In the last two decades it has become a requirement for intelligent electrical devices (IEDs) in the power distribution industry to be able to communicate with other substation automation equipment, so they can present measurands and events to SCADA systems and be controllable by substation control devices. During the years countless communication protocols have emerged,
which used vendor specific and proprietary solutions, thus interoperability became inconceivable. Numerous efforts have been
made to come up with a unified communication protocol, out of which IEC 60870, IEC 61850, Modbus and DNP3 where created. The subject of this thesis is the introduction of DNP3 (Distributed Network Protocol 3) and its implementation into Protecta LTD.'s
Europrot+ numeric protection platform. Parallel to this, a master simulation software has been developed, which was used for evaluating interoperability and conformance to the standard. The layers of the protocol are described one-by-one, after which the corresponding source codes are introduced and explained.