Calculating loadability limits of distance relays

Over the years, different methods have been used in order to avoid problems with load encroachment, and each method presents its own set of advantages and disadvantages. Regardless of the method used, each relay will have a maximum "loadability limit" that will cause the relay to operate under high load conditions. Therefore, it is important for the relay engineer to understand and take time to calculate the maximum loadability limits of the relay so as to avoid settings that will be susceptible to load encroachments. This technical document focuses on concepts, definitions and calculations to find the maximum loadability limit of a distance relay with mho and lens characteristics.