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1、INTERNATIONAL STANDARD 2954 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION sMExflYHAPOflHAII OPTAHM3AWiR n0 C?AHAPTH3AIlM.OAGANISATlON INTERNATIONALE DE NORMALISATION Mechanical vibration of rotating and reciprocating machinery - Requirements for instruments for measuring vibration severity Vibratio
2、ns mkcaniques des machines townantes ou alternatives - Sp an indicator set which contains an amplifier, correcting filter networks for the frequency response and an indicating or recording instrument; and a power supply system. The requirements described in this clause apply to the general character
3、istics of the complete assembly of the pickup and the true v,., indicator set. Clauses 4 and 5 contain the detailed requirements for each of these main units. The instruments covered by this International Standard give direct indication or recording of root-mean-square vibration velocity, which is d
4、efined as the measuring unit of the vibration severity. 3.1 The frequency range of the vibration severity measuring instrument shall be from 10 to 1 000 Hz. NOTE - This means that the frequency range corresponds to the frequency interval employed in the evaluation scale in IS0 2372. NOTES 1 A method
5、 of checking true root-mean-square indication is described in an annex. 2 Subject to limitation of the measuring-frequency range, these instruments may be used for other applications where similar accuracy of measurement is required, for example measurement of vibration velocity of structures, tunne
6、ls, bridges, etc. 3.2 The sensitivity within the measuring-frequency range shall not deviate from the reference sensitivity at 80 Hz by more than the quantities given in the table. TABLE - Sensitivity relative to the reference sensitivity at 80 Hz and limiting values of the permissible deviation wit
7、hin the frequency interval from 1 to 10 000 Hz 2 DEFINITIONS The terms used in this International Standard are defined in the following IEC Publications and IS0 International Standards : IEC 184, Methods for specifying the characteristics of electromechanical transducers for shock and vibration meas
8、urements. IEC 222, Methods for specifying the characteristics of auxiliary equipment for shock and vibration measurement. IS0 204 1, Vibration and shock - Vocabulary. IS0 2372, Mechanical vibration of machines with operating speeds from 10 to 200 rev/s - Basis for specifying evaluation standards. IS
9、0 2373, Mechanical vibration of certain rotating electrical machinery with shaft heights between 80 and 400 mm - Measurement and evaluation of the vibration severity. Frequency HZ Relative sensitivity Nominal value Minimum value Maximum value 1 - - 0.01 2.5 0,016 0.01 0,025 10 1s 0.8 1.1 20 I.0 0.9
10、1,l 40 1.0 0.9 1,1 80 1,o 1.0 1 .o 160 13 0.9 1.1 500 1.0 0.9 1.1 1000 1 .o W3 1.1 4000 0,016 0.01 0.025 10000 - 0.01 To minimize measurement errors caused by the interference due to vibrations with frequencies outside the measuring-frequency range, the sensitivity shall decrease Copyright Internati
11、onal Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 02:04:19 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2954-1975 (E) rapidly in a clearly defined manner at the limit
12、s of the frequency range. Both the required nominal values of the sensitivity and the permissible minimum and maximum values are given in the table. To preclude doubts about the course of the sensitivity between the cutoff frequencies shown in the table, figure 1 illustrates the course of the nomina
13、l value of the relative sensitivity and the limit of the permissible deviation within the whole frequency range from 1 to 10 000 Hz. NOTE - In some ceses it may be necessary to limit further the measuring-frequency range at its upper or lower boundaries to avoid interfering vibrations which are irre
14、levant to the assessment of the vibration characteristics of a machine. For this purpose the instrument may be equipped with additional high-pass or low-pass filters. It is recommended that the cutoff frequencies and edge steepness of these filters be selected in accordance with IEC specifications.
