1、BRITISH STANDARD BS 9720:1989 Incorporating Amendment No. 1 Specification for Custom-built transformers and inductors of assessed quality: generic data and methods of testBS9720:1989 This British Standard, having been prepared under the directionof the Electronic Components Standards PolicyCommittee
2、, was publishedunderthe authorityofthe Boardof BSIandcomes into effect on 31 October 1989 BSI 10-1999 First published September 1976 First revision 1983 Second revision October The following BSI references relate to the work on this standard: Committee reference ECL/18 Draft for comment 86/26525 DC
3、ISBN 0 580 17336 4 Committees responsible for this British Standard This British Standard was published under the direction of the Electronic Components Standards Policy Committee ECL/-. Its preparation was entrusted to Technical Committee ECL/18 upon which the following bodies were represented: Bri
4、tish Telecommunications plc Electronic Components Industry Federation Ministry of Defence National Supervising Inspectorate Power Supply Manufacturers Association (PSMA) Telecommunication Engineering and Manufacturing Association (TEMA) Amendments issued since publication Amd. No. Date of issue Comm
5、ents 6348 September 1991 Indicated by a sideline in the marginBS9720:1989 BSI 10-1999 i Contents Page Committees responsible Inside front cover Foreword v Section 1. General 1.1 Scope 1 1.2 Related documents 1 1.3 Definitions 1 1.4 Letter symbols, signs and abbreviations 4 1.5 Graphical symbols 4 1.
6、6 Marking of the component and package 4 1.7 Delayed delivery 4 1.8 Certified test records 4 1.9 Standard ratings and characteristics 4 1.10 Ordering information 5 Section 2. Tests 2.1 Test and measurement conditions 6 2.1.1 General 6 2.1.2 Measurement uncertainty 6 2.1.3 Alternative test methods 6
7、2.2 Visual inspection 6 2.2.1 General 6 2.2.2 Isolating screen position 6 2.2.3 Quality of solder joints (isolating screens) 6 2.3 Dimensioning and gauging procedure 7 2.4 Electrical test procedures 7 2.4.1 General 7 2.4.2 Winding resistance 7 2.4.2.1 D.C. winding resistance 7 2.4.2.2 Continuity 8 2
8、.4.3 Insulation resistance 8 2.4.3.1 Insulation resistance (standard atmosphere) 8 2.4.3.2 Insulation resistance (hot) 8 2.4.4 Losses 8 2.4.4.1 No-load current 8 2.4.4.2 No-load loss 9 2.4.5 Voltage proof (electric strength test) 9 2.4.6 Induced high voltage 9 2.4.7 Magnetic fields 10 2.4.7.1 Magnet
9、ic shielding 10 2.4.7.2 Magnetic influence (compass safe distance) 11 2.4.8 Inductance and a.c. resistance 12 2.4.9 Screens 12 2.4.9.1 Electrostatic screen(s) 12 2.4.9.2 Isolating screen 12 2.4.10 Q factor 12 2.4.11 Capacitance unbalance 13 2.4.12 Impedance unbalance 13 2.4.13 Voltage unbalance 14 2
10、.4.14 Resistance unbalance 14BS9720:1989 ii BSI 10-1999 Page 2.4.15 Leakage inductance 14 2.4.16 Capacitance 15 2.4.16.1 Self-capacitance 15 2.4.16.2 Interwinding capacitance 15 2.4.17 Voltage transformation ratio 15 2.4.18 Resonant frequency 15 2.4.18.1 Inherent self-resonance 15 2.4.18.2 Resonant
11、assemblies 16 2.4.19 Signal transfer characteristics 18 2.4.19.1 Insertion loss 18 2.4.19.2 Return loss 19 2.4.20 Frequency response 19 2.4.21 Pulse characteristics 19 2.4.22 Total harmonic distortion 20 2.4.23 Temperature rise 20 2.4.24 Voltage regulation at full load 20 2.4.25 Magnetic radiation 2
12、1 2.4.26 Acoustic noise 21 2.4.27 Polarity (phase) test 21 2.4.28 Non-linearity of magnetizing current 22 2.4.29 Maximum surface temperature 23 2.5 Environmental test procedures 23 2.5.1 General 23 2.5.2 Soldering 23 2.5.3 Robustness of terminations 23 2.5.4 Shock 23 2.5.5 Bump 23 2.5.6 Vibration 24
13、 2.5.7 Acceleration, steady state 24 2.5.8 Rapid change of temperature, thermal shock in air 24 2.5.9 Sealing 24 2.5.10 Climatic sequence 24 2.5.11 Damp heat, steady state 24 2.5.12 Dry heat 24 2.5.13 Mould growth 24 2.5.14 Salt mist 24 2.5.15 Sulphur dioxide 24 2.5.16 Flammability 24 2.5.17 Solvent
14、 resistance 24 2.6 Endurance test procedures 24 2.6.1 Short-term endurance (load run) 24 2.6.2 Long-term endurance (life test) 24 Section 3. Capability approval procedures 3.1 Eligibility for capability approval 26 3.2 Application for capability approval 26 3.2.1 General 26 3.2.2 Scope of capability
15、 26 3.2.2.1 General 26BS9720:1989 BSI 10-1999 iii Page 3.2.2.2 Environmental characteristics 26 3.2.2.3 Core type 26 3.2.2.4 Range of mass 26 3.2.2.5 Type of construction 26 3.2.2.6 Form of statement 26 3.2.3 Add-on and built-in components 26 3.3 Description of capability 27 3.4 Appraisal of capabil
16、ity 27 3.4.1 Capability qualifying components (CQCs) 27 3.4.2 CQC test schedules 27 3.4.2.1 General 27 3.4.2.2 Sample selection and test flow chart for the appraisal of capability 27 3.4.2.3 Failure procedure 28 3.4.3 Schedule 1: Preconditioning 30 3.4.4 Schedule 2A: Assessment of climatic durabilit
