Acoustics - Measurement of airborne noise emitted by rotating electrical machinery Engineering method for free-field conditions over a reflective plane
Standards Australia
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<text>AS 1081.1-1990 ACOUSTICS - MEASUREMENT OF AIRBORNE NOISE EMITTED BY ROTATING ELECTRICAL MACHINERY - ENGINEERING METHOD FOR FR</text>
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<text>PREFACE</text>
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<text>CONTENTS</text>
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<text>0 Introduction</text>
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<text>1 Scope and field of application</text>
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<text>1.1 General</text>
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<text>1.2 Measurement uncertainty</text>
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<text>2 References</text>
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<text>3 Definitions</text>
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<text>3.1 free field:</text>
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<text>3.2 free field over a reflecting plane:</text>
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<text>3.3 anechoic room:</text>
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<text>3.4 semi-anechoic room:</text>
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<text>3.5 sound pressure level</text>
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<text>3.6 surface sound pressure:</text>
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<text>3.7 surface sound pressure level</text>
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<text>3.8 sound power level</text>
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<text>3.9 frequency range of interest:</text>
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<text>3.10 measurement surface:</text>
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<text>3.11 reference box:</text>
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<text>3.12 measurement distance:</text>
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<text>3.13 background noise:</text>
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<text>4 Acoustic environment</text>
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<text>4.1 General</text>
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<text>4.2 Criteria for adequacy of the test environment</text>
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<text>4.3 Criterion for background noise</text>
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<text>4.4 Wind</text>
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<text>5 Instrumentation</text>
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<text>5.1 General</text>
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<text>5.2 The microphone and its associated cable</text>
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<text>5.3 Frequency response of the instrumentation system</text>
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<text>5.4 Weighting network and frequency analyser</text>
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<text>5.5 Calibration</text>
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<text>6 Installation and operation of the machine</text>
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<text>6.1 Machine mounting</text>
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<text>6.1.1 Resilient mounting</text>
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<text>6.1.2 Rigid mounting</text>
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<text>6.2 Operation of machine during test</text>
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<text>6.3 Auxiliary equipment and coupled machines</text>
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<text>7 Sound pressure levels on the measurement surface</text>
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<text>7.1 Reference box and measurement surfaces</text>
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<text>7.2 Microphone array</text>
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<text>7.2.1 Complete measurement position array</text>
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<text>7.2.2 Simplified measurement position array</text>
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<text>7.3 Conditions of measurement</text>
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<text>7.3.1 General</text>
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<text>7.3.2 Measurements with a sound level meter</text>
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<text>7.3.3 Measurements with RC- smoothing or integration systems</text>
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<text>8 Calculation of surface sound pressure level and sound power level</text>
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<text>8.1 Corrections for background noise</text>
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<text>8.2 Calculation of sound pressure level averaged over the measurement surface</text>
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<text>8.3 Calculation of surface sound pressure level</text>
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<text>8.4 Calculation of sound power level</text>
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<text>9 Information to be recorded</text>
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<text>9.1 Machine under test</text>
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<text>9.2 Acoustic environment</text>
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<text>9.3 Instrumentation</text>
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<text>9.4 Acoustical data</text>
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<text>10 Information to be reported</text>
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<text>Annex A - Qualification Procedures for the acoustic environment</text>
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<text>A.1 General</text>
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<text>A.2 Environmental conditions</text>
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<text>A.2.1 Properties of reflecting plane</text>
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<text>A.2.2 Reflecting objects</text>
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<text>A.2.3 Precautions for outdoor measurements</text>
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<text>A.3 Absolute comparison test to determine</text>
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<text>A.3.1 Procedure</text>
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<text>A.3.2 Locations of reference sound source in test environment</text>
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<text>A.3.3 Qualification requirements</text>
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<text>A.4 Reverberation test to determine K</text>
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<text>A.4.1 Test procedure</text>
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<text>A.4.2 Qualification requirements</text>
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<text>Annex B - Procedures for calculating A-weighted sound power level from octave or one-third octave band power levels</text>
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<text>Annex C - Method for estimating the difference in noise level between no-load and on-load operations</text>
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<text>C.1 General</text>
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<text>C.2 Installation and operation of machines</text>
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<text>C.2.1 Machine mounting</text>
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<text>C.2.2 Operation of machine during test</text>
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<text>C.3 Measurement array</text>
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<text>C.4 Measurement of sound pressure levels</text>
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<text>C.5 Estimation of differences in level of the noise between no-load and on-load operations</text>
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<text>C.6 Information to be recorded</text>
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<text>C.7 Information to be reported</text>
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Specifies an engineering method for measuring the sound pressure levels on a rectangular parallel piped surface enveloping the machine and for calculating sound power level produced by the machine. Applies to the rotating electrical machines, such as motors, and generators (d.c. and a.c.) without any limitations on the output voltage but with the limit of the linear dimensions not to exceed 15 m. Identical with and reproduced from ISO 1680-1.
This part of ISO 1680 specifies, in accordance with ISO 2204, an engineering method (grade 2) for measuring the sound pressure levels on a rectangular parallelepiped surface enveloping the machine and for calculating the sound power level produced by the machine. It outlines the procedures which may be used to evaluate the test environment and specifies the characteristics of suitable measuring instruments. A method is given for determining the A-weighted sound power level and, if required, octave or one-third octave band sound power levels of the machine from the mean of the sound pressure levels measured on the rectangular parallelepiped surface.
This part of ISO 1680 applies to the measurement of airborne noise from rotating electrical machines, such as motors and generators (d.c. and a.c. machines) without any limitation on the output or voltage, when fitted with their normal auxiliaries. It applies to rotating electrical machines with any linear dimension (length, width or height) not exceeding 15 m.
This part of ISO 1680 applies to measurements carried out in environmental conditions that meet the criteria given in clause 4 and annex A (environmental correction K 2 dB, correction for background noise 1 dB). If these criteria are not met, standard deviations of the test results may be greater than those given in table 1, i.e. the engineering grade of accuracy may not be achieved. The method given in ISO 1680/2 shall then be used, which will result in A-weighted sound power levels of lower accuracy. In this case, no reference shall be made to this part of ISO 1680.
| Document Type | Standard |
| Status | Current |
| Publisher | Standards Australia |
| Committee | AV-006 |
| Supersedes |
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