Fan blades and centrifugal pump vane frequencies can be monitored in a demodulated current spectrum at a frequency that is equal to the number of blades (or vanes) times the pole pass frequency (FP). Increasing amplitude at this frequency as well as a possible increase at the motor speed frequency peak is an indication of possible blade or pump vane damage. After initial installation or verification that the pump or fan is in satisfactory condition, identify the vane frequency and record the amplitude of the peak. With baseline amplitude for the equipment established, the demodulated current spectrum is used as a simple and efficient method to monitor the equipment.

Tip provided by: PdMA Corporation