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1、 AS/NZS 60076.10:2009 Australian/New Zealand Standard Power transformers Part 10: Determination of sound levels (IEC 60076-10, Ed.1 (2001) MOD) AS/NZS 60076.10:2009 AS/NZS 60076.10:2009 This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee EL-008, Power Transformers. I
2、t was approved on behalf of the Council of Standards Australia on 16 March 2009 and on behalf of the Council of Standards New Zealand on 20 March 2009. This Standard was published on 15 April 2009. The following are represented on Committee EL-008: Australian Chamber of Commerce and Industry Austral
3、ian Industry Group Australian Institute of Petroleum Department of Environment, Water, Heritage and the Arts Electricity Engineers Association, New Zealand Energy Efficiency the intensity method reduces the influence of external sound sources, as long as their sound level is approximately constant.
4、The sound pressure method takes the above factors into account by correcting for background noise and reflections. For a detailed discussion of these measuring techniques, see IEC 60076-10-1: Determination of sound levels Application guide. vi NOTES The Standard is downloaded from Standard Sharing
5、COPYRIGHT 1 STANDARDS AUSTRALIA Australian/New Zealand Standard Power transformers Part 10: Determination of sound levels (IEC 60076-10, Ed.1 (2001) MOD) Any table, figure or text of the international standard that is struck through is not part of this standard. Any Australian/New Zealand table, fig
6、ure or text that is added is part of this standard and is identified by shading. 1 Scope This part of IEC 60076 defines sound pressure and sound intensity measurement methods by which sound power levels of transformers, reactors and their associated cooling auxiliaries may be determined. NOTE For th
7、e purpose of this standard, the term “transformer“ means “transformer or reactor“. The methods are applicable to transformers and reactors covered by the IEC 60076 series, IEC 60289, IEC 60076-11 and the IEC 61378 series, without limitation as regards size or voltage and when fitted with their norma
8、l cooling auxiliaries. This standard is primarily intended to apply to measurements made at the factory. Conditions on-site may be very different because of the proximity of objects, including other trans- formers. Nevertheless, the same general rules as are given in this standard may be followed wh
9、en on-site measurements are made. Annex ZA contains the specified sound levels for transformers for use in Australia and New Zealand. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies
10、. For undated references, the latest edition of the referenced document (including any amendments) applies. References to international standards that are struck through in this clause are replaced by references to Australian or Australian/New Zealand Standards that are listed immediately thereafter
11、 and identified by shading. Any Australian or Australian/New Zealand Standard that is identical to the International Standard it replaces is identified as such. IEC 60076 (all parts), Power transformers IEC 60076-1:1993, Power transformers Part 1: General AS 60076.1, Power transformers, Part 1: Gene
12、ral IEC 60076-11, Power transformers Part 11: Dry-type transformers AS 60076.11, Power transformers, Part 11: Dry-type transformers IEC 60289:1988, Reactors AS 1028, Power reactors and earthing transformers (identical to IEC 60289:1988) IEC 61043:1993, Electroacoustics Instruments for the measuremen
13、t of sound intensity Measurement with pairs of pressure sensing microphones COPYRIGHT 2 AS 4241, AcousticsInstruments for the measurement of sound intensityMeasurement with pairs of pressure sensing microphones (identical to IEC 61043:1993) IEC 61378 (all parts), Convertor transformers IEC 61672-1,
14、Electroacoustics Sound level meters Part 1: Specifications AS IEC 61672-1, ElectroacousticsSound level meters, Part 1: Specifications (identical to IEC 61672-1:2002) IEC 61672-2, Electroacoustics Sound level meters Part 2: Pattern evaluation tests AS IEC 61672-2, ElectroacousticsSound level meters,
15、Part 2: Pattern evaluation tests (identical to IEC 61672-2:2003) ISO 3746:1995, Acoustics Determination of sound power levels of noise sources using sound pressure Survey method using an enveloping measurement surface over a reflecting plane ISO 9614-1:1993, Acoustics Determination of sound power le
16、vels of noise sources using sound intensity Part 1: Measurement at discrete points 3 Terms and definitions For the purpose of this document, the definitions in IEC 60076-1, as well as the following definitions, apply. 3.1 sound pressure p fluctuating pressure superimposed on the static pressure by t
17、he presence of sound. It is expressed in pascals 3.2 sound pressure level Lp ten times the logarithm to the base 10 of the ratio of the square of the sound pressure to the square of the reference sound pressure (p0 = 20 106 Pa). It is measured in decibels 2 0 2 p lg01 p p L= (1) 3.3 sound intensity