17、y 31 3.4.5 Schedule 2B: Assessment of long-term endurance 32 3.4.6 Schedule 2C: Assessment of mechanical/environmental durability 32 3.4.7 Schedule 3: Selective assessment of mechanical/environment durability 34 3.5 Announcement of capability approval 35 3.6 Maintenance of capability approval 35 3.6
18、.1 General 35 3.6.2 Annual testing 36 3.6.3 Three-yearly testing 36 3.6.4 Additional boundaries to the approval 36 3.6.5 Procedure in the event of failure 36 3.7 Quality conformance inspection 36 3.8 Changes to the approved capability 36 Appendix A Allocation of numbers to generic, sectional and bla
19、nk detail specifications 38 Appendix B Sample format for certified test record 38 Appendix C Sample format for abstract of manufacturers report 39 Appendix D List of clauses corresponding to those in BS 9720:1983 39 Index 44 Figure 1 Pulse waveform parameters 3 Figure 2 Examples of good solder joint
20、s 6 Figure 3 Examples of poor solder joints 7 Figure 4 Helmholtz structure 11 Figure 5 Measurement of capacitance unbalance 13 Figure 6 Measurement of impedance unbalance 14 Figure 7 Measurement of voltage transformation ratio 16 Figure 8 Measurement of resonant frequency: Inherent self-resonance 17
21、BS9720:1989 iv BSI 10-1999 Page Figure 9 Measurement of resonant frequency: resonant assemblies 17 Figure 10 Measurement of insertion loss and frequency response 18 Figure 11 Use of two identical transformers when transformation ratio is not unity 19 Figure 12 Measurement of non-linearity of magneti
22、zing current 22 Figure 13 Maximum non-linearity of magnetizing current 23 Figure 14 Sample selection and test flow chart for the appraisal of capability 29 Figure 15 Sample selection and test flow chart for the maintenance of capability approval 37 Table 1 Preferred values of acceleration and displa
23、cement for vibration testing 5 Table 2 Proof test voltages 9 Table 3 Data for magnetic radiation test 21BS9720:1989 BSI 10-1999 v Foreword This revision of BS 9720 has been prepared under the direction of the Electronic Components Standards Policy Committee: it supersedes BS9720:1983, which is withd
24、rawn. This edition incorporates technical changes to the previous text as well as new material whose purpose is primarily to clarify both tests and procedures. This standard is a generic specification for use in the BS9000 scheme for electronic components of assessed quality. It includes the general
25、 information, terminology and methods of test required for the assessment of the performance of transformers and inductors. Because such components are usually manufactured to comply with a particular customers order, the capability approval procedure is invoked in accordance with clause15 of BS9000
26、-1:1981 and BS9005, and the standard therefore contains the appropriate capability approval test schedules and requirements. For convenience, the following outline of the sequence of events in the capability approval procedure is given. a) A manufacturer wishing to obtain capability approval writes
27、a “capability manual”, which clearly defines the scope of his design capability, manufacturing processes and quality control, to the satisfaction of the National Supervising Inspectorate (NSI). b) The manufacturer in collaboration with the NSI selects sample components to demonstrate the limits of t
28、his scope, and the sample is assessed. c) These components are submitted to a test programme in accordance with section3 of this standard. d) When testing is successfully completed and the manufacturers systems approved against the capability manual, capability approval is granted and the fact publi
29、shed in PD 9002. The capability approval is maintained by periodic testing of sample components at the limits of the scope of their capability. e) A potential customer makes an enquiry to the manufacturer for a component within the scope of capability published in PD9002 (or by CODUS). f) The specif
30、ication is negotiated between the manufacturer and the customer until an agreed customers detail specification (based on one of the blanks included in the appropriate sectional specification (seeAppendix A) is finalized. g) The manufacturer allocates a reference number to the resulting detail specif
31、ication which is filed and is available for scrutiny by the NSI. The component is inspected and released in accordance with this detail specification. BS 9720:1989, from the point of view of system users, differs from BS9720:1983 in details of the capability approval (CA) procedures, the most signif
32、icant of which is the elimination of quarterly testing for the maintenance of CA. The portfolio of test procedures is substantially the same, even though some of the test procedures have been amended. It is expected that those seeking approval to the BS9720 CA procedure would take advantage of the l
33、atest published generic specification: however, the existing and current sectional specifications refer to tests listed in BS9720:1983, and the reference numbers to these tests in BS9720:1989 have changed. Appendix D contains a list giving the necessary correspondences between these reference number
