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1、BRITISH STANDARD CONFIRMED JANUARY 1993 BS 90:1975 Specification for Direct-acting electrical recording instruments and their accessories UDC 621.317.7.087.6 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9
2、0:1975 This British Standard, having been approved by the Electrical Industry Standards Committee, was published under the authority of the Executive Board on 28 February 1975 BSI 01-2000 First published October 1919 First revision April 1927 Second revision May 1929 Third revision August 1940 Fourt
3、h revision February 1975 The following BSI references relate to the work on this standard: Committee reference ELE/13 Draft for comment 70/23154 ISBN 0 580 08279 2 Co-operating organizations The Electrical Industry Standards Committee under whose supervision this British Standard was prepared consis
4、ts of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical CommitteeDepartment of the Environment Association of Consulting Engineers*Department of Trade and Industry* Association of Manufacturers of DomesticElectric Cabl
5、e Makers Confederation Electrical AppliancesElectrical Contractors Association Association of Mining Electrical andElectrical Contractors Association of Scotland Mechanical EngineersElectrical Research Association Association of Supervisory and ExecutiveElectricity Supply Industry in England and Eng
6、ineers*Wales* British Electrical and Allied ManufacturersElectronic Engineering Association AssociationEngineering Equipment Users Association* British Electrotechnical Approvals Board forInstitution of Electrical Engineers* Household EquipmentInstitution of Electrical and Electronics British Non-Fe
7、rrous Metals FederationTechnician Engineers British Radio Equipment ManufacturersLighting Industry Federation Limited AssociationMinistry of Defence* British Railways BoardNational Inspection Council for Electrical British Steel CorporationInstallation Contracting Crown Agents for Oversea Government
8、s andOil Companies Materials Association AdministrationsPost Office* Department of EmploymentSouth of Scotland Electricity Board (HM Factory Inspectorate) The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with the following, wer
9、e directly represented on the committee entrusted with the preparation of this British Standard. British industrial Measuring and ControlScientific Instrument Manufacturers Apparatus Manufacturers AssociationAssociation National Physical Laboratory (Department ofDepartment of Trade and Industry Trad
10、e and Industry)(British Calibration Service) Electrical Power Engineers Association Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 90:1975 B
11、SI 01-2000i Contents Page Co-operating organizationsInside front cover Forewordiii 1Scope1 2Definitions2 3Classification10 4Permissible intrinsic errors and reference conditions related to the measured quantity11 5Permissible intrinsic errors and reference conditions related to time-keeping14 6Permi
12、ssible intrinsic errors and reference conditions for accessories15 7Permissible limits of variations16 8Permissible limits of variations for interchangeable accessories19 9Electrical and mechanical requirements of instruments and accessories19 10Constructional requirements for instruments and their
13、accessories27 11Markings and symbols for instruments and their accessories27 12Categories of test30 Appendix A Concepts36 Appendix B Friction effect of electrical measuring instruments of the direct acting, continuous line recording type40 Figure 1 Determination of maximum value of friction effect21
14、 Figure 2 Effective range 8 A to 50 A36 Figure 3 Effective range 80 V to 110 V36 Figure 4 Effect of temperature38 Figure 5 Effect of temperature38 Figure 6 Effect of frequency39 Figure 7 Analysis of friction effect41 Figure 8 Analysis of friction effect42 Table 1 Limits of intrinsic error of instrum
15、ents related to the measured quantity expressed as a percentage of the fiducial value11 Table 2 Preconditioning of instruments12 Table 3 Reference conditions for the influence quantities related to the measured quantity13 Table 4 Reference conditions for voltage, current and power factor related to
16、the measured quantity14 Table 5 Limits of intrinsic error related to the time keeping expressed as a percentage of the true elapsed time14 Table 6 Reference conditions for the influence quantities related to time-keeping15 Table 7 Limits of intrinsic error of an accessory as a percentage of the fidu
17、cial value15 Table 8 Normal values of the limits of the nominal range of use and allowable variation as a percentage of the measuring class index17 Table 9 Permissible limits of variation for a magnetic induction of 0.5 mT18 Table 10 Variation due to mounting on a ferromagnetic panel18 Table 11 Norm
18、al values of the limits of the nominal range of use related to time keeping19 Table 12 Relationship between the type of recording instrument, the type of chart driving mechanism and the accuracy class20 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:13:35 GM
19、T+00:00 2006, Uncontrolled Copy, (c) BSI BS 90:1975 ii BSI 01-2000 Page Table 13 Overload test of short duration23 Table 14 Current factor for overloads of short duration for shunts24 Table 15 Value of test voltage26 Table 16 Examples of markings related to the reference conditions and nominal range
20、s of use for instruments and accessories30 Table 17 Symbols for marking instruments and accessories31 Table 18 Lower limit of effective range36 Table 19 Examples of limits of effective range and fiducial values37 Publications referred toInside back cover Licensed Copy: London South Bank University,
21、London South Bank University, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 90:1975 BSI 01-2000iii Foreword This British Standard has been prepared under the authority of the Electrical Industry Standards Committee. Wherever possible it is based on IEC Publication 258 “Direct rec
22、ording electrical measuring instruments and their accessories”. Apart from changes in format, the chief differences between this revision and the previous one lies in the performance classification of recorders. In accordance with international practice the concept of class accuracy has been used th
23、roughout; the performance of recorders is characterized by a number, termed the class index, which designates the upper limit of instrument error, expressed in percent, when the instrument is used under reference conditions. Further, errors in recording are related, not to the maximum scale value as
24、 in the previous edition, but to a “fiducial value” which is clearly defined for each type of recorder. Under the class index system of classification the permitted changes of error with varying influence quantities ambient temperature, position, frequency, external magnetic field, etc. are implicit
25、 in the classification, and consequently it has not been necessary as in the past to include tables of the variations of error permitted for each influence quantity for each kind of recorder. A further change, which has been made in order to assist the user to decide whether a recorder is suitable f