15、When the measuring-frequency range is narrowed down by additional filters, the measured value should not be used for assessing the vibration severity in accordance with IS0 2372 and IS0 2373. To avoid errors, it is necessary to state the cutoff frequencies for the measuring-frequency range as well a
16、s the measured value, for example vrms (40 to 100 Hz) = 7,5 mm/s. 3.3 The selection of the measurement range shall be such that the indication of the lowest level of the vibration severity to be measured shall be equal to at least 30 % of the full-scale value. The minimum and maximum levels of the v
17、ibration severity range (for example in accordance with table 1 of IS0 2372) shall be stated, for example “Measuring instrument for vibration severity with measurement range 0,28 to 28 mm/s”. 3.4 The error of the vibration severity measuring instrument is composed of the permissible deviations for t
18、he frequency response in accordance with 3.2 and the error in the absolute value of the sensitivity at the reference frequency of 80 Hz (i.e. calibration error). The measurement error may be up to a maximum of f 10 % of the indicated value, including the calibration error, at 80 % of full-scale valu
19、e. These limits of error apply over the whole operating temperature range authorized for the vibration pickup and indicator set (see 4.8 and 5.4), for all types of attachments to the vibration pickup (see clause 41, for all lengths of connecting cable between the vibration pickup and the indicator p
20、rovided by the manufacturer (see 4.14) and a + 10 % fluctuation in the supply voltage. NOTE - Only one of the above parameters shall be checked at a time. 3.5 For calibration, the pickup shall be excited by a sinusoidal vibration with a vibration direction which deviates by not more than + 5O from t
21、hat of the sensitive axis of the pickup. The total harmonic distortion of the exciting vibration velocity shall not exceed 5 %. The velocity of the exciting vibration must be known with an uncertainty of less than f 3 % within the whole measuring- frequency range. It is recommended that the referenc
22、e value of the sensitivity at 80 Hz be adjusted to v, = 100 mm/s at a room temperature of 20 + 2 “C. 1.6 1,l IOU 8 6 t 2 4 5 3 t 1.6 .s G 10-l i 8 L/j i I I 100 l.G 2 2.5 3 4 5 6 8 10 1.6 2 2.5 3 4 5 6 8 10 1.6 2 2.5 3 4 5 6 8 lo3 1.6 2 2.5 3 4 5 6 8 lo4 Frequency, Hz -+ FIGURE 1 - Nominal value of
23、relative sensitivity and limits of permissible deviation 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 02:04:19 MDTNo reproduction or networking permitted without license fro
24、m IHS -,-,- IS0 2954-1975 (E) 4 REQUIREMENTS FOR THE VIBRATION PICKUP AND CONNECTING CABLE 4.1 The pickup shall be of the seismic type, i.e. it shall measure the vibrations of interest by comparison with a static reference system determined by the mode of operation of the pickup. 4.2 If a vibration
25、pickup designed for attachment to the object of measurement is used, this shall be affixed by a rigid mechanical connection, for example cementing, clamp- ing or screwing on or by means of a probe tip. No mechanical resonances of the rigid mechanical attachment or of the probe tip shall appear in th
26、e operating frequency band of the pickup. 4.3 For all types of attachment, the transverse sensitivity ratio shall be less than 0,l over the whole measuring-frequency range. The maximum level of vibration velocity for linear response of pickups shall be at least three times the vibration velocity at
27、full-scale deflection in the sensitive direction. 4.4 To show the extent to which the vibration pickup affects the object of measurement, the effective mass of the vibration pickup shall be indicated in an easily visible manner on the vibration measuring instrument. To suit a wide range of applicati
28、ons, the mass shall be kept to the minimum possible. NOTE - An indication of whether the mass of the pickup is too great can be obtained by the following method : Double the co-vibrating mass of the pickup by an additional mass; if the new indication shows a deviation from the original reading of mo
29、re than 12 %, the mass of the vibration pickup is too great as compared to the object of measurement and the result should be rejected. 4.5 The amplitude and frequency range of the vibration pickup shall be wide enough to avoid exceeding the permissible measurement error, as specified in 3.4. 4.6 Th
30、e pickup shall withstand, without changing its characteristics, vibration in all directions of at least three times its specified maximum vibration input. 4.7 The equivalent input quantity of the self-interference by hum and noise and the equivalent input quantity of the extraneous interference for
31、interference fields and excitations with a magnitude as stated below shall not affect the measurement by more than 10 %. When the value depends on the orientation of the instrument in the field, the most unfavourable value shall be used. The manufacturer shall state the results of tests made under t
