IEC TR 63396:2021 pdf download – Noise measurement method on power capacitors.
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. IEC 61 260-1 :201 4, Electroacoustics – Octave-band and fractional-octave-band filters – Part 1: Specifications IEC 61 672-1 :201 3, Electroacoustics – Sound level meters – Part 1: Specifications ISO 3744:201 0, 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 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 noise unwanted sound [SOURCE: IEC TS 61 973:201 2, 3.1 .1 3]
The controlled deviation of the amplitude of injected fundamental current and harmonic currents of each order is not greater than 3 %. Typical test circuits for shunt capacitor units noise measurement are documented in Figure B.1 in Annex B. 4.1.2 Current injection conditions for AC filter capacitor units During a noise test of AC filter capacitor units, both fundamental current and harmonic currents that are specified for test are injected simultaneously, if practicable. The controlled deviation of the amplitude of injected fundamental current and harmonic currents of each order are not greater than 3 %. Typical test circuits for AC filter capacitor units noise measurement are documented in Figure B.1 . 4.1.3 Current and voltage injection conditions for DC filter capacitor units During a noise test on DC filter capacitor units, both DC voltage and harmonic currents that are specified for test are injected simultaneously, if practicable. The controlled deviation of the amplitude of DC voltage and harmonic currents of each order injected are not greater than 3 %. Typical test circuits for DC filter capacitor units noise measurement are documented in Figure B.2. 4.2 Measuring environment Noise measurement on power capacitor units is carried out in hemi-anechoic rooms meeting the qualifications described in Annex A or Annex B of ISO 3744:201 2. Environments with background noise not more than 30 dB and without acoustic wave reflection that affects appreciably the measurement results are acceptable alternatives.
The background noise at each measuring point is measured before and after noise measurement, and the difference between the two average sound pressure levels is maintained within 3 dB. It is preferable that the background A-weighted sound pressure level be at least 1 0 dB lower than the power capacitor’s sound under the specified test conditions. When these conditions are not satisfied, at least the method given in 4.6.2 is followed. 4.3 Characteristics for basic acoustic instruments The sound meters used for measuring sound pressure levels are compliant with the characteristics set out in IEC 61 672-1 :201 3, class 1 , and they are calibrated according to ISO 3744:201 0. The octave or one-third-octave band filters are selected so as to meet the requirements specified in IEC 61 260-1 :201 4. 4.4 Arrangement of the power capacitors The arrangement mode of the test object is such to be consistent with the installation and design requirements of actual projects. A fixing method that basically does not affect the generation and propagation of power capacitor noise is adopted. Generally, the power capacitor unit is fixed to a rack as in the actual installation.
4.5 Arrangement of the microphone The microphone is positioned close to the measurement surface. The number and position of the microphones are described in Annex A. 4.6 Measurement on sound pressure levels 4.6.1 General The measurement is made when the background noise level is approximately constant.