1、BRITISH STANDARD CONFIRMED JANUARY1993 BS90:1975 Specification for Direct-acting electrical recording instruments and their accessories UDC 621.317.7.087.6BS90:1975 This BritishStandard, having been approved by the ElectricalIndustry StandardsCommittee, waspublished under the authorityof the Executi
2、veBoardon 28 February1975 BSI 01-2000 First published October1919 First revision April1927 Second revision May1929 Third revision August1940 Fourth revision February1975 The following BSI references relate to the work on this standard: Committee reference ELE/13 Draft for comment70/23154 ISBN 0 580
3、08279 2 Co-operating organizations The Electrical Industry Standards Committee under whose supervision this BritishStandard was prepared consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Departmen
4、t of the Environment Association of Consulting Engineers* Department of Trade and Industry* Association of Manufacturers of Domestic Electric Cable Makers Confederation Electrical Appliances Electrical Contractors Association Association of Mining Electrical and Electrical Contractors Association of
5、 Scotland Mechanical Engineers Electrical Research Association Association of Supervisory and Executive Electricity Supply Industry in England and Engineers* Wales* British Electrical and Allied Manufacturers Electronic Engineering Association Association Engineering Equipment Users Association* Bri
6、tish Electrotechnical Approvals Board for Institution of Electrical Engineers* Household Equipment Institution of Electrical and Electronics British Non-Ferrous Metals Federation Technician Engineers British Radio Equipment Manufacturers Lighting Industry Federation Limited Association Ministry of D
7、efence* British Railways Board National Inspection Council for Electrical British Steel Corporation Installation Contracting Crown Agents for Oversea Governments and Oil Companies Materials Association Administrations Post Office* Department of Employment South of Scotland Electricity Board (HM Fact
8、ory Inspectorate) The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard. British industrial Measuring and Control
9、Scientific Instrument Manufacturers Apparatus Manufacturers Association Association National Physical Laboratory(Department of Department of Trade and Industry Trade and Industry) (British Calibration Service) Electrical Power Engineers Association Amendments issued since publication Amd. No. Date o
10、f issue CommentsBS90:1975 BSI 01-2000 i Contents Page Co-operating organizations Inside front cover Foreword iii 1 Scope 1 2 Definitions 2 3 Classification 10 4 Permissible intrinsic errors and reference conditions related to the measured quantity 11 5 Permissible intrinsic errors and reference cond
11、itions related to time-keeping 14 6 Permissible intrinsic errors and reference conditions for accessories 15 7 Permissible limits of variations 16 8 Permissible limits of variations for interchangeable accessories 19 9 Electrical and mechanical requirements of instruments and accessories 19 10 Const
12、ructional requirements for instruments and their accessories 27 11 Markings and symbols for instruments and their accessories 27 12 Categories of test 30 Appendix A Concepts 36 Appendix B Friction effect of electrical measuring instruments of the directacting, continuous line recording type 40 Figur
13、e 1 Determination of maximum value of friction effect 21 Figure 2 Effective range8A to50A 36 Figure 3 Effective range80V to110V 36 Figure 4 Effect of temperature 38 Figure 5 Effect of temperature 38 Figure 6 Effect of frequency 39 Figure 7 Analysis of friction effect 41 Figure 8 Analysis of friction
14、 effect 42 Table 1 Limits of intrinsic error of instruments related to the measuredquantity expressed as a percentage of the fiducial value 11 Table 2 Preconditioning of instruments 12 Table 3 Reference conditions for the influence quantities related to themeasured quantity 13 Table 4 Reference cond
15、itions for voltage, current and power factor relatedtothe measured quantity 14 Table 5 Limits of intrinsic error related to the time keeping expressed asapercentage of the true elapsed time 14 Table 6 Reference conditions for the influence quantities related to time-keeping 15 Table 7 Limits of intr
16、insic error of an accessory as a percentage of thefiducialvalue 15 Table 8 Normal values of the limits of the nominal range of use and allowablevariation as a percentage of the measuring class index 17 Table 9 Permissible limits of variation for a magnetic induction of0.5mT 18 Table 10 Variation due
17、 to mounting on a ferromagnetic panel 18 Table 11 Normal values of the limits of the nominal range of use relatedtotime keeping 19 Table 12 Relationship between the type of recording instrument, thetypeofchart driving mechanism and the accuracy class 20BS90:1975 ii BSI 01-2000 Page Table 13 Overload
18、 test of short duration 23 Table 14 Current factor for overloads of short duration for shunts 24 Table 15 Value of test voltage 26 Table 16 Examples of markings related to the reference conditions andnominal ranges of use for instruments and accessories 30 Table 17 Symbols for marking instruments an
19、d accessories 31 Table 18 Lower limit of effective range 36 Table 19 Examples of limits of effective range and fiducial values 37 Publications referred to Inside back coverBS90:1975 BSI 01-2000 iii Foreword This BritishStandard has been prepared under the authority of the Electrical Industry Standar
