Cloggage Detection of a Wastewater Pump based on Motor Current Analysis

In the area of condition monitoring, the use of motor signals to determine the condition of external motor components (load, coupling drive…) is getting increasing attention. In the case of motors driving submersible pumps, a typical problem is cloggage of the pump impeller. According to the state of the art, only few condition-based maintenance approaches have been applied to detect this problem. In this paper, an approach for cloggage diagnosis is proposed that is based on the spectral analysis of the motor current. It is shown that cloggage influences two frequencies in the current spectrum in particular. Both stationary and transient analyses can be used to detect the cloggage, which is shown based on the analysis of laboratory data. As a test object, a 7.7 kW submersible motorpump set was measured in a defined test procedure that included cloggage and manual deragging of the pump.