IEC TR 63396-2021 Noise measurement method on power capacitors

IEC TR 63396-2021 Noise measurement method on power capacitors. 4 Noise measurement 4.1 Power injection conditions for capacitors 4.1 .1 Current injection conditions for shunt capacitor units The maximum injection current of shunt capacitor units is applied as follows: a) Fundamental current is not greater than 1 ,1 I e , where I e is the rated current for the capacitor unit. b) The root mean square value of fundamental current and harmonic currents is not greater than 1 ,3I e . During noise test of shunt capacitor units, both fundamental current and harmonic currents that specified for test are injected simultaneously, if practicable. 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...