18、I vector quantity describing the amount and direction of the net flow of sound energy at a given position. The unit is Wm2 3.4 normal sound intensity In component of the sound intensity in the direction normal to a measurement surface The Standard is downloaded from Standard Sharing COPYRIGHT 3 3.5
19、 normal sound intensity level LI ten times the logarithm to the base 10 of the ratio of the normal sound intensity to the reference sound intensity (I0 = 1 1012 Wm2). It is expressed in decibels 0 n I lg10 I I L= (2) NOTE When In is negative, the level is expressed as XX dB. 3.6 sound power W rate a
20、t which airborne sound energy is radiated by a source. It is expressed in watts 3.7 sound power level LW ten times the logarithm to the base 10 of the ratio of a given sound power to the reference sound power (W0 = 1 1012 W). It is expressed in decibels 0 W lg10 W W L= (3) 3.8 principal radiating su
21、rface hypothetical surface surrounding the test object which is assumed to be the surface from which sound is radiated 3.9 prescribed contour horizontal line on which the measuring positions are located, spaced at a definite horizontal distance (the “measurement distance“) from the principal radiati
22、ng surface 3.10 measurement distance X horizontal distance between the principal radiating surface and the “measurement surface“ 3.11 measurement surface hypothetical surface enveloping the source and on which the measurement points are located 3.12 background noise A-weighted sound pressure level w
23、ith the test object inoperative 4 Instrumentation and calibration Sound pressure measurements shall be made using a type 1 sound level meter complying with IEC 61672-1 and IEC 61672-2 and calibrated in accordance with 5.2 of ISO 3746. Sound intensity measurements shall be made using a class 1 sound
24、intensity instrument complying with IEC 61043 and calibrated in accordance with 6.2 of ISO 9614-1. The frequency range of the measuring equipment shall be adapted to the frequency spectrum of the test object, that is, an appropriate microphone spacer system shall be chosen in order to minimize syste
25、matic errors. COPYRIGHT 4 The measuring equipment shall be calibrated immediately before and after the measurement sequence. If the calibration changes by more than 0,3 dB, the measurements shall be declared invalid and the test repeated. 5 Choice of test method Either sound pressure or sound intens
26、ity measurements may be used to determine the value of the sound power level. Both methods are valid and either can be used, as agreed between manufacturer and purchaser at the time of placing the order. The sound pressure method of measurement described in this standard is in accordance with ISO 37
27、46. Measurements made in conformity with this standard tend to result in standard deviations of reproducibility between determinations made in different laboratories which are less than or equal to 3 dB. The sound intensity method of measurement described in this standard is in accordance with ISO 9
28、614-1. Measurements made in conformity with this standard tend to result in standard deviations of reproducibility between determinations made in different laboratories which are less than or equal to 3 dB. 6 Load conditions 6.1 General Load condition(s) shall be agreed between the manufacturer and
29、purchaser at the time of placing the order. If a transformer has a very low no-load sound level, the sound due to load current can influence the total sound level in service. The method to be used for summing the no-load and load current sound levels is given in Clause 14. Current taken by a reactor
30、 is dependent on the voltage applied and consequently, a reactor cannot be tested at no-load. Where sufficient power is available in the factory to permit full energization of reactors, the methods to be followed are the same as those for transformers. Alternatively, measurements may be made on-site
31、 if conditions are suitable. Unless otherwise specified, the tests shall be carried out with the tap-changer (if any) on the principal tapping. However, this tap position may not give the maximum sound level in service. In addition, when the transformer is in service, a superposition of the flux at
32、no-load conditions and the stray flux occurs which causes a change in the flux density in certain parts of the core. Therefore, under special conditions of intended application of a transformer (particularly variable flux voltage variation), it may be agreed to measure the sound levels on a tapping
33、other than the principal tapping, or with a voltage other than the rated voltage on an untapped winding. This shall be clearly indicated in the test report. 6.2 No-load current and rated voltage For measurements made on the test object with or without its auxiliary cooling plant, the test object sha
