1、BRITISH STANDARD BS 9721:1985 Sectional specification for signal transformers of assessed quality for use in electronic equipment for capability approval UDC 621.372.512.24BS9721:1985 This British Standard, having been prepared under the directionof the Electronic Components Standards Committee, was
2、 published underthe authority of the BoardofBSI and comes intoeffecton 30September1985 BSI 01-2000 First published April 1978 First revision September 1985 The following BSI references relate to the work on this standard: Committee reference ECL/18 Draft for comment 82/27652 DC ISBN 0 580 14379 1 Co
3、mmittees responsible for this BritishStandard The preparation of this British Standard was entrusted by the Electronic Components Standards Committee (ECL/-) to Technical Committee ECL/18, upon which the following bodies were represented: BEAMA Transmission and Distribution Association Electronic Co
4、mponents Industry Federation Electronic Engineering Association Engineering Equipment and Materials Users Association Ministry of Defence National Supervising Inspectorate Society of British Aerospace Companies Limited Telecommunications Engineering and Manufacturing Association (TEMA) UnitedKingdom
5、 Atomic Energy Authority Amendments issued since publication Amd. No. Date of issue CommentsBS9721:1985 BSI 01-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Related documents 1 3 Preparation of the detail specification 1 4 Inspection requirements to be listed
6、 in the detail specification 2 5 Detail specification 2BS9721:1985 ii BSI 01-2000 Foreword This revised British Standard has been prepared under the direction of the Electronic Components Standards Committee. It is intended to be used for the preparation of detail specifications for signal transform
7、ers released under the terms of the BS9000/BS9720 capability approval procedure. In this edition the format of the blank detail specification has been simplified and the recommended test schedule modified, to accord with the experience gained in operating the procedure since the first edition, and c
8、lear guidance is given on the suitable test inspection levels. Changes brought about by the revision of BS9720 are also incorporated where appropriate. As an assessment level for the document is now inappropriate, this standard supersedes both BS9721:1978 and BS9722:1978, which are withdrawn. It is
9、intended for use by the following originators. a) A customer wishing to procure signal transformers that are within the scope of the approved capability of his supplying component manufacturer, e.g.for customers detail specifications (CDSs). b) A capability approved manufacturer of signal transforme
10、rs wishing to prepare specifications for his own products which are within the scope of his capability approval. 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 Brit
11、ish 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 10 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wil
12、l be indicated in the amendment table on the inside front cover.BS9721:1985 BSI 01-2000 1 1 Scope This British Standard specifies inspection requirements and tests from which a selection is made when preparing a detail specification for signal transformers to be released under the terms of BS9720 ca
13、pability approval. It includes a blank detail specification (BDS), which shows the format, and indicates which tests are considered to be appropriate to this type of component; although the final selection of tests to be included in the inspection schedule is at the discretion of the specification w
14、riter. It also lists appropriate ratings and characteristics. The components covered by this standard are essentially concerned with uni-directional and bi-directional transfer of signals (information) from one section of a circuit to another. These signals may have some power content and may cover
15、a band of frequencies. 2 Related documents BS 2011, Basic environmental testing procedures. BS 6001, Sampling procedures and tables for inspection by attributes. BS 9000, General requirements for a system for electronic components of assessed quality. BS 9720, Specification for custom-built transfor
16、mers and inductors of assessed quality: generic data and methods of test. PD 9002, BS 9000 and BS CECC qualified products list. NOTEBS 6001 and BS9720 should be available for reference when preparing detail specifications. 3 Preparation of the detail specification 3.1 General A detail specification
17、shall be prepared in accordance with2.6.1 of BS9720:1983. NOTE 1The detail specification takes the form of the BDS shown in clause5, particularly in respect of the front page format and, in principle, in respect of the presentation of the inspection requirements. NOTE 2All the tests shown in the BDS
18、 are taken from BS9720. Those shown in bold type concern operating characteristics of fundamental importance and it is strongly recommended that these are selected by the specification writer for inclusion in the detail specification. The tests shown in plain type are listed for the convenience of t
