An Active Control Device for Electric Power Plant

The large electric power generators are powered by diesel engines which produce very high noise levels, usually attenuated by passive mufflers systems, installed along the engines exhaust channels. In this paper, a new active noise control device is proposed, designed to be used in addition to the common passive mufflers ssystems, in order to achive a more elevated attenuation of noise. The device is made up by a box, which contains two power loudspeakers fed by a control circuit, that generates an electrical signal, teh spectral features of which are derived by picking up the electricity produced by the power generator. The acoustic signal emitted by the loudspeakers has the same shape but opposite phase of the signal produced by the engine. The two signals interfere across the final section of the engine exhaust pipe. The device has been installed on a power generator of a telephone exchange station: a noise reduction of about 20 dB was obtained. Furthermore, the mostly attenuated frequency range is 40-200 Hz, where the common passive mufflers systems show a very low efficiency.