise stated,
44、 all tests shall be made under normal laboratory conditions, i.e.: except that, during the prescribed periods of recovery after the humidity, temperature and pressure cycling and the tropical exposure sections of the climatic tests (see18.11), the relative humidity shall be controlled to75 2% 17.5 D
45、uring the tests the transformer shall be energized from a supply complying with BS2G100-3. 17.6 Meters used for measuring voltage, frequency and input current shall be to an accuracy not less than that specified for precision grade instruments in BS89:1954. 17.7 Unless otherwise required by the indi
46、vidual specification, every transformer shall be tested at its rated input voltage and frequency, and, if the primary winding is tapped, the tapping used shall be the mean of those available. The actual values ofthe rated voltage and frequency will be stated in the individual specification together
47、with details of the load currents to be used for testing and all permissible tolerances not already given in this specification. The figures given for voltage and current are to be r.m.s. values. 18 Type tests 18.1 General 18.1.1 For the purpose of type testing, one or twosamples (to economise on te
48、sting time), as appropriate (see18.1.2) of each basic type of transformer shall be inspected and tested as indicated inTable 1. The tests to be made on variant types of transformer, as defined below, shall be agreed with the Approving Authority. The tests shall be made in the order shown inTable 1.
49、18.1.1.1 Basic type. An original design of transformer with a given core size, construction, insulation system and input voltage and frequency. 18.1.1.2 Variant type. A transformer differing from the basic type only as regards the winding, terminations and minor details of construction. 2) For equipment for British civil and military aircraft, the Approving Authorities are the Air Registration Board or the Ministry of Technology respectively (through a design authority approved by them). 1)Temperature: 20 5 C 2)Relative humidity: not more than80% 3)Atmospheri
