Turn fault detection
AssigneeGeneral Electric Company
InventorGerald B. Kliman
Life of this patent
Estimating the term…
Abstract
A method for detecting turn faults in an induction motor comprises measuring at least two motor phase currents, at least two motor phase voltages, and the negative sequence impedance. Motor torque is estimated by employing the at least two motor phase currents and the at least two motor phase voltages. Motor pu slip is estimated by employing the motor torque. The motor pu slip is used to estimate the load variation effect on the negative sequence impedance. The negative sequence impedance is adjusted in accordance with the load variation effect, and it is determined whether the adjusted negative sequence impedance value indicates the presence of a turn fault.
Claims20
A method for detecting turn faults in an induction motor comprising the steps of:
- measuring at least two motor phase currents;
- measuring at least two motor phase voltages;
- employing the at least two motor phase currents and the at least two motor phase voltages to estimate the negative sequence impedance;
- employing the at least two motor phase currents and the at least two motor phase voltages to estimate motor torque;
- employing the motor torque to estimate motor pu slip;
- employing the motor pu slip to estimate load variation effect on the negative sequence impedance;
- adjusting the negative sequence impedance in accordance with the load variation effect;
- and
- determining whether the adjusted negative sequence impedance value indicates the presence of a turn fault.
A method for detecting turn faults in a three-phase motor comprising the steps of:
- measuring at least two motor phase currents;
- converting the at least two motor phase currents into three digital phase current signals;
- measuring at least two motor phase voltages;
- converting the at least two motor phase voltages into three digital phase voltage signals;
- employing the three digital phase current signals and the three digital phase voltage signals to estimate the negative sequence impedance;
- employing the three digital phase current signals and the three digital phase voltage signals to estimate motor torque;
- employing the motor torque to estimate motor pu slip;
- employing the pu slip to estimate the amount of negative sequence impedance attributable to the motor load;
- subtracting the attributable amount of negative sequence impedance from the estimated negative sequence impedance to obtain an adjusted negative sequence impedance in accordance with the load variation effect;
- and
- determining whether the adjusted negative sequence impedance value indicates the presence of a turn fault.
An apparatus for detecting turn faults in an induction motor comprising:
- at least two current sensors for measuring at least two motor phase currents;
- at least two voltage sensors for measuring at least two motor phase voltages;
- means for employing the at least two motor phase currents and the at least two motor phase voltages to estimate the negative sequence impedance;
- means for employing the at least two motor phase currents and the at least two motor phase voltages to estimate motor torque;
- means for employing the motor torque to estimate motor pu slip;
- means for employing the motor pu slip to estimate load variation effect on the negative sequence impedance;
- means for adjusting the negative sequence impedance in accordance with the load variation effect;
- and
- means for determining whether the adjusted negative sequence impedance value indicates the presence of a turn fault.
Dependencies are inferred from the claim text.