Modern trends in the design of electrical machines aim to increase efficiency, i.e. to improve the technology of electrical machine production. This in turn leads to a reduction in the volume and a reduction in the thermal time constants of the electrical machine. As the electrical machines in modern industrial plants are operated more and more dynamically, this leads to faster overheating of the motor in the event of an overload, which is particularly pronounced in heavy electric motor drives (EMD). High voltage (HV) Squirrel Cage Induction Motors (SCIM) are designed for particularly high loads and have very low permissible overloads for use in heavy duty applications. There are a number of different factors that affect the operation of HV SCIM and a deviation from any of these factors can result in damage to the motor. In modern industrial plants, various forms of motor protection have been developed to prevent the occurrence of failures or to reduce the damage to the production process. The damage caused by stopping the production process driven by HV SCIM is usually many times more expensive than the damage caused by destroying the motor due to a failure. Therefore, it's necessary to assess the condition of the failed motor and extend its operation until replacement drives are available. The most common protective measures used in practise are the use of numerical relays due to their simpler operation, lower cost and more robust construction. The dissertation presents the use of numerical relays as an existing control device for HV SCIM protection, to which we can activate an additional predictive protection function to create conditions for state evaluation of heavy electric motor drives with HV SCIM. This increases the reliability of the system with negligible investment in the existing management and protection infrastructure. Theoretical settings of dynamic modes of heavy EMD driven by HV SCIM, influences of the power supply network and expert knowledge from research on failures and transient operating modes are presented. Current diagnostic methods for fault location are presented, in particular on-line methods and the application of numerical protection relays in the condition assessment of heavy EMD driven by HV SCIM..