20、ds Committee. Wherever possible it is based on IEC Publication258 “Direct recording 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 accordan
21、ce with international practice the concept of class accuracy has been used throughout; 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
22、. Further, errors in recording are related, not to the maximum scale value as 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 quantitiesambient
23、temperature, position, frequency, external magnetic field, etc.are implicit 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
24、made in order to assist the user to decide whether a recorder is suitable for 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
25、 class index, the time-keeping class index, the test voltage and other relevant 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 s
26、pecified manner, and useful information on the subject is given in an appendix. 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 BS5164 “In
27、direct-acting electrical indicating and recording instruments and their accessories”. 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 it
28、self confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesitoiv, pages1 to42, 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 indic
29、ated in the amendment table on the inside front cover.iv blankBS90:1975 BSI 01-2000 1 1 Scope 1.1 This BritishStandard specifies requirements for direct-acting electrical recording instruments, which are used for recording the instantaneous, effective or mean values of one or more measured quantitie
30、s as a function of time. It refers to strip, drum and disc recording instruments, such as 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
31、recording instruments, also to certain accessories used with such apparatus, such as shunts; 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 electrical
32、ly operated measuring equipments provided that the electrically operated recording measuring 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
33、devices in their auxiliary circuits. 1.3 The standard generally does not apply to recording 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 access
34、ories having electronic devices other than rectifiers and diodes in the measuring circuit shall be considered as included in the scope of the present standard provided that they are marked “BS90” and marked with the class index and the appropriate symbol from Table 17. 1.3.1 Examples include recordi
35、ng instruments together with non-interchangeable accessories, if any, having neither an 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 prot
36、ection of the recording instrument. 1.3.2 Examples also include recording instruments together 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 v
37、oltage of the source and any voltage generated from that source do not exceed the limit 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 stand
38、ard does not apply to: recording instruments having a square-wave response greater than90%of the effective range on a square wave with an amplitude equal to the effective range and a frequency of more than5Hz; multi-purpose recording instruments and ohmmeters; integrating recording instruments; indi
39、rect-acting recording instruments; recording instruments in which the measured quantity 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 pro
40、tection against environmental conditions. NOTEThe titles of the BritishStandards 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 o
41、f connection.BS90:1975 2 BSI 01-2000 2 Definitions For the purpose of this BritishStandard, the following definitions and those of BS4727-1:Group04 apply. 2.1 General terms 2.1.1 electrically operated measuring recording instrument(receiver) an electrically operated measuring instrument used as the
42、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-permanent manner. 2.1.2.1 interchangeable accessory an accessory havi
43、ng 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 sufficient to enable its errors and variations to be determined with
44、out 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 interchangeability an accessory adjusted to take into account the electrica
45、l 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 types of a manufacturer unless he states otherwise. Each compone
46、nt 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 inst
47、rument. 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 instrument with contacts an instrument in which the moving element operates contacts when it arrives at certain positions 2.1.4 instrument with magnetic s
48、creening an instrument shielded against the influence of external magnetic fields by ferromagnetic material 2.1.5 instrument with electrostatic screening an instrument provided with screens which are intended to protect it against the influence of external electric fields 2.1.6 self-contained instru
49、ment an instrument in which all accessory apparatus necessary to cause the indication to correspond with the value of the measured quantity is permanently connected and either enclosed in or permanently attached to the instrument case 2.1.7 multi-purpose instrument an instrument intended for the measurement of more than one kind of electrical quantity, e.g.a recording instrument measuring current and voltageBS90:1975 BSI 01-2000 3 2.1.8 distortion factor the ratio of the r.m.s. value of the harmonic content to the
