This method allows North American users to define phase shift by simply determining how the delta is made up on A-phase (Delta AB or Delta AC ). If the relay is being used to protect an IEC standard transformer, a custom mode can be selected that uses the 30บ clock. This results in a less-complicated method to communicate transformer phase shift to a digital relay for a standard IEEE/ANSI phasing application while still providing the flexibility to address IEC transformers. Figure 8 illustrates this software.