1、 Reference number ECMA-123:2009 Ecma International 2009 ECMA-275 3rd Edition / June 2015 Measurement of structure-borne vibration induced by small air moving devices COPYRIGHT PROTECTED DOCUMENT Ecma International 2015 Ecma International 2015 i Contents Page 1 Scope 1 2 Normative references 1 3 Term
2、s and definitions . 1 4 Descriptors . 2 5 Measurement uncertainty . 2 6 Design and performance requirements for test fixture . 3 6.1 Basic design 3 6.1.1 General . 3 6.1.2 Flow rate . 3 6.1.3 Static pressure . 4 6.1.4 Air/pressure distribution . 4 6.2 Damped panel 4 6.3 Mounting area 4 7 Installatio
3、n 4 7.1 Orientation of the AMD . 4 7.2 Mounting of the AMD 4 7.3 Mounting panel opening . 5 8 Operation of AMDs 5 8.1 Input power 5 8.1.1 Alternating current AMDs . 5 8.1.2 Direct current AMDs 5 8.2 Points of operation 5 9 Instrumentation . 6 9.1 Plenum pressure measurements . 6 9.2 Accelerometer an
4、d accelerometer system . 6 9.3 Signal conditioners . 6 9.4 Analyser 6 9.5 Basic calibration 7 10 Measurement procedure . 7 10.1 Preparation . 7 10.2 Operational test for AMD 7 10.3 Operational calibration . 7 10.4 Measurement . 8 10.4.1 Operational measurement and data averaging 8 10.4.2 Background
5、acceleration level measurement 9 10.5 Corrections for background acceleration levels 9 10.6 Accelerometer mounting 10 10.7 Accelerometer cable . 10 10.8 Accelerometer locations . 10 10.9 Data acquisition time 11 11 Test report 11 11.1 Information to be recorded . 11 11.2 Information to be reported 1
6、2 Annex A (informative) Suggested data format for presentation 13 Annex B (informative) Recommended voltages for testing AMDs that will operate with variable speeds . 19 ii Ecma International 2015 Annex C (informative) Sample specification of AMD structure-borne vibration levels 21 Annex D (informat
7、ive) Guidance on the development of information on measurement uncertainty 23 Ecma International 2015 iii Introduction This Standard contains the recommended methods for testing, determining, and reporting the vibration levels induced by small air moving devices (AMDs) that are found in cooling equi
8、pment used for information technology and telecommunications. The vibration levels are a function of operation speed and pressure loading. Previously, a variety of methods have been used by AMD manufacturers, information technology and telecommunications equipment manufacturers, consultants, and oth
9、ers to satisfy various needs. These diverse practices have, in many cases, made comparison of AMD vibration difficult. The practice recommended in this Standard provides a common basis for such comparisons that is consistent with current measurement standards. The use of this Standard is encouraged
10、to promote uniformity in the measurement and reporting of the vibration levels induced by AMDs for use in information technology and telecommunications equipment. The practice specified in this Standard is intended for use by AMD manufacturers, information technology and telecommunications equipment
11、 manufacturers, and testing laboratories. Results of measurements conducted in accordance with this practice are expected to be useful for engineering design, performance verification, comparisons among competing AMD designs, and evaluation of vibration isolation devices for small AMDs. This Standar
12、d may also be cited in purchase specifications and in contracts between suppliers and users. The basis for this Standard is from the Institute of Noise Control Engineering Recommended practice 1-96 5 - 16 The first edition of this Standard was issued in June 1998. This second edition corrected the a
13、ir flow rate equation, updates the reference for the measurement of the damped plate mobility and clarifies some wording. The third edition reflected the progresses of development of international counterpart standard, ISO 10302-2. The main updates are: - The format of the document is based on the l
14、atest Ecma template for standards. - The former, Clause 2 “Field of Application” was combined into new Clause 1 “Scope” (This change is based on both Ecma and ISO latest document structures.). Therefore, the remaining clause numbers were changed accordingly. - By referencing to ISO 10302-1, normativ
