No-Load to Full-Load Airborne Noise Level Change on High-Speed Polyphase Induction Motors

Noise and its effects on hearing preservation, working efficiency, and related physiological and psychological areas has resulted in legislation and motor specifications wherein maximum airborne noise level limits are imposed. Traditionally, motor noise levels have been specified by the purchaser and guaranteed and tested for by the manufacturer with the motor operating at no load, with rated voltage and frequency applied and having a ``soft'' environment surrounding the machine. Ideally, motor noise levels under load in the actual installation environment are the performance data required. This paper presents test data intending to concretely answer at least one of the unknowns-that being the change in motor noise level between no-load and full-load operation within a defined environment. Compelling data are also advanced on the effects of the acoustic environment on noise measurements.