POWER provided Real Time Digital Simulator (RTDS) testing of new line protection relay settings required with the addition of a substation to a leading utility’s transmission network. The substation was a new switching station that connects eight 345 kV transmission lines with remote terminations at two different utilities’ substations. Due to uncertain transient effects of the series capacitors during fault events, the utility required RTDS testing of the settings applied to line protection at both ends of all eight lines. POWER developed the RTDS power system model from data provided by the client. POWER calculated relay settings at each line terminal for RTDS testing. Simulated faults were applied at various locations under various load flow conditions. Fault locations were selected to give the relaying system the most challenging conditions. If relays operated incorrectly, results were analyzed and POWER provided recommended settings or scheme design changes to correct the issue.