Many utilities create custom relay logic for their specific needs and desired operation of their substations. However, comprehensive relay logic testing may not be done before issuing the relay settings to field. At some utilities, RTDS relay testing is done for standard logic prior to issuing files to field but there are often changes with brown field installations, so specific applications for each project are issued untested. At other utilities testing may be left entirely to the field. Therefore, relay testing is typically performed in the field at the very end stages of a project. The field test may not be comprehensive either due to shortage of time or abundance of scenarios to be tested. The settings (along with logic in them) produced in such conditions pave the way to misoperation that present hazard to the public and utility workers. We propose to develop a Virtual Logic Test Software (VLTS) which an engineer can utilize to develop and interactively test the custom logic such that the engineer will confirm the desired operation on a simulation one-line before issuing the settings file. VLTS will enable testing of all the relay functions rather than a few common limited scenarios in a fraction of time it would take on RTDS or field test. Using VLTS, electric utilities will also be able investigate inaccuracies in relays that are already in service to prevent a potential false operation waiting to occur. By the end of Phase II, user will be able to directly import logic from the relay setting files (i.e. SELâs .rdb files) into VLTS. Once converted in graphical format, the user will then be able to analyze individual bits and/or outputs in detail as well as the operation on a simulation one-line to verify the proper operation of the relays in the station. We limit our scope in Phase I to SEL Relays because our first potential customer, PPL Electric Utilities, utilizes SEL relays. We will expand the software capabilities, other relays manufacturers and fault study programs in Phase II. The proposed tool will provide a myriad of benefits to the public: Customers will experience no blackouts caused by inaccurate or incomplete relay logic. Power utilities themselves will have significant savings because of not having the blackout, but more importantly not having to fix the improper logic or the damage it may have caused. This in turn will reduce transmission and distribution cost to the end customer. Ability to virtually test existing installations will enable the power utility to identify relays that have erroneous logic, waiting to cause a misoperation