What might be indicated if a harmonic frequency is detected at one of the sidebands?

When a harmonic frequency is detected at one of the sidebands in vibration analysis, it strongly indicates that the machine is experiencing a fault. Harmonics are integer multiples of a fundamental frequency and their presence at sidebands often signifies a nonlinear condition within the machine, such as unbalance, misalignment, or mechanical looseness. The detection of these frequencies is essential for fault diagnosis, as they typically point to an underlying issue that could affect machine performance and reliability. In a healthy machine operating normally, one would not expect to see such harmonic frequencies at the sidebands, as they are indicative of disturbances in the operation. Thus, their detection is a crucial signal for practitioners to investigate further into the condition of the machinery.