Setting calculation of asynchronous regime liquidation devices can be very difficult as a result of variable power system parameters. Therefore, efficiency of action operation and correctness of setting must be tested by experience in various regimes of power system work. For asynchronous regimes such signals are typical which form it is difficult to recreate using traditional relay testing technique, so, these signals of testing are obtained by modelling of various regimes of power system work processes. For modelling processes a software EUROSTAG is used. Signals calculated by EUROSTAG software as a result of asynchronous regime modelling in power system are represented with signal effective value and phase angle. It is impossible to use them directly to test real protection and automation device operation. Specific software was created that converts modelling signals into COMTRADE format after what signals are transformed in real current and voltage variables used for devices testing. EUROSTAG dynamical process simulation software was successfully implemented in automation device testing. As tested device, asynchronous regime liquidation device in AGNA power system was chosen. In the result of testing AGNA relay operability in various modelling regimes of power system work with specified setting of device was confirmed. Methodology of device testing using modelled signals makes it possible to test asynchronous regime liquidation device operability in close-to-real conditions and may be used for testing of other relaying protection and automation devices.