In consideration of the fact that traditional primary equipments, such as transformers, have a variety of different interfaces and communication protocols, and cannot be applied to the intelligent substation system. A method of "traditional primary equipment smart component" can be used to solve the problem .A smart component supports the services of IEC61850 standard and outputs data based on the standard. Then a traditional equipment can be used in the intelligent system through smart component and run compatibly. This paper discusses a smart component, which converts the traditional communication protocol of transformer acquisition device to IEC61850 protocol, and introduces its working principle, hardware structure and software. Finally, the correctness of the protocol conversion is verified.