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1、BRITISH STANDARD CONFIRMED AUGUST 1984 BS 2048-1: 1961 Incorporating amendments Nos. 1 and 2 Specification for Dimensions of fractional horse-power motors Part 1: Dimensions of motors for general use UDC 621.313.13.026.43 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006
2、, Uncontrolled Copy, (c) BSI BS 2048-1:1961 This British Standard, having been approved by the Electrical Industry Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council on 13 September 1961 BSI 12-1999 First p
3、ublished November 1953 First revision as BS 2048-1 September 1961 The following BSI references relate to the work on this standard: Committee references ELE/1, ELE/1/8 Draft for comment AA(ELE) 3593 ISBN 0 580 02047 9 Co-operating organizations The Electrical Industry Standards Committee, under whos
4、e supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty*Electricity Council, Generating Board and Air Ministry*the Area Boards in England and Wales* Associated Offices Technical Com
5、mitteeElectronic Engineering Association Association of Consulting EngineersEngineering Equipment Users Association* (Incorporated)*Independent Cable Makers Association Association of Supervising ElectricalInstitution of Electrical Engineers Engineers*Ministry of Aviation* British Electrical and All
6、ied IndustriesMinistry of Labour (Factory Inspectorate)* Research AssociationMinistry of Power British Electrical and Allied ManufacturersMinistry of Works Association*Municipal Passenger Transport Association, British Electrical Development AssociationIncorporated British Railways, The British Tran
7、sportNational Inspection Council for Electrical Commission*Installation Contracting Cable Makers AssociationNational Physical Laboratory (D.S.I.R.)* Crown Agents for Oversea Governments andOil Companies Materials Association* Administrations*Post Office* Electric Lamp Industry CouncilPublic Transpor
8、t Association (Incorporated) Electric Light Fittings AssociationSouth of Scotland Electricity Board Electrical Contractors AssociationWar Office* (Incorporated) Electrical Contractors Association of Scotland The Government departments and scientific and industrial organizations marked with an asteri
9、sk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this standard: British Gear Manufacturers AssociationHigh Commission of India British Oil Burner Manufacturers AssociationLloyds Register of Shipping British Pump Manufactu
10、rers AssociationLondon Transport Executive, The British British Refrigeration AssociationTransport Commission Engineer Surveyors AssociationMachine Tool Trades Association Federation of British Industries Amendments issued since publication Amd. No.DateComments 275July 1969 1074December 1972 Indicat
11、ed by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2048-1:1961 BSI 12-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1Scope1 2Frame designation1 3Letter symbols1 4Dimensions, tolera
12、nces and limits1 5Access for flange-fitting bolts2 6Keyways and flats2 7Electrical connections2 Figure 1 Dimensions for foot-mounted motors5 Figure 2 Dimensions for flange-mounted motors7 Table 1 Suffix letters1 Table 2 Letter symbols to indicate dimensions3 Table 3A Standardized dimensions for moto
13、rs with foot or resilient-base mounting4 Table 3B Approximate millimetre conversions for Table 3A4 Table 4A Standardized dimensions for motors with mounting flanges, with tapped or clearance fixing holes6 Table 4B Approximate millimetre conversions for Table 4A8 Licensed Copy: sheffieldun sheffieldu
14、n, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2048-1:1961 ii BSI 12-1999 Foreword This standard make reference to the following British Standards: BS 46, Keys and keyways and taper pins Part 1: Keys and keyways. BS 170, Electrical performance of fractional horse-power elec
15、tric motors and generators with class A insulation. BS 1083, Precision hexagon bolts, screws and nuts. BS 1802, Steel spring washers for general engineering and automobile purposes. BS 1916, Limits and fits for engineering Part 1: Limits and tolerances. This part of BS 2048, prepared under the autho
16、rity of the Electrical Industry Standards Committee, revises and supersedes the 1953 edition, and includes a wider range of frame sizes. The dimensions specified are those necessary to ensure that motors of different makes and of the same frame size complying with this specification, will be mechani
17、cally interchangeable, so far as shaft and mounting dimensions are concerned. For all practical purposes and for common frames, the shaft and mounting dimensions are interchangeable with those laid down in that part of the (American) NEMA Standard MG1 January 1959, dealing with general-purpose fract