34、ll be on no-load and excited at the rated voltage of sinusoidal or practically sinusoidal waveform and rated frequency. The voltage shall be in accordance with 10.5 of IEC 60076-1. If a transformer is fitted with reactor-type on-load tap-changer equipment where the reactor may on certain tap-change
35、positions be permanently energized, the measure- ments shall be made with the transformer on a tapping which involves this condition and which is as near to the principal tapping as possible. The excitation voltage shall be appropriate to the tapping in use. This shall be clearly indicated in the te
36、st report. NOTE DC bias currents may cause a significant increase in the measured sound levels. Their presence may be verified by the existence of odd harmonics of the power frequency in the sound spectrum. The implications of increased sound levels due to d.c. bias currents should be taken into con
37、sideration by both the manufacturer and purchaser. For North American applications, the sound level tests shall be made at no-load in accordance with national requirements. The Standard is downloaded from Standard Sharing COPYRIGHT 5 6.3 Rated current and short-circuit voltage In order to decide wh
38、ether it is significant to perform load current sound measurements, the magnitude of the load current sound power level can be roughly estimated by equation (4): p r lg1839 INWA,S S L+ (4) where LWA,IN is the A-weighted sound power level of the transformer at rated current, rated frequency and imped
39、ance voltage; Sr is the rated power in megavolt amperes (MVA); Sp is the reference power (1 MVA). For auto-transformers and three winding transformers, the two winding rated power, St, is used instead of Sr. If LWA,IN is found to be 8 dB or more below the guaranteed sound power level, load current s
40、ound measurements are not appropriate. When these measurements are required, one winding shall be short-circuited and a sinusoidal voltage as defined in 10.5 of IEC 60076-1 applied to the other winding at the rated frequency. The voltage shall be gradually increased until rated current flows in the
41、short-circuited winding. 6.4 Reduced-load current If the measurements can only be performed at a reduced current, the sound power level at the rated current shall be calculated by equation (5): T N ITWA,INWA, lg40 I I LL+= (5) where LWA,IN is the A-weighted sound power level at rated current; LWA,IT
42、 is the A-weighted sound power level at reduced current; IN is the rated current; IT is the reduced current. The equation is valid for a reduced current of 70 % of the rated current. 7 Principal radiating surface 7.1 General The definition of the principal radiating surface depends on the type of co
43、oling auxiliaries employed and their position relative to the transformer. For the purpose of this standard, “cooling auxiliaries“ shall include forced air and forced oil cooling auxiliaries and water cooling equipment, and shall exclude natural air and natural oil cooling. COPYRIGHT 6 7.2 Transform
44、ers with or without cooling auxiliaries, dry-type transformers in enclosures and dry-type transformers with cooling auxiliaries inside the enclosure The principal radiating surface is the surface obtained by the vertical projection of a string contour encircling the equipment. The projection runs fr
45、om the top of the transformer tank cover (excluding bushings, turrets and other accessories situated above the tank cover) to the base of the tank. The principal radiating surface shall include cooling auxiliaries located 3 dB Repeat test a 8 dB(A), an alternative measurement method should be consid
46、ered. See Annex A. 13 Calculation of sound power level The A-weighted sound power level of the test object, LWA, shall be calculated from either the corrected average A-weighted sound pressure level, pA L, or the average A-weighted sound intensity level, IA L, according to equation (19) or (20), res
47、pectively: 0 pAWA lg10 S S LL+= (19) 0 IAWA lg10 S S LL+= (20) where S is derived from equation (6), (7), (8) or (9), as appropriate, and S0 is equal to the reference area (1 m2). For transformers with cooling auxiliaries mounted directly on the tank, the sound power level of the cooling auxiliaries
48、, LWA0, is given by equation (21): = WA2WA1 1 , 01 , 0 WA0 1010lg10 LL L (21) where LWA1 is the sound power level of the transformer and cooling auxiliaries; LWA2 is the sound power level of the transformer. NOTE If the sound power levels of the individual fans and pumps of the cooling auxiliaries a
49、re known, the total sound power level of the cooling auxiliaries can be obtained by adding together the individual values on an energy basis. This method of determining the sound power level of cooling auxiliaries is subject to agreement between manufacturer and purchaser. For transformers with cooling auxiliaries mounted on a separate structure, the sound power level of the transformer plus cooling auxiliaries, L WA1, is calculated by using equation (22): += WA2WA0 1 , 01 , 0 WA1 1