## 4 Discussion
It should be taken into account that the investigations of the effect of asymmetry of the feed system and asymmetry of the motor stator windings on the starting characteristics were conducted for the steady-state mode. The investigations of the effect of asymmetry of the feed system and asymmetry of the motor stator windings on the starting characteristics were not conducted for the conditions of transient processes caused by a variation in the values of feed voltage and load on the traction drive shaft. This presents certain limitations to the application of the scheme developed. Additional investigations are conducted in order to account for the above factors. At the same time, the authors realized the difficulties related to retrieval of the experimental data under the conditions of operation of an electric locomotive. In the process of work on the present paper, the authors encountered objective difficulties related to the absence of any possibility to conduct a full-scale experiment and retrieve valid experimental data. This is related to the fact that the control systems are the microprocessor-type systems by design. In order to read the experimental waveforms of the signals at the output of \"Observer of torque and flux\", it is necessary to obtain the authorization of the system manufacturers. This is difficult to implement as it relates to trade secrets. There are some important caveats to this study that deserve mention:  
The investigations of the effect of asymmetry of the feed system and asymmetry of the motor stator windings on the starting characteristics were not conducted for the conditions of transient processes caused by a variation in the values of feed voltage and load on the traction drive shaft. This could raise the question of the correctness of the location identification of the defect that influences the occurrence of asymmetric emergency modes. The mode of wheel slippage attempt by one-wheel pair was chosen for the investigation of the effect of a variation in the motor shaft load on the starting characteristics. To simulate this process as the driver effect, a rectangular pulse sequence was proposed. In real operating conditions, this process may be stochastic. The stochastic process of variation of the load may also be subject to the effect of operational parameters such as dynamic oscillations in the wagons under the variation of the nature of work of the electric locomotive, which were not taken into account during the investigations. The following extensions to the investigation could be conducted:  
Investigation of the stochastic effect of the variation of voltage in the catenary system on the operation of the system of diagnostics of the asymmetric emergency modes in the DTC traction drive system;  
Investigation of the effect of thermal noise of the autonomous voltage inverter on the operation of the system of diagnostics of the asymmetric emergency modes in the DTC traction drive system;  
Investigation of the thermal noise of the windings of traction motor windings on the operation of the system of diagnostics of asymmetric emergency modes in the DTC traction drive system;  
Investigation of the stochastic character of the variation in load of the traction drive on the operation of the system of diagnostics of the asymmetric emergency modes in the DTC traction drive system;  
Investigations of the effect of asymmetry of the feed system and asymmetry of the motor stator windings on the starting characteristics for the conditions of transient processes caused by a stochastic variation in the values of feed voltage and load on the traction drive shaft.