15、e references (new Clause 2) and the terms and definitions (new Clause 3) were well simplified. - For measurement uncertainty, new Annex D was introduced. . This Ecma Standard has been adopted by the General Assembly of June 2015. iv Ecma International 2015 “COPYRIGHT NOTICE 2015 Ecma International T
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22、THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.“ Ecma International 2015 1 Measurement of structure-borne vibration induced by small air moving devices 1 Scope This Standard covers vibration levels from s
23、mall air moving devices (AMDs) with mounting footprints of less than 0,48 m 0,90 m for the full-size test plenum defined in ISO 10302-1 and less than 0,18 m 0,3 m for the half size. It covers all types of AMDs which can be mounted on, and are self-supported at, the discharge or inlet plane of a test
24、 plenum box as specified in ISO 10302-1. Some guidance is given for non-self-supporting AMDs. The procedures defined in this Standard specify methods for determining the vibration levels that a small AMD would induce in an average structure used in information technology and telecommunications equip
25、ment. The methods specified in this Standard allow the determination of induced vibration levels for the individual AMD that is tested. These data may be used to determine the statistical values of vibration levels for a production series if levels are measured for several units of that series. 2 No
26、rmative references The following referenced documents are indispensable for the application of this Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 266, Acoustics Preferred f
27、requencies for measurements ISO 5348, Mechanical vibration and shock Mechanical mounting of accelerometers ISO 10302-1, Acoustics - Method for the measurement of airborne noise emitted and structure-borne-vibration induced by small air-moving devices Part 1: Airborne noise measurement ISO 16063-11,
28、Methods for the calibration of vibration and shock transducers Part 11: Primary vibration calibration by laser interferometry ISO 16063-21, Methods for the calibration of vibration and shock transducers Part 21: Vibration calibration by comparison with a reference transducer IEC 61260, Electroacoust
29、ics Octave-band and fractional-octave-band filters ISO/IEC Guide 98-3, Uncertainty in measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) 3 Terms and definitions For the purpose of this Standard, the terms and definitions given in ISO 10302-1 and the following apply.
30、 3.1 vibratory acceleration level, La ten times the logarithm to the base 10 of the ratio of square of the root-mean-square acceleration, a to the square of a reference value, a0 2 Ecma International 2015 202lg10 aaLa dB (1) where the reference value, a0, is 1 m/s2 NOTE 1 The width of the frequency
31、band shall be stated; for example, overall for all bands in the frequency range of interest, or one-third-octave band, etc NOTE 2 Other standards may use another reference value. NOTE 3 In this Standard, “vibratory acceleration level” is frequently referred to simply as “acceleration level”. 3.2 fre
32、quency range of interest one-third-octave bands with centre frequencies specified in ISO 266, from 25 Hz to 5 kHz inclusive 3.3 information technology and telecommunications equipment ITT equipment equipment for information processing, and components thereof, used in homes, offices, server installat
33、ions, telecommunications installations or similar environments ISO 7779:20103, 3.1.3 NOTE ECMA-275 is intended to support the designers of ITT equipment. 4 Descriptors The primary descriptor for vibration levels induced by an AMD is the energy average of the overall unweighted (non-frequency-weighte
34、d) vibratory acceleration level at the measurement locations for the frequency range of interest (see 3.2). This frequency range covers most of the frequency range covered by ISO 10302-1 for air-borne noise from AMDs, and adds the one-third-octave bands centred at 25 Hz to 80 Hz. The detailed descri
35、ptors are the unweighted one-third-octave band acceleration levels. Although the measurement apparatus and the procedures of this standard can also be used in conjunction with narrow band frequency analysis instrumentation to investigate specifics in more detail, such narrow band analysis is not spe