19、he specification writer, and tests should be selected from them according to the particular application of the component. NOTE 3Over-specification may carry an economic penalty. However, the specification writer may specify tests and sampling levels different from, less than, or additional to those
20、given in the BDS. 3.2 Particular requirements 3.2.1 Where additional tests of a type not defined or invoked in BS9720 are required, these shall be fully specified in the detail specification. 3.2.2 Any tests considered as being destructive shall be so denoted in the test schedule by the addition of
21、the notation “(D)”. NOTEThe use of this notation is not illustrated in the BDS. 3.2.3 Tests shall be grouped in the schedule according to the level of sampling required and, where indicated see4.1 b), in the order of testing required. Where100% testing is not required, inspection levels and acceptab
22、le quality levels shall be selected from BS6001. 3.2.4 The completed detail specification shall be allocated a component identity number and issue status by the originator. NOTE 1This number is chosen by the originator (manufacturer or customer) within his own system. It is thus not subject to any e
23、xternal rules or codification. NOTE 2In the special case of a manufacturers detail specification for a standard catalogue item which the manufacturer wishes to be listed in PD9002, BSI will allocate an appropriate number in accordance with15.11 of BS9000-1:1981. 3.2.5 Additionally the detail specifi
24、cation shall include a number allocated by the component manufacturer comprising this specification number, his factory identification code letters and a unique number within his registration system, e.g.BS9721/XYZ/1234. NOTEAfter a detail specification has been allocated the manufacturers reference
25、 number in accordance with3.2.5, it is to be considered a contractual part of an order. Copies of all such detail specifications are to be retained by the manufacturers chief inspector. 3.3 Ratings and characteristics 3.3.1 Ratings. In the case of customer originated detail specifications, customer
26、and manufacturer agreement shall be obtained on the ratings to be ascribed to the component in the detail specification. These ratings shall not exceed the scope of the manufacturers capability approval (see also1.1.12 of BS9720:1983). 3.3.2 Characteristics. A customer shall prescribe in the detail
27、specification any characteristic required for a component. 3.4 Outline drawings and winding schematic diagram 3.4.1 The detail specification shall incorporate a drawing of the transformer showing important features, such as those dimensions affecting interchangeability, restrictions on mounting and
28、marking requirements.BS9721:1985 2 BSI 01-2000 3.4.2 The detail specification shall incorporate a schematic diagram showing all windings, screens, taps and phasings and giving termination identification. 4 Inspection requirements to be listed in the detail specification 4.1 Conformance inspection Th
29、e detail specification shall incorporate the following notes. a) Sampling inspection is to be carried out in accordance with BS6001, normal inspection. b) Tests in a group may be carried out in any order except where otherwise indicated (see3.2.3). c) Components submitted to any tests marked (D) may
30、 not be released under BS9720 capability approval. (D = destructive) d) The values given for measurement limits are absolute values: measurement uncertainty is to be taken into account. 4.2 Design verification The tests to be detailed under this heading are those which the specification writer consi
31、ders to be inappropriate to lot-by-lot release, but appropriate to the verification of new and original designs. Accordingly, they are to be performed only when specifically so stated in the order, and the detail specification shall carry a statement to this effect. If design verification is require
32、d, the number of specimens and that there shall be no failures shall be stated in the detail specification. NOTETwo specimens will normally be required. 5 Detail specification The BDS which follows, when completed in accordance with clause3, forms the relevant detail specification. NOTEThe front pag
33、e of the BDS has been based upon the need for a customers detail specification. Where a manufacturers detail specification is required, some changes will be necessary, but the basic format should be retained.BS9721:1985 BSI 01-2000 3 Blank detail specification Sheet 1 (of 8) Originators component id
34、entity number Specification available from: SPECIFICATION ISSUE STATUS DATE ELECTRONIC COMPONENTS OF ASSESSED QUALITY MANUFACTURER(S) REFERENCE NUMBERS SEE NOTES 1 AND 2 BELOW a DETAIL SPECIFICATION IN ACCORDANCE WITH BS 9721:1985 SIGNAL TRANSFORMER BRIEF TECHNICAL DESCRIPTION For detail dimensions
35、and schematic diagram see sheet 8 NOTE 1It may be possible to procure this component from any manufacturer holding a current BS9720 Capability Approval Certificate (listed in PD9002) for such wound components defined herein, i.e.where this component falls within the manufacturer(s) approved limits.
