1、BRITISH STANDARD BS3693:1992 Incorporating Amendment No. 1 Recommendations for Design of scales and indexes on analogue indicating instrumentsBS3693:1992 This British Standard, having been prepared under the directionof the Power EngineeringStandards Policy Committee, was published underthe authorit
2、y of the Standards Board and comes intoeffect on 31 January1992 BSI04-1999 BS3693-1 first published February1964 BS3693-2 first published November1969 First combined edition February1986 Second edition January1992 The following BSI references relate to the work on this standard: Committee reference
3、PEL/13 Draft announced in BSI News, November1991 ISBN 0 580 20252 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Power Engineering Standards Policy Committee (PEL/-) to Technical Committee PEL/13, upon which the following bodies were
4、represented: Department of Energy (Electricity Division) Department of Trade and Industry (National Measurement Accreditation Service) Department of Trade and Industry (National Physical Laboratory) Electricity Industry in United Kingdom GAMBICA (BEAMA Ltd.) General Electric Company Ltd. Institution
5、 of Electrical Engineers Institution of Incorporated Executive Engineers Amendments issued since publication Amd. No. Date Comments 7448 February 1993 Indicated by a sideline in the marginBS3693:1992 BSI 04-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Defini
6、tions 1 3 Factors influencing scale design 3 4 Determination of scale length and reading distance 4 5 Basic scales 5 6 Method of design of scales 5 7 Index 5 8 Proportions of scale marks 8 9 Parallax 8 10 Other considerations 9 11 Form of digits 11 Figure 1 Nomenclature for dials and scales 1 Figure
7、 2 Relations between reading distance and scale length with respect to resolution factor 6 Figure 3 Examples of recommended scale marks 7 Figure 4 Recommended shapes of pointer tip 9 Figure 5 Illustrations of types of scales 12 Figure 6 Effect of parallax 14 Figure 7 Measuring range8A to50A, the sub
8、divisions being omitted outside the measuring range 14 Figure 8 Measuring range80V to110V, the measuring range being between the dots 14 Figure 9 Measuring ranges0.06M7 to0.4M7 and0.1M7 to2M7, the scale mark bases of the measuring ranges being thickened 15 Table 1 Examples of scale lengths for readi
9、ng at distances of300mm and1000mm 5 Table 2 Direction of movement of the index for increasing magnitude of the measurand 10 Table 3 Dimensions of scale marks expressed as a ratio of scale length 10 Table 4 Examples of character heights for reading at distances of300mm, 600mm and1000mm 11 Publication
10、(s) referred to Inside back coverBS3693:1992 ii BSI 04-1999 Foreword This British Standard has been prepared under the direction of the Power Electrical Engineering Standards Policy Committee. It supersedes BS3693:1986, which is withdrawn. This edition introduces technical changes to bring the stand
11、ard up-to-date but it does not reflect a full review of the standard, which will be undertaken in due course. However, the Committee has agreed that geometric construction and form of digits should not be subject to standardization. Therefore BS3693A:1964 and BS3693B:1964 are now withdrawn. A Britis
12、h 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 document comprises a front
13、cover, an inside front cover, pagesi and ii, pages1to16, 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 theinside front cover.BS3693:1992 BSI 04-1999 1 1 Scope This
14、British Standard gives recommendations for the design of scales and indexes of analogue indicating instruments in which an index moves in relation to a fixed array of scale marks to display the value of a measured quantity, or in which the scale moves in relation to a fixed index. Basic designs are
15、given for scales for single, dual and multi-range fixed or portable instruments. This British Standard is applicable to scales with: a) black or dark coloured scale marks on a white or light coloured background; b) white or light coloured scale marks on black or dark dials; c) transilluminated scale
16、s. BS3693 can be applied in the design of both linear and non-linear scales. No recommendations are given for the design of scales displayed on cathode ray tubes. This British Standard can apply to non-electrical instruments. NOTEThe title of the publication referred to in this standard is given on
17、the inside back cover. 2 Definitions For the purposes of this British Standard the following definitions apply. NOTEFigure 1 illustrates some of the defined terms. 2.1 scale the ordered set of scale marks, together with any associated numbering, forming part of an indicating device 2.2 index the fix
18、ed or movable part of an indicating device whose position with reference to scale marks enables an indicated value to be determined NOTEExamples of an index include the following: a) pointer; b) luminous spot; c) liquid surface; d) recording pen. 2.3 dial that part of an indicating device, fixed or
