New Tier 3 acoustic generator set packages offer significant sound attenuation

Dec. 12, 2007
Cummins Power Generation Inc. has introduced a new series of 100, 125 and 150 kW Tier 3 generator sets with advanced sound-attenuated enclosure systems. With a sound level of only 67.5 dB(A), the 100 kW unit is one of the quietest generator sets available at that power node from a generator manufacturer. Available in steel or aluminum with two levels of sound attenuation, the generator set and enclosure packages are intended for all-weather outdoor use wherever local ordinances or circumstances require sound abatement. In addition to sound-attenuated enclosures, Cummins Power Generation also offers weather-protective generator set enclosures. “This new quiet generation of sound-attenuated generators and enclosures makes it easier for specifying engineers and end-users to meet even severe noise abatement requirements,” says Vivek Malapati, product marketing manager, Cummins Power Generation. “These generator set packages utilize our EPA Tier 3-certified generator sets featuring the Cummins QSB7 diesel engine. Combined with low-emissions generator sets, the new sound-attenuated packages are another demonstration of Cummins Power Generation’s commitment to providing power systems that minimize environmental impact,” he says. “These new quiet generator set packages are our response to customer requests for generator sets that can comply with increasingly stringent local noise ordinances.” Two levels of sound attenuation The generator set and enclosure packages are available in two levels of attenuation. The quieter sound-attenuation package features an enhanced exhaust silencer and steel construction with sound-absorbing material. This limits sound levels to 67.5 dB(A) for the 100 kW generator set package; 68.6 dB(A) for the 125 kW generator set package; and 69.6 dB(A) for the 150 kW generator set package (measured at 23 feet [7 meters] with the generator set operating at full rated load). The weather-protective generator set enclosure package includes an industrial exhaust silencer and 14-gauge steel construction without added sound-absorbing features. In addition to the quiet Tier 3-certified Cummins QSB7 engine with its larger cooling system and reduced combustion noise, the cooling airflow through the enclosure has been routed to reduce the sound from air movement. By bringing the cooling air in behind the alternator and then routing it over the engine and radiator so that it exits upwards out of the enclosure, a torturous path is created that reduces high-frequency sound. “Cooling air movement has always been a significant source of generator set noise, and by making it turn 90 degrees twice, we have been able to eliminate some high-frequency components,” says Malapati. The design also allows for the enclosed generator packages to run at full standby load in up to 127 degrees F (53 degrees C) ambient air temperature. This will provide a factory solution for customers that need generator sets to operate in high-temperature environments. In addition to sound-attenuating features, the enclosures are designed with convenient access doors for the engine and alternator service points. Fork lift pockets on the skid base and built-in two-point lifting brackets simplify installation at the job site.