36、NOTE 2Current Approved Manufacturers are: a Manufacturer Capability Approval No. Manufacturers Ref. No. BS 9721/XYZ/1234 a The listing of manufacturers in a copy of this document issued by a potential customer is at the customers discretion.BS9721:1985 4 BSI 01-2000 Blank detail specification Sheet
37、2 (of 8) Originators component identity number Signal transformer to BS9721:1985 ISSUE STATUS Ratings and characteristics (see3.3 of BS9721:1985) DATE Climatic category Maximum temperature range Mass Vibration (see BS2011-2.1Fc) Bump (see BS2011-2.1Eb) Shock (see BS2011-2.1Ea) Solderability (see BS2
38、011-2.1Ta) Robustness of terminations (see test Ua, Ub, Uc or Ud of BS2011-2.1U as appropriate) Rapid change of temperature (see BS2011-2.1Na) Frequency range and response Input signal level Impedances: Source Load Voltage transformation ratio Peak working voltage Direct current in windingsBS9721:19
39、85 BSI 01-2000 5 Blank detail specification Sheet 3 (of 8) Originators component identity number Signal transformer to BS9721:1985 ISSUE STATUS Inspection requirements (see notes) DATE TEST IL AQL BS 9720:1983 Reference Performance requirements and conditions of test DESIGN VERIFICATION ONLY: 2 spec
40、imens, no failures (see4.2 of BS9721:1985). Design verification inspection comprises those tests listed below plus all those selected for conformance inspection. Design verification tests shall only be performed when specifically invoked by the relevant order. Insulation resistance (hot) As required
41、 1.2.4.2.2 Temperature rise As required 1.2.4.22 Endurance (short term) As required 1.2.7.1 IN PROCESS INSPECTION: To be conducted during manufacture if a screen is specified Isolating screen 100% 1.2.4.8.2 1.2.2.2 Isolating screen position S4 1% 1.2.2.1 TESTS ON COMPLETED COMPONENTS Visual inspecti
42、on 100% 1.2.2 Dimensions 100% 1.2.3 Voltage transformation ratio 100% 1.2.4.16BS9721:1985 6 BSI 01-2000 Blank detail specification Sheet 4 (of 8) Originators component identity number Signal transformer to BS 9721:1985 ISSUE STATUS Inspection requirements (see notes) DATE TEST IL AQL BS 9720:1983 Re
43、ference Performance requirements and conditions of test TESTS ON COMPLETED COMPONENTS (continued) Voltage proof a 100% 1.2.4.4 Insulation resistance (Standard atmosphere) 100% 1.2.4.2.1 THE APPROPRIATE TEST(S) SHOULD BE SELECTED FROM THE FOLLOWING FIVE: Inductance and a.c.resistance 100% 1.2.4.7 Lea
44、kage inductance 100% 1.2.4.14 Insertion loss 100% 1.2.4.18.1 Return loss 100% 1.2.4.18.2 Frequency response 100% 1.2.4.19 a This test should be performed before insulation resistance.BS9721:1985 BSI 01-2000 7 Blank detail specification Sheet 5 (of 8) Originators component identity number Signal tran
45、sformer to BS 9721:1985 ISSUE STATUS Inspection requirements (see notes) DATE TEST IL AQL BS 9720:1983 Reference Performance requirements and conditions of test TESTS ON COMPLETED COMPONENTS (continued) Isolating screens (if a screen is specified) 100% A test is made to confirm the presence of isola
46、ting screens using the method for electrostatic screens (see1.2.4.8.1 of BS9720:1983) Q factor 100% 1.2.4.9 Phase test 100% 1.2.4.26 Acoustic noise 100% 1.2.4.25 D.C. winding resistance S4 1% 1.2.4.1.1 Continuity S4 1% 1.2.4.1.2 Electrostatic screens S4 1% 1.2.4.8.1 Self-capacitance S4 1% 1.2.4.15.1
47、BS9721:1985 8 BSI 01-2000 Blank detail specification Sheet 6 (of 8) Originators component identity number Signal transformer to BS 9721:1985 ISSUE STATUS Inspection requirements (see notes) DATE TEST IL AQL BS 9720:1983 Reference Performance requirements and conditions of test TESTS ON COMPLETED COM
48、PONENTS (continued) Interwinding capacitance S4 1% 1.2.4.15.2 Capacitance unbalance S4 1% 1.2.4.10 Impedance unbalance S4 1% 1.2.4.11 Voltage unbalance S4 1% 1.2.4.12 Resistance unbalance S4 1% 1.2.4.13 Induced high voltage S3 1.5% 1.2.4.5 Insulation resistance (hot) S3 1.5% 1.2.4.2.2 Inherent self-
49、resonance S3 1.5% 1.2.4.17.1BS9721:1985 BSI 01-2000 9 Blank detail specification Sheet 7 (of 8) Originators component identity number Signal transformer to BS 9721:1985 ISSUE STATUS Inspection requirements (see notes) DATE TEST IL See notes AQL BS 9720:1983 Reference Performance requirements and conditions of test TESTS ON COMPLETED COMPONENTS (continued) Resonant assemblies S3 1.5% 1.2.4.17.2 No-load current S1 4% 1.2.4.3.1 Total harmonic distortion S1 4% 1.2.4.21 Magnetic radiation S1 4% 1.2.4.24 Magnetic shielding S1 4% 1.2.4.6.1 Insert additiona
