The principle of precise fault location using traveling waves on transmission lines is well known in the