19、moving, which carries the scale or scales Figure 1 Nomenclature for dials and scalesBS3693:1992 2 BSI 04-1999 2.4 graduation the process of setting out a scale NOTEThe use of the word “graduation” in the sense of a “graduation mark” is deprecated, the term “scale mark” being the defined term. 2.5 sc
20、ale mark a line or other mark on an indicating device corresponding to one or more defined values of a measurand 2.6 major scale mark a scale mark which is a primary divider of the scale. Major scale marks are emphasized generally by elongation relative to the minor marks, or by thickening all or pa
21、rt of the mark 2.7 minor scale mark a scale mark which is a secondary divider of the scale. Minor scale marks divide the distance between major scale marks into scale divisions (see2.13) 2.8 intermediate scale mark a minor scale mark which is emphasized in order to assist reading the scale between a
22、 pair of adjacent major scale marks 2.9 scale mark base the actual or implied line, part circle or straight, between the extreme end scale marks, from which one end of all the scale marks emanate 2.10 index path the line of travel, relative to the scale, of that place on the index, or on the geometr
23、ic prolongation of the index, which is effective in indicating the value of the measurand NOTEIn some instruments, the place on the index which is thus effective may vary with the position of the index. 2.11 boundary line a line, perpendicular to the scale marks, bounding the scale. The boundary lin
24、e may be coincident with the scale mark base or it may be arranged on the opposite side of the scale 2.12 scale length the length of the line (curved or straight) which passes through the centres of all the shortest scale marks contained between the first and the last scale marks NOTEThe scale lengt
25、h is expressed in units of length. 2.13 scale division the part of a scale between any two successive scale marks 2.14 length of a scale division the distance between any two successive scale marks, measured along the scale mark base NOTEThe length of a scale division is expressed in units of length
26、. 2.15 major scale division the part of a scale between any two successive major scale marks 2.16 intermediate scale division the part of a scale between any two successive intermediate scale marks or between an intermediate scale mark and an adjacent major scale mark 2.17 minor scale division the p
27、art of a scale between any two successive scale marks, one of which is a minor scale mark 2.18 scale range for a given scale, the set of values between the extreme scale marks NOTEThe scale range is expressed in the units marked on the scale, regardless of the units of the measurand. It is normally
28、stated in terms of its lower and upper limits, e.g.100C to200C. 2.19 measuring range the range defined by two values of the measurand within which the limits of error of a measuring instrument are specified 2.20 minimum scale value the smallest value of the measurand displayed by the scale 2.21 maxi
29、mum scale value the greatest value of the measurand displayed by the scaleBS3693:1992 BSI 04-1999 3 2.22 scale interval the difference between the scale values corresponding to two consecutive scale marks NOTEScale interval is expressed in the units marked on the scale, regardless of the units of th
30、e measurand. 2.23 linear scale a scale in which the divisions between successive scale marks denoting similar increments of the measurand are intended to have the same length 2.24 non-linear scale a scale in which the length of a scale division is not constant throughout the scale NOTEExamples of a
31、non-linear scale include the following: a) logarithmic scale; b) square-law scale. 2.25 multiple scale (multi-scale) a dial having more than one series of scale marks, etc.with different scale mark bases and a common index 2.26 dual scale two scales associated with a common index and a common scale
32、mark base, the scale marks being drawn in opposite directions on the scale mark base 2.27 multiple zone scale a scale in which the value of the scale interval varies in steps from one region to another 2.28 superimposed scale a scale provided throughout its effective length with two resolutions, one
33、 intended for close reading and fine resolution, the other being of coarser resolution and intended for reading at a distance or at a glance 2.29 interpolation the process of dividing a scale division by eye without the aid of scale marks 2.30 interpolated division one of the parts into which a mino
34、r scale division is divided by eye 2.31 scale factor the number, often one, by which the indication is multiplied to obtain the value of the measurand 2.32 accuracy the quality which characterizes the closeness of the indicated value of the measurand to the true value (conventional true value) 2.33
35、observation error the error made by the observer when reading the indication of an instrument NOTEThe term “reading error” is deprecated. 2.34 parallax when applied to a scale and index, the effect of the apparent change in the position of the index, relative to the scale marks, when the observer vi
36、ews the scale and index perpendicularly and obliquely 2.35 resolution the smallest change in the value of the measurand which can be meaningfully determined 2.36 interpolated resolution the smallest change in the value of the measurand to which a numerical value can be assigned by interpolation, i.e
37、.by estimating the distance between the index and the nearest scale mark NOTE 1For the purposes of this standard, the interpolated resolution is expressed as a percentage of the scale range. NOTE 2Unless otherwise stated, interpolation to fifths of a scale division is assumed. 2.37 resolution factor
38、 a number, designated r, having the same numerical value as the interpolated resolution expressed as a percentage, e.g.interpolated resolution0.5%: r = 0.5 2.38 moving element the moving part of an instrument, the deflection of which is observed 3 Factors influencing scale design 3.1 General 3.1.1 I
39、nterpolation to the required interpolated resolution It should be possible for a practised observer to interpolate a scale division to the required interpolated resolution. This resolution should be related to the accuracy class of the instrument of which the scale and index form part. The resolutio
40、n factor should be equal to or less than the class index of the instrument.BS3693:1992 4 BSI 04-1999 The statistical basis adopted for this standard is that, in at least95 observations out of every100 taken by practised observers positioned directly in front of the scale, an observation should not d
41、epart from the indicated value by more than the interpolated resolution of the scale when the illuminance (intensity of illumination) of the dial has a minimum value of130lx. 3.1.2 Speed of observation Where quickness of observation is a factor to be considered, interpolation to the required resolut
42、ion is important. For general applications, as the speed of observation becomes more important, so the required resolution factor increases, and vice versa. For instance, it is important that an automobile speedometer which would normally have a resolution factor of the order of1 be read quickly wit
43、hout a gross observation error, while quickness of observation is of much less importance when reading laboratory test instruments. 3.2 Interpolation 3.2.1 Research into human performance has shown that the fundamental principles in scale design given in3.2.2 to3.2.7 govern observation error resulti
44、ng from interpolation. 3.2.2 The proportion of observation errors depends upon the angle subtended at the observers eye by the interpolated division. Best performance is achieved when this angle is7 10 4rad. This is equivalent to an angle of2.59 of arc, or a width of0.2mm at a reading distance of300
45、mm. When the angle is larger then this, the number of observation errors increases and when the angle is less than 2.59 of arc the observation errors increase rapidly. 3.2.3 Where quickness of observation plays no important part in the reading process there may be some additional advantage in the re
46、duction of observation errors by choosing the minor division such that interpolating into halves achieves the required resolution factor. In practice this advantage has significance only with finely divided scales. 3.2.4 The method of scale division is important. For best performance it is recommend
47、ed that scale divisions related to1, 2 or5 units of the measurand should be used. This reduces mental calculation and thus minimizes observation errors. 3.2.5 There should not be more than four successive minor marks between any two other marks. Also, there should be not more than four intermediate
48、marks between two successive major marks. 3.2.6 There should be not more than four unfigured major marks between figured major marks. 3.2.7 There should not be two unfigured marks between adjacent figured marks. 4 Determination of scale length and reading distance 4.1 Basis for setting out scales Th
49、e basis for setting out all scales should be the scale length, and this basis applies equally whether the scale is full circle, part circle or straight. The dimensions of the scale should be related to the intended distance at which the scale is to be read with the minimum number of observation errors. 4.2 Minimum acceptable scale length The minimum acceptable scale length should be determined in accordance with the following. From3.2.2 it may be determined that: where: By definition, where: Therefore, Equation(3) results in the minimum acceptable
