A method for monitoring a system having an electrical connection, the connection having at least two phases and respective currents, the system having a periodic behavior, the method comprising the steps of: creating a current transformer-related database corresponding to component features of proper functioning of the system, the current database created during operation of the system or created in advance of system operation; connecting sensors to measure respective currents of two phases of the electrical connection and transferring the measured current information to a PC host; using the PC host to transform the measured currents and to create initial current information whereby the initial current information includes: a normalized correlation frequency spectrum, derived from the cross power spectrum of the at least two phases; a non-trivial frequency spectrum derived from the normalized frequency spectrum; and a root-mean-square calculation of the non-trivial frequency spectrum; making an initial determination of a normal operation of the system, by performing an initial threshold check whereby the root mean-square of the non-trivial spectrum is compared to a threshold value derived from the current database, using the PC host, and stopping and giving an indication of a fault/abnormal system operation if the initial threshold check is not successful; operating the PC host to perform training and modeling of the system, following successful initial determination of normal operation of the system, the training and modeling of the system including further current measurements yielding modeled current information; monitoring the system, which includes performing instant current measurements of the system and using the PC host to yield instant current information indicative of instant operation status of the system; and making an instant determination of operation status of the system by using the PC host to compare the instant current information with the modeled current information. creating a current transformer-related database corresponding to component features of proper functioning of the system, the current database created during operation of the system or created in advance of system operation; connecting sensors to measure respective currents of two phases of the electrical connection and transferring the measured current information to a PC host; using the PC host to transform the measured currents and to create initial current information whereby the initial current information includes: a normalized correlation frequency spectrum, derived from the cross power spectrum of the at least two phases; a non-trivial frequency spectrum derived from the normalized frequency spectrum; and a root-mean-square calculation of the non-trivial frequency spectrum; making an initial determination of a normal operation of the system, by performing an initial threshold check whereby the root mean-square of the non-trivial spectrum is compared to a threshold value derived from the current database, using the PC host, and stopping and giving an indication of a fault/abnormal system operation if the initial threshold check is not successful; operating the PC host to perform training and modeling of the system, following successful initial determination of normal operation of the system, the training and modeling of the system including further current measurements yielding modeled current information; monitoring the system, which includes performing instant current measurements of the system and using the PC host to yield instant current information indicative of instant operation status of the system; and making an instant determination of operation status of the system by using the PC host to compare the instant current information with the modeled current information.