26、or his purpose, is the introduction of a list of recommended symbols which are to be marked on the instrument. These symbols indicate not only the types of measuring element and chart-driving mechanism, but also the measuring class index, the time-keeping class index, the test voltage and other rele
27、vant information. The effect of pen-to-paper friction has, as previously, been excluded in determining the errors of recording, but this revision requires that the friction effect shall be determined, where applicable, in a specified manner, and useful information on the subject is given in an appen
28、dix. Instruments of the indirect acting type, in which the indicating or marking device is driven by a motor or other device controlled electromagnetically or electronically by the measured quantity, are covered by BS 5164 “Indirect-acting electrical indicating and recording instruments and their ac
29、cessories”. 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 documen
30、t comprises a front cover, an inside front cover, pages i to iv, pages 1 to 42, an inside back cover 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. Licensed Copy:
31、 London South Bank University, London South Bank University, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 90:1975 BSI 01-20001 1 Sco
32、pe 1.1 This British Standard specifies requirements for direct-acting electrical recording instruments, which are used for recording the instantaneous, effective or mean values of one or more measured quantities as a function of time. It refers to strip, drum and disc recording instruments, such as
33、ammeters; voltmeters; single-phase and polyphase wattmeters, varmeters and phasemeters; frequency recorders. It applies to those recording instruments which incorporate rectifiers or diodes and to thermocouple recording instruments, also to certain accessories used with such apparatus, such as shunt
34、s; series resistors and impedances. Other accessories may be associated with instruments provided that the instrument has been calibrated together with the accessory. 1.2 The standard also applies to electrically operated measuring equipments provided that the electrically operated recording measuri
35、ng instrument (receiver) only is considered, and that the relationship between the non-electrical and the electrical quantity is known. Additionally, it applies to recording instruments incorporating electronic devices in their auxiliary circuits. 1.3 The standard generally does not apply to recordi
36、ng instruments having electronic devices other than rectifiers or diodes in the measuring circuit. However, at the choice of the manufacturer, recording instruments together with their non-interchangeable accessories having electronic devices other than rectifiers and diodes in the measuring circuit
37、 shall be considered as included in the scope of the present standard provided that they are marked “BS 90” and marked with the class index and the appropriate symbol from Table 17. 1.3.1 Examples include recording instruments together with non-interchangeable accessories, if any, having neither an
38、incorporated supply source nor needing an external supply source. The electronic devices of these recording instruments are energized by the measured quantity and will, in some circumstances, be used for the protection of the recording instrument. 1.3.2 Examples also include recording instruments to
39、gether with non-interchangeable accessories, if any, having an incorporated supply source, in general a battery, provided that the electronic devices are used for affecting the recorded value only, and that the voltage of the source and any voltage generated from that source do not exceed the limit
40、of extra low voltage. 1.3.3 An external supply source is allowed when the nominal circuit voltage (circuit insulation voltage) of the measuring circuit does not exceed the limit of extra low voltage. 1.4 The standard does not apply to: recording instruments having a square-wave response greater than
41、 90 % of the effective range on a square wave with an amplitude equal to the effective range and a frequency of more than 5 Hz; multi-purpose recording instruments and ohmmeters; integrating recording instruments; indirect-acting recording instruments; recording instruments in which the measured qua
42、ntity is presented in the form of digits, codes, punched cards etc. recording instruments in which the chart movement is a function of a quantity other than time. 1.5 This standard does not contain requirements for protection against environmental conditions. NOTEThe titles of the British Standards
43、referred to in this standard are listed on the inside back cover. 1.6 This standard does not specify requirements concerning dimensions of instruments or detailed requirements concerning terminal markings and diagrams of connection. Licensed Copy: London South Bank University, London South Bank Univ
44、ersity, Fri Dec 08 01:13:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 90:1975 2 BSI 01-2000 2 Definitions For the purpose of this British Standard, the following definitions and those of BS 4727-1:Group 04 apply. 2.1 General terms 2.1.1 electrically operated measuring recording instrument (recei
45、ver) an electrically operated measuring instrument used as the recording means of an electrically operated measuring equipment 2.1.2 Accessory Circuit element (instrument transformer, resistor, impedance, etc.) which is associated with the measuring instrument either in a permanent or in a non-perma
46、nent manner. 2.1.2.1 interchangeable accessory an accessory having its own properties and accuracy, these being independent of those of the instrument with which it may be associated NOTEAn accessory is considered to be interchangeable when its rated characteristics are known and marked and are suff
47、icient to enable its errors and variations to be determined without using the associated instrument. For example, a shunt whose adjustment takes into account an instrument current which is not negligible and which is known is considered to be interchangeable. 2.1.2.2 accessory of limited interchange
48、ability an accessory adjusted to take into account the electrical characteristics of a type of instrument, e.g. when the instrument current is not negligible in comparison with a shunt current in these circumstances, the standard applies to any combination of instrument and accessory of the relevant
49、 types of a manufacturer unless he states otherwise. Each component of the combination has its own class index instruments intended to be used with these accessories are considered to have limited interchangeability 2.1.2.3 non-interchangeable accessory an accessory adjusted during manufacture to take into account the electrical characteristics of a specific instrument. The standard then applies to the particular combination of instrument and accessory and the accessory has no class index of its own 2.1.3 instrumen
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