FREJA is a unique relay test system primarily intended for field testing. It is therefore built up as a complete portable work station that is easy to transport. FREJA combines a computer with a test unit for m~nual and automatic testing. The test unit is controlled by a portable personal computer. No additional instruments are needed for testing or for test planning. FREJA can be used for the testing of most types of relays. The test system provides three voltage and three current outputs that can be controlled individually or controlled with respect to each other. The test system is supplied from a single phase source, 1151230 V aG, 50/60 Hz. The output quantities of the test system are independent of the supply source, e.g. the test system can give out voltages with 16 2/3 Hz or 60 Hz frequency even when supplied from ~50 Hz source. Display panels for the- simulation of different types of faults are prepared for distance relays. For the testing of simpler types of relays such as overcurrent, voltageand directional relays a general display panel is available where the amplitude and phase angle for each current and voltage is controlled manually. For test of a relay’s performance to harmonics there is an extended general display available there the fundamental voltage and/or current can be superimposed by two harmonics. Displays are also available for test of frequency, synchrocheck and synchronizing relays. When used for manual testing the test system operates as a conventionai test set, but is much easier and faster to use. The controls of a normal instrument panel are presented on the PC display, i.e. with a display panel. When testing a distance protectian. the applied fault impedance is shown in an impedance diagram on the display. The test quantities can be varied and observed directly in the impedance diagram presented as an oscilloscope screen.