36、cified here. NOTE Acceleration measurements are convenient because non-intrusive lightweight accelerometers are readily available and simple to use. The overall unweighted acceleration level is chosen because it is a simple measure that correlates well with the A-weighted structure-borne noise level
37、 radiated by a structure (See References 7, 11). The A-weighted structure-borne noise level radiated from a vibrating structure is determined from the average acceleration level of the structure by a) converting from acceleration to velocity, b) correcting for the radiation efficiency of the structu
38、re and then, c) applying an A-weighting. To the first order, these three calculations cancel each other as a function of frequency except for a constant. This leaves the overall unweighted acceleration level as a simple measure of the fan-induced A-weighted structure-borne noise. 5 Measurement uncer
39、tainty The uncertainty of results obtained from measurements in accordance with this Standard should be evaluated, preferably in compliance with ISO/IEC Guide 98-3. If reported, the expanded uncertainty together with the corresponding coverage probability as defined in ISO/IEC Guide 98-3 shall be gi
40、ven. Guidance on the determination of the expanded uncertainty is given in Annex D. If, in a laboratory performing measurements in accordance with this Standard, current knowledge is still insufficient to fully apply ISO/IEC Guide 98-3, the values of the standard deviation of reproducibility, R0 giv
41、en Ecma International 2015 3 in Table 1, multiplied with a coverage factor of 2 to get an estimate of the expanded uncertainty for a coverage probability of 95 %, are recommended for provisional use in test reports. Table 1 Estimated values of the standard deviations of reproducibility of vibratory
42、acceleration levels of AMDs determined in accordance with ECMA-275 One-third-octave midband frequency Hz Standard deviation of reproducibility R0 dB Standard deviation of repeatability r0 dB 25 31,5 to 63 80 to 160 200 to 5000 5,0 5,0 3,0 2,0 2,0 1,0 1,0 1,0 Overall 25 to 5000 1,0 0,5 NOTE 1 These e
43、stimates are based on interlaboratory tests of five AMDs (three tubeaxial fans and two forward-curved blowers) in the capacity range of 0,001 6 to 0,137 m3/s conducted at two laboratories using three either half- or full sized plenums by five different operators following the guidelines of ISO 5725:
44、1986 NOTE 2 The standard deviations of reproducibility given above reflect the cumulative effects of all causes of measurement uncertainty, including variations from laboratory to laboratory, but excluding variations in the acceleration level from specimen to specimen. The standard deviation of repe
45、atability for the same specimen and the same laboratory measurement conditions is considerably smaller than the standard deviation of reproducibility. NOTE 3 The values given above apply to AMDs that are not damaged and are operating in a stable manner, under the test conditions defined in this Stan
46、dard. The estimated standard deviation of reproducibility in determining the overall unweighted acceleration level for the frequency range from 22,3 Hz to 5,7 kHz is less than 1 dB, and the standard deviation of reproducibility repeatability is less than 0,5 dB. 6 Design and performance requirements
47、 for test fixture 6.1 Basic design 6.1.1 General The basic design of the test plenum shall be as specified in ISO 10302-1 except the mounting panel assembly as specified in ISO 10302-1 shall be replaced by the damped plate specified in 6.2. 6.1.2 Flow rate The flow rate of the fan mounted on plenum
48、box under test conditions should be no greater than the value calculated in accordance with Equation (2): VVqq VV 00,max, (2) 4 Ecma International 2015 where max,Vq is the maximum volume flow rate of the scaled plenum in cubic metres per second; qV,0 is the maximum volume flow rate of full-size plen
49、um, in cubic metres per second, i.e. qV,0 = 1 m3/s; V0 is the nominal air volume of full-size plenum defined in ISO 10302-1, in cubic metres, i.e. V0 = 1,3 m3; V is the nominal air volume of any scaled plenum, in cubic metres 6.1.3 Static pressure The static pressure of the AMD operating on the plenum should be no greater than 750 Pa. 6.1.4 Air/pressure distribution All relative geometries (such as locations and proportions of the mounting panel or the exit port) shall be the same as those of the full-size plenum of ISO 1030
