Operation and design of a protection relay for transformer condition monitoring

Transformers are critical to the successful operation of the electrical power systems. Their reliability and availability is therefore key to flawless and optimum power generation and transmission. Effective condition monitoring is essential to evaluate transformer performance and safe operating conditions. Over the past few years many stand-alone devices have been developed for transformer condition monitoring. However, modern protection relays can offer an economic solution for condition monitoring as well as providing the required protection functionality and integration into the control system. This paper describes the operation and design of a transformer protection relay that includes many of the common transformer condition monitoring features required. The paper also discusses the standard ancillary features of the protection relay such as the flexible industry standard communications options, such as IEC 61850 over Ethernet, allowing easy integration in the network control system and programmable scheme logic providing easy logic customization as well as the user friendly event and disturbance recording features that can help diagnosing faults.