34、s for the convenience of users of these sectional specifications.BS9720:1989 vi BSI 10-1999 This standard calls for the use of substances and/or test procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and in no way absolves eithe
35、r the supplier or the user from statutory obligations relating to health and safety at any stage of manufacture or use. 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
36、 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 to vi, pages1to 45 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. Thi
37、s will be indicated in the amendment table on the inside front cover.BS9720:1989 BSI 10-1999 1 Section 1. General 1.1 Scope This British Standard specifies the requirements that manufacturers of custom-built transformers and inductors need to comply with in order to achieve and maintain capability a
38、pproval to BS9000, and the component test schedules to be used for the assessment of that capability. It applies to components, including polyphase types, that are primarily intended for use in electronic equipment. This standard also specifies marking requirements and related symbols and terminolog
39、y; and describes the methods of test for transformers and inductors that are required by the relevant sectional specifications (which contain the customers blank detail specification), and the schedules for the assessment and maintenance of capability. NOTE 1The transformers and inductors that are t
40、he subject of this specification may include other components essential to the operation of the device, e.g.capacitors associated with constant voltage transformers and resonated windings. NOTE 2This standard should be read in conjunction with BS9000 and BS9005; such general details and definitions
41、given in those standards as are appropriate to this standard should be held to be part of this standard unless otherwise stated herein. NOTE 3The allocation of numbers to generic sectional and blank detail specifications in the9700 series is given in Appendix A. 1.2 Related documents BS 171, Power t
42、ransformers Part 4: Specification for tappings and connections. BS 2011, Basic environmental testing procedures. BS 3939, Guide for graphical symbols for electrical power, telecommunications and electronics diagrams. BS 4727, Glossary of electrotechnical, power, telecommunication, electronics, light
43、ing and colour terms. BS 5775, Specification for quantities, units and symbols. BS 5938, Cores for inductors and transformers for telecommunications Part 1: Methods of measurement. BS 5969, Specification for sound level meters. BS 6001, Sampling procedures for inspection by attributes. BS 9000, Gene
44、ral requirements for a system for electronic components of assessed quality Part1:Specification of basic rules and procedures. BS 9005, Specification for general procedures to be followed for the capability approval of electronic components covered by BS9000-1. NOTE 1Other standards concerned with q
45、uality assessment procedures for transformers and inductors for electronic equipment are listed inAppendix A. PD 9002, BS 9000 component selection guide. NOTE 2Information in this publication may also be accessed by subscribers to CODUS Limited via their computer terminals. CODUS Limited, Institute
46、for Information Technology, is at196-198 West Street, Sheffield S14ET. British Standard G 118, Specification for aircraft magnetic compass, direct-reading. 1.3 Definitions For the purposes of this British Standard the following definitions apply, together with those given in BS4727. 1.3.1 component
47、a transformer or inductor in accordance with this specification 1.3.2 sealed components components designed to prevent ingress of moisture, etc., under arduous climatic conditions. This includes components enclosed in a hermetically sealed can or encapsulated in a manner that may or may not include
48、the core 1.3.3 non-sealed components components other than sealed components 1.3.4 peak working voltage the maximum instantaneous voltage for which the winding is rated under working circuit conditions 1.3.5 pulse waveform parameters (see Figure 1) 1.3.5.1 peak pulse amplitude the maximum value of a
49、 smooth curve through the top of the pulse, excluding any initial “spike” or “overshoot” the duration of which is less than10% of the pulse duration 1.3.5.2 pulse duration the time interval between the first and last instants at which the pulse amplitude equals50% of the peak pulse amplitude 1.3.5.3 pulse rise time the interval between the first instant at which the pulse amplitude reaches10% of the peak pulse amplitude and the first instant at which the pulse amplitude reaches90% of the peak pulse amplitude, excluding any unwanted
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