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机器作为声源所辐射的声功率级可分成二部份:一、机器表面振动所辐射的声功率级;二、机器通风系统所辐射的声功率级。但通过机器表面振动速度级的测量来计算振动声功率级的辐射,必须搞清辐射效率,经研究证明,辐射效率的关系可以由A计权特性取代。因此,只要在电机的测量面上,按规定的测点位置数用A计权测量各点的振动速度(有效值),确定A计权平均速度级;用声级计测量进风口的平均声级,即可计算电机的声功率。下面介绍测量方法和计算公式。一、测量前的准备 1.测量仪器 (1)振动速度的测量仪器要求带A计权网络,频率响应范围应为10赫至10000赫,在此频率范围内的相对灵敏度以80赫的相对灵敏度为基准,其他频率的相对灵敏度应在基准灵敏度的+10％至-20％的范围以内。
The sound power level radiated by the machine as a sound source can be divided into two parts: the sound power level radiated by the machine surface vibration; and the sound power level radiated by the machine ventilation system. However, it is necessary to find out the radiation efficiency by calculating the vibrational power level radiation through the measurement of the vibration velocity level of the machine surface. It has been proved through studies that the radiation efficiency can be replaced by the A-weighted property. Therefore, as long as the motor measurement surface, according to the provisions of the number of measuring points with A-weighted measurement of the vibration speed of each point (RMS), to determine the A weighted average speed level; sound level meter to measure the average air inlet Level, you can calculate the sound power of the motor. The following describes the measurement method and calculation formula. First, the measurement before the preparation 1. Measuring instruments (1) vibration velocity measuring instrument requires a weighted network with A, the frequency response range should be 10 Hz to 10000 Hz, the relative sensitivity in this frequency range 80 Hz relative sensitivity As a guideline, the relative sensitivity of other frequencies should be within the range of + 10% to -20% of the reference sensitivity.