18、ional horse-power motors. The exceptions are in the mounting dimensions for Frame 42 and in the dimensions for all flange-mounted motors. NOTEWhere metric equivalents are stated the figures in British units are to be regarded as the standard. The metric conversions are approximate. More accurate con
19、versions should be based on the tables in BS 350, “Conversion factors and tables”. 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 itsel
20、f confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendmen
21、t table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2048-1:1961 BSI 12-19991 1 Scope This specification applies to dimensions of fractional horse-power motors for general use with foot, flange or resilient-b
22、ase mounting (with or without belt-tensioning devices), with sleeve or ball bearings. The specification is applicable to the dimensions of single and polyphase a.c. motors and d.c. motors having enclosures in accordance with BS 170.1) NOTEMotors for particular applications will be specified in Part
23、2 of BS 2048 (in course of preparation). 2 Frame designation All frames shall be designated by the letter “B” followed by a number to indicate the centre height in 1/16 in (1.6 mm) units. For motors other than plain foot-mounted motors, the designation shall have an additional suffix letter in accor
24、dance with Table 1 (e.g. B56C). Rating plates of motors shall be marked with the appropriate frame designation. Table 1 Suffix letters 3 Letter symbols Letter symbols to indicate various dimensions are given in Table 2. Symbols relating to standardized dimensions are given in Column 1 of Table 2 and
25、 these dimensions are shown ringed in Figure 1 and Figure 2. Symbols relating to dimensions that are not standardized are given in Column 2 of Table 2. These dimensions are shown unringed in Figure 1 and Figure 2 and are included to facilitate and standardize the preparation and presentation of dime
26、nsional drawings. 4 Dimensions, tolerances and limits Dimensions shall be as laid down in Table 3A or Table 4A as appropriate. The dimensions are nominal except as indicated below and in the tables. a) Shaft centre height: dimension D: For resilient-base mounted motors fitted with belt-tensioning de
27、vices, dimension D is not standardized. b) Useful available length of shaft: for resilient-base mounted motors fitted with belt-tensioning devices, the value of dimension V may be reduced by a maximum of 1/8 in (3.2 mm). c) Flange spigot diameter: dimension AK: tolerance: plus 0.000 in to minus 0.00
28、3 in (0.08 mm). d) Flange spigot eccentricity: eccentricity with respect to the shaft not to exceed 0.004 in (0.10 mm) total indicator reading. e) Permissible run-out: axial run-out of flange face with respect to shaft axis not to exceed 0.004 in (0.10 mm) total indicator reading. 1) BS 170, “Electr
29、ical performance of fractional horse-power electric motors and generators with Class A insulation”. DescriptionSuffix letter Foot-mounted motor Motor with resilient mounting Motor with resilient-base mounting and belt-tensioning device Flange-mounted motor without feet, provided with tapped holes in
30、 the flange Flange-mounted motor without feet, provided with clearance holes in the flange Foot-mounted motor provided with a mounting flange having tapped holes Foot-mounted motor provided with a mounting flange having clearance holes A B C D E F NOTEThe relationship between frame size and output i
31、s not standardized because of the variety of types of supply (single and three-phase a.c., d.c., etc.) ratings and types of enclosures. tolerance for foot-mounted motorsplus 0 minus 1/16 in (1.6 mm) tolerance for resilient-base mounted motors, other than those fitted with belt-tensioning devicesplus
32、 0 minus 1/16 in (1.6 mm) Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2048-1:1961 2 BSI 12-1999 5 Access for flange-fitting bolts For motors with flanges and provided with clearance holes in the flanges, the profile of the casing betw
33、een the motor side of the flange and the motor itself shall be such that it is always possible to insert a hexagon-headed bolt, dimensioned according to BS 10832) and fitted with a spring washer dimensioned according to BS 18023), in the fixing holes to obtain a projection of the threaded portion, m
34、easured to the face of the flange, not less than dimension BZ. 6 Keyways and flats The shafts of motors with frames B56 and B66, shall have keyways for 3/16 in (5 mm) square keys 11/4 in (32 mm) long and 11/2 in (38 mm) long respectively. NOTEThe widths for these keyways, given in Table 3A and Table
