In the intranet network distribution area there is a need to develop a large number of specific specialist energy applications to solving the everyday needs of engineers or management of electricity networks. These applications are developed to meet specific requirements which can have an advanced intranet user, and can't realize an complex GIS, TIS and Document-Managment system (GTDM), which exist in a similar environment. These "big and complex" systems are used primarily for building and maintaining databases, while making an application for a "specific purpose" is left to other "minor" applicative environments.The master thesis deals with examples of different implementations of similar solutions in the Internet network, are compared the possible solutions and provided specific GUIdance. Also, is treated more examples of solving specific problems using these energy applications. The emphasis is put on the current actual transfer medium power network (Zagreb) with voltage 10kV distribution voltage to 20kV voltage. Because of the trend growth in demand of electricity lines and cables that work on the operating voltage of 10 kV are increasingly loaded by current. The result is the high voltage drops and losses in the network so increasingly is working on the transition of the medium network voltage to 20kV. This transition is extremely demanding in Zagreb, because of the dense electrical network and inappropriate degrees of isolation of individual network elements. For this purpose, are upgraded the existing applications, so that at any moment can be seen which part of the medium voltage network must be upgraded or replaced (insulation voltage). Using the new applications at any moment it is possible quickly register which part of the network was converted to 20kV, and which part is still working on 10KV voltage (operating voltage). Upgraded is the existing applications for data entry (TIS) on network elements and intranet application for the maintenance of graphical database "Single line diagram MV network of the City Zagreb." The master thesis should on these concrete examples demonstrate the importance of such specialist energy intranet applications, and directly benefit from those that have employees in the distribution company to deal with everyday tasks. In addition, this master thesis should give some guidance in the systematization and selection the most suitable environment for the development of similar applications, and set the requirements that they must meet when integrating into other areas within the distribution of HEP.