## 5 Experimental Tests of SOM Classifiers of IM Winding Faults
### Results of Stator and Rotor Fault Classification  
The experimental verification of the obtained networks was carried out for the classification of rotor and stator winding failures and for mixed damage. In addition, the effect of the no-load machine's operation on the fault classification process of the broken rotor bars was checked. On the basis of the network response to the training vector, map zones indicating the technical condition of the electric circuits of the tested motor were highlighted. In the following figures the responses of the KN to test data not included in the learning process are demonstrated. The data were collated in a tabular form to show the impact of motor operating conditions on the failure classification efficiency. In Figure 12a the classification of the rotor cage damage of the tested IM, for different load torques and supply frequencies, using 10 \(\times\) 10 map is shown. The neuron numbers (1-12) are used to read properly the test measurement parameters in the adjacent table (Figure 12b). An example of proper reading the results presented in following figures is marked at Figure 12. It can be seen that the designed SOM maintains a high level of the failure classification of the rotor bars in the case of changes in the machine's operating conditions. It should be mentioned that as a result of the increase in the load torque, the neurons located in the upper part of the Kohonen map are active. The changes in the frequency of the supply voltage do not affect the classification process of the rotor bar damage. Active neurons are located in areas characteristic of the rotor damage. The areas of the Kohonen map marked with a dotted line do not coincide with the zones characteristic of the stator faults (hatched areas in the Figure 12a). The part of the map characteristic of the lack of motor damage was clearly distinguished. As observed in Figure 12b, some neurons were assigned to the same number despite the fact that they represent different state of machine operation. The overlapping of neurons is a result of similar changes in the signal for several incidents of damage belonging to the same category. A similar situation is observed in results of fault classification in the following figures. Figure 11: Influence of the number of training epochs to the SOM neighbourhood distances: (**a**) 600 training epochs; (**b**) 200 training epochs. Figure 13 shows the NN responses in the case of short-circuits in the stator windings (Figure 13a) and simultaneous failure of the rotor and stator of the induction motor (Figure 13b). The conditions for the measured test data for the map shown in Figure 13a are included in the table in Figure 14. In the case of mixed damage, Figure 13b shows possible combinations of failures for the constant value of the supply voltage \(f_{s}\) = 50 Hz and load variations in the range (\(T_{L}/T_{LN}\) = 0.5 \(\div\) 1). Figure 12: Classification of the rotor cage damage of the induction motor: (**a**) Kohonen map 10 \(\times\) 10: dotted lines—IM damage categories involved in the classification, hatched areas—IM damage categories not involved in the classification; (**b**) specification of test data parameters; \(T_{L}\)—load torque, \(T_{LN}\)—rated motor torque, \(f_{s}\)—frequency of the supply voltage, \(N_{sh}\) —number of shorted turns in the stator winding. IM: induction motor. Figure 13: Classification of the induction motor failures: (**a**) stator windings faults: dotted lines—IM damage categories involved in the classification, hatched areas—IM damage categories not involved in the classification; (**b**) mixed faults: dotted lines—IM damage categories not involved in the classification; 10 \(\times\) 10 SOM; \(N_{sh}\)—number of shorted turns in the stator winding, \(N_{sh}\)—number of broken rotor bars. The responses of the Kohonen network to the testing patterns, shown in Figure 13a in the case of ITSC faults, provide information about both the type of damage and the degradation scale of the stator windings.