The paper presents work with the Siemens DIGSI 5 software package, using the example of a numerical relay device for differential protection of a power transformer, as an introduction to the use of digital twin technology for the virtualization of numerical relay devices in the cloud. The method of parameterization of the aforementioned relay device using the DIGSI 5 program is described in detail. In addition, the method of its testing, which was performed using the Omicron CMC test device, is also presented.