32、he following disturbing conditions : 4.7.1 The pickup shall be subjected to a homogeneous magnetic field of 100 A/m and 50 or 60 Hz and the field intensity shall be measured before inserting the pickup. 4.7.2 The pickup shall be subjected to a homogeneous airborne noise field with an rms sound press
33、ure level of 100 dB re 2 X 10m5 Pa in each octave, produced by a random noise generator or a warble tone generator over the range 32 Hz to 2 kHz. 4.7.3 If the pickup has an electric conducting connection to the object of measurement and the indicator is line operated, an earth current of 100 mA rms
34、at the supply frequency shall be fed into the earth connection of the pickup and discharge at the earth terminal of the indicator set. 4.8 The operating temperature range of the vibration pickup and connecting cable within which the error of measurement will not exceed the limiting values specified
35、in 3.4 shall be stated. 4.9 The permissible temperature range to which the pickup and connecting cable can be subjected without damage shall be stated. 4.10 The maximum non-operational vibration and shock limits in any axis of the pickup to which it can be subjected without damage shall be stated. 4
36、.11 The maximum humidity to which the pickup and connecting cable (as well as supplementary cables which are included) can be exposed and continue to operate within specification shall be stated. If the pickup is to be used in any other hazardous environment such as corrosive atmosphere, the ability
37、 of the pickup to withstand this environment shall be indicated. If the pickup is to be used in an explosive atmosphere, its intrinsic safety shall be stated. 4.12 If applicable, the output of the pickup due to the base strain sensitivity at its mounting surface shall be indicated. 4.13 If available
38、, information on the predicted mean time between failures, life expectancy and the recommended time between recalibrations of the pickup shall be given. 4.14 If there is a connecting cable between the vibration pickup and the indicator set, its length shall be at least 1 m. The manufacturer shall st
39、ate what additional extension cables can be used without exceeding the tolerances in 4.7. 5 REQUIREMENTS FOR THE INDICATOR SET 5.1 The indicating instrument may be a pointer-type instrument, a g,raph recorder or a digital indicator. 5.1.1 The instrument shall indicate the true root-mean- square vibr
40、ation velocity. 5.1.2 The error in calibration of the instrument shall not exceed i 2,5 % of the full-scale value. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 02:04:19 MDTN
41、o reproduction or networking permitted without license from IHS -,-,- IS0 2954-1975 (E) 5.1.3 The indicator on the instrument shall be easily readable down to l/5 of the full-scale value. To identify the quantity measured and the unit, “v, in mm/s” shall be marked on the instrument. 5.2 When a sinus
42、oidal signal with a frequency anywhere within the measuring-frequency range and an amplitude permitting a steady-state nominal value of 70 % of the full-scale value is fed suddenly into the input of the indicator set at an equivalent voltage, the initial overshoot shall not be more than 10 % of the
43、final reading. There shall be no undershoot at the time when the difference of the peak values of the pointer oscillations, as compared to the final position of the pointer, is a maximum of I,5 % of the full-scale value. 5.3 For the purpose of checking the amplification, there shall be a device whic
44、h permits a setting of the total amplification of the indicator at a specific frequency (for example, 50 Hz) with an uncertainty of less than f 2 %. 5.4 The operating temperature range and non-operating temperature range of the indicator set shall be stated. 5.5 The maximum humidity to which the ind
45、icator set can be exposed and continue to operate within specification shall be stated. If the indicator set is to be used in any other hazardous environment such as a corrosive atmosphere, the ability of the indicator set to withstand this environment shall be stated. If the indicator set is to be
46、used in an explosive atmosphere, its intrinsic safety shall be stated. 6 POWER REQUIREMENTS The input power requirements for the pickup and indicator set shall be specified. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standa
47、rds 1/9972545001 Not for Resale, 04/27/2007 02:04:19 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2954-1975 (El ANNEX METHOD FOR TESTING rms-VOLTAGE INDICATORS A.1 TEST CIRCUIT u u=o ti r-l True rms meter A A Q a Square-wave generator a= L-4 T - -I, f Sine-wave gener
48、ator I Instrument under test W : network corresponding to the frequency response of the instrument under test FIGURE 2 - Circuit for the testing of rms-voltage indicators The following procedure is given as a method suitable for the testing of rms-voltage indicators. The values given below are based
49、 on the following definitions of crest factor : I? crest factor = = u . . . (1) where 0 is the larger amplitude of the generalized rectangular asymmetrical wave in figure 2 (i.e. G = lu,l or lu,l, whichever is larger); c is the root-mean-square value of the wave. 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Res