GB/T 10069.3-2024 Measurement of airborne noise emitted by rotating electrical machines and the noise limits - Part 3: Noise limits
1 Scope
This document:
——specifies test methods for the determination of sound power level of rotating electrical machines;
——specifies maximum A-weighted sound power levels for factory acceptance testing of network-supplied, rotating electrical machines in accordance with lEC 60034-1, having methods of cooling according to lEC 60034-6 and degrees of protection according to lEC 60034-5, and having the following characteristics:
• standard design, either AC or DC, without additional special electrical, mechanical, or acoustical modifications intended to reduce the sound power level;
• rated output from 1 kW (or kVA) up to and including 5500 kW (or kVA);
• rated speed not greater than 3750 r/min.
Excluded are noise limits for AC motors supplied by converters. For these conditions see Annex B for guidance.
The object of this document is to determine maximum A-weighted sound power levels, LWA in decibels, dB, for airborne noise emitted by rotating electrical machines of standard design, as a function of power, speed and load, and to specify the method of measurement and the test conditions appropriate for the determination of the sound power level of the machines to provide a standardized evaluation of machine noise up to the maximum specified sound power levels. This document does not provide correction for the existence of tonal characteristics.
Sound pressure levels at a distance from the machine may be required in some applications, such as hearing protection programs. Information is provided on such a procedure in Clause 7 based on a standardized test environment.
Note 1: This document recognizes the economic reason for the availability of standard noise-level machines for use in non-critical areas or for use with supplementary means of noise attenuation.
Note 2: Where sound power levels lower than those specified in Table 1, Table 2 or Table 3 are required, these are agreed between the manufacturer and the purchaser, as special electrical, mechanical, or acoustical design may involve additional measures.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3741 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Precision methods for reverberation test rooms
ISO 3743-1 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 1: Comparison method for a hard-walled test room
ISO 3743-2 Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms
ISO 3744 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane
ISO 3745 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Precision methods for anechoic rooms and hemi-anechoic rooms
ISO 3746 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Survey method using an enveloping measurement surface over a reflecting plane
ISO 3747 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering/survey methods for use in situ in a reverberant environment
ISO 4871 Acoustics - Declaration and verification of noise emission values of machinery and equipment
ISO 961 4-1 Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 1: Measurement at discrete points
ISO 9614-2 Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 2: Measurement by scanning
IEC 60034-5 Rotating electrical machines - Part 5: Degrees of protection provided by the integral design of rotating electrical machines (IP code) - Classification
IEC 60034-6 Rotating electrical machines - Part 6: Methods of cooling (IC Code)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
——IEC Electropedia: available at http://www.electropedia.org/
——ISO Online browsing platform: available at http://www.iso.org/obp
3.1
sound power level
LW
ten times the logarithm to the base 1 0 of the ratio of the sound power radiated by the source under test to the reference sound power [Wo = 1 pW (10-12 W)] expressed in decibels
3.2
sound pressure level
Lp
ten times the logarithm to the base 1 0 of the ratio of the square of the sound pressure to the square of the reference sound pressure [P o = 20 µPa (2 × 1 0 -5 Pa)] expressed in decibels
3.3
measurement surface index
LS
ten times the logarithm to the base 10 of the ratio of the measurement surface S to the reference surface [S0 = 1 m2] expressed in decibels
3.4
maximum value
value that defines the upper limit without further tolerance
4 Methods of measurement
4.1 Sound pressure level measurements and calculation of sound power level produced by the machine shall be made in accordance with ISO 3744, unless one of the alternative methods specified in 4.3 or 4.4 below applies.
Note: It is general practice to use the parallelepiped method for all shaft heights.
4.2 The maximum sound power levels specified in Table 1, Table 2 and Table 3 or adjusted by Table 4 relate to measurements made in accordance with 4.1.
4.3 When appropriate, one of the methods of precision or engineering grade accuracy, such as the methods of ISO 3741, ISO 3743-1, ISO 3743-2, ISO 3745, ISO 961 4-1 or ISO 961 4-2, may be used to determine sound power levels.
4.4 The simpler but less accurate method specified in ISO 3746 or ISO 3747 may be used, especially when the environmental conditions required by ISO 3744 cannot be satisfied (for example, for large machines).
However, to prove compliance with this document, unless a correction due to inaccuracy of the measurement has already been applied to the values determined by this method in accordance with ISO 3746 or ISO 3747, the levels of Table 1, Table 2 and Table 3 shall be decreased by 2 dB.
4.5 If testing under rated load conditions, the methods are preferred. However, other methods are allowed when the load machine and auxiliary equipment are acoustically isolated or located outside the test environment.
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Methods of measurement
5 Test conditions
6 Sound power level limits
7 Determination of sound pressure level
8 Declaration and verification of sound power values
Annex A (Informative) Typical values for measurement surface index
Annex B (Informative) Information on typical noise increments caused by converter supply
Bibliography
Figure B.1 Frequency spectrum of the currents at the output terminals of a 6‑pulse block-type current-source converter f1 = 50 Hz
Figure B.2 Frequency spectrum of the voltages at the terminals of a type A voltage-source converter (characterized by pronounced spikes close to the switching frequency and its multiples) f1 = 50 Hz, fs = 3 kHz
Figure B.3 Frequency spectrum of the voltages of a type B voltage-source converter (characterized by a broad voltage spectrum without pronounced spikes) f1 = 50 Hz, fs average = 4.5 kHz
Table 1 Maximum A-weighted sound power level, LWA in dB, at no-load (excluding motors according to Tables 2 and 3) (Method of cooling, IC code, see IEC 60034-6; Method of protection, IP code, see IEC 60034-5)
Table 2 Maximum A-weighted sound power level, LWA in dB, at no-load, 50 Hz, sinusoidal supply (for single speed three-phase cage induction motors)
Table 3 Maximum A-weighted sound power level, LWA in dB, at no-load, 60 Hz, sinusoidal supply (for single speed three-phase cage induction motors
Table 4 Expected increase, over no-load condition, in A-weighted sound power levels, ΔLWA in dB, for rated load condition (for motors according to Tables 2 and 3)
Table A.1 Typical values for measurement surface index for the conversion from sound power level to sound pressure level based on using parallelepiped measurement surface according to ISO 3744
Table B.1 Resonance frequencies of vibration mode r
Table B.2 Increments of A-weighted noise values
