System and method of detecting cavitation in pumps

A method of detecting cavitation in a pump driven by an electric motor, the method comprising:

• accessing motor current data corresponding to a motor controlled by a variable frequency drive;
• generating modified motor current data having a fundamental frequency removed therefrom;
• performing a frequency spectrum analysis on the modified motor current data to generate a plurality of current frequency spectrums;
• generating a plurality of fault index samples from the plurality of current frequency spectrums over a period of operation of the motor, wherein a respective fault index sample of the plurality of fault index samples comprises a ratio of a current magnitude in a first portion of a respective current frequency spectrum to a current magnitude in a second portion of the respective current frequency spectrum;
• calculating a cavitation threshold using historical fault index samples of the plurality of fault index samples;
• and
• generating an alarm if a real-time fault index sample of the plurality of fault index samples is greater than the cavitation threshold.

A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions which, when executed by at least one processor, cause the at least one processor to:

• receive current data from a sensor system coupled to a motor/pump system;
• condition the current data;
• generate a frequency spectrum of the current data;
• extract a fault signature and a reference signature from the frequency spectrum, the fault signature and the reference signature representative of a load condition and an operating frequency of the motor/pump system;
• calculate a fault index using the fault signature and the reference signature;
• compare the fault index to a fault threshold;
• and
• generate an alarm if the fault index is greater than the fault threshold.

A controller configured to monitor pump cavitation having a processor programmed to:

• repeatedly receive real-time operating current data from a motor driving a pump;
• generate a current frequency spectrum from the current data;
• analyze current data within a pair of signature frequency bands of the current frequency spectrum;
• repeatedly determine fault signatures as a function of the current data within the pair of signature frequency bands;
• repeatedly determine fault indices based on the fault signatures and a dynamic reference signature;
• compare the fault indices to a reference index;
• identify a cavitation condition based on a comparison between the reference index and a current fault index;
• calculate the reference index from a plurality of fault indices acquired over a period of operation of the motor;
• identify a pre-determined percentage of fault indices acquired over the period of operation of the motor having a smallest value;
• and
• calculate a mean of the pre-determined percentage of fault indices acquired over the period of operation of the motor having the smallest value to generate the reference index.

A controller configured to monitor pump cavitation having a processor programmed to:

• repeatedly receive real-time operating current data from a motor driving a pump;
• generate a current frequency spectrum from the current data;
• analyze current data within a pair of signature frequency bands of the current frequency spectrum;
• repeatedly determine fault signatures as a function of the current data within the pair of signature frequency bands;
• repeatedly determine fault indices based on the fault signatures and a dynamic reference signature;
• compare the fault indices to a reference index;
• identify a cavitation condition based on a comparison between the reference index and a current fault index;
• calculate the reference index from a plurality of fault indices acquired over a period of operation of the motor;
• update the reference index after one of a preset time period of motor operation and a determination of a preset number of fault indices;
• and
• update the reference index using a number of fault indices having values less than the reference index.