35、 4A, are not in accordance with BS 46-14). Where motors are required for purposes that necessitate fitted keys, this should be specified by the purchaser when the tolerances in BS 46-1 should apply, otherwise the tolerances will be as given in Table 3 and Table 4. The shafts of motors with frames B3
36、6, B42 and B48, shall have flats with a useable length of not less than 70 per cent of dimension V. 7 Electrical connections The point at which the supply leads enter the motor shall be on the right-hand side of the machine when viewed from the non-driving end. 2) BS 1083, “Precision hexagon bolts,
37、screws and nuts”. 3) BS 1802, “Steel spring washers for general engineering and automobile purposes”. 4) BS 46, “Keys and keyways and taper pins”, Part 1, “Keys and keyways”. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2048-1:1961 BSI
38、 12-19993 Table 2 Letter symbols to indicate dimensions 123 Letter symbol Description of dimension Standardized dimensions Non-standardized dimensions AOverall width of feet or base at right angles to shaft AGDistance from machined face of flange to non-driving end of motor AHProjection of shaft fro
39、m machined face of flange AJPitch circle diameter of flange fixing holes AKFlange spigot diameter BOverall length of feet or base parallel with shaft BAFrom centre line of bolt holes or slots in the feet or base at driving end of motor to beginning of useful length of shaft BBDepth of spigot (minimu
40、m) BDOutside diameter of flange (maximum) BEThickness of flange BFSize of screw or bolt for which tapped or clearance holes are provided in flange BZMinimum projection of threaded screw or bolt from face of flange when a hexagon-headed screw or bolt with a spring washer fitted under the head, is ins
41、erted COverall length of motor including shaft extension DFrom centre line of shaft to bottom face of motor feet or base EECentres of bolt holes, or centres of slots in motor feet or base, at right angles to shaft axis FFCentres of bolt holes, or centres of slots in motor feet or base parallel with
42、shaft axis GThickness of motor feet HSize of fixing bolts for which clearance is provided in motor feet or base HTTravel of bolts in slots in motor feet or base JWidth of individual foot KLength of individual foot OTop of motor to bottom of feet or base O1Vertical distance from top of capacitor or o
43、ther auxiliary equipment to bottom of feet or base (where such equipment is mounted on the motor) O2Vertical distance from top of capacitor or other auxiliary equipment to bottom of motor (where such equipment is mounted on the motor) POverall diameter or width of casing, including cowl if fitted P1
44、Horizontal distance from side of capacitor, or other auxiliary equipment mounted on the right-hand side of the motor, to the opposite side of the motor, viewed from the driving end P2Horizontal distance from side of capacitor, or other auxiliary equipment mounted on the left-hand side of the motor,
45、to the opposite side of the motor, viewed from the driving end UDiameter of shaft extension UABottom of flat or keyway to opposite side of shaft VUseful length of shaft available for coupling, pinion, pulley etc. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:00:08 GMT+00:00 2006, Uncontr
46、olled Copy, (c) BSI BS 2048-1:1961 4 BSI 12-1999 Table 3A Standardized dimensions for motors with foot or resilient-base mounting Table 3B Approximate millimetre conversions for Table 3A (All dimensions are in inches) Framea size 1234 Fixing dimensions (Table 2 describes the symbols) Shaft dimension
47、sFlat or keyway dimensionsKey BADbEEFFH UcVb Nominal depth of flat Keywayd width UA Nominal size max.min.min.max.max.min. B36 B42 B48 B56 B66 15/16 21/16 21/2 23/4 31/8 21/4 25/8 3 31/2 41/8 31/4 31/2 41/4 47/8 57/8 2 25/16 23/4 3 5 3/16 1/4 5/16 5/16 3/8 0.3123 0.3748 0.4998 0.6248 0.7497 0.3119 0.
48、3744 0.4993 0.6243 0.7492 1 11/8 11/2 17/8 21/4 1/32 3/64 3/64 0.187 0.187 0.189 0.189 0.286 0.332 0.457 0.518 0.643 0.276 0.322 0.447 0.512 0.637 3/163/16 3/163/16 a NOTE Suffix letters, where used, have the meanings given in Table 1. b Not applicable to motors with resilient-base mounting fitted w
49、ith belt-tensioning devices see Sub-clauses 4 a) and 4 b). c The values given for dimension U represent the g6 limits specified in BS 1916, “Limits and fits for engineering”, Part 1, “Limits and tolerances”. Mating fitments for all general purposes, should have the H7 limits as specified in BS 1916. d See Note to first paragraph of Clause 6. Frame size 1234 Fixing dimensions (Table 2 describes the symbols) Shaft dimensionsFlat or keyway dimensionsKey BADEEFFH U V Nominal depth of flat Keyway width UA Nominal size m