Strategic Motor Condition Based Operating Management
The Anomalert motor monitoring unit is a power measuring device that continuously monitors motor absorbed power and current and compares the operational parameters to known fault signatures and to a learned normal operating model of the machine. The power density spectrum and measured current deviation from the model permits early detection of developing anomalies including Loose foundation components, unbalance and misalignment, transmission element, Bearings, Stator and rotor, internal and external electrical anomalies which incorporates the supply, motor and the driven equipment.
This instrumentation has been installed on three 5500kW 11kV mill motors and the main feed conveyor motor at the concentrator.
Internal electrical anomalies were identified on the ball mill motor at an alarm 1 level which prompted a visual inspection to quantify the cause. Early stator wedge failure was identified and the significance was considered with respect to operating risk and condition monitoring towards a planned forward outage when the motor could be replaced with the spare. The knowledge of this failure mechanism, vigilant trending and a further inspection to assess rate of deterioration managed to keep the motor in service for 6 months to a planned outage for motor chang-out.
The replaced ball mill motor experienced a hang up of some of the brushes on the centre slipring which was detected by the anomalert as an internal electrical fault. This fault condition deteriorated very quickly requiring an emergency stop of the mill.
Both experiences described above are presented showing the Anomalert diagnosis and trended status leading up to the planned outage in case 1 and forced shutdown in case 2.
The cases describe how knowledge of machine condition is used to manage operating integrity towards a planned maintenance intervention before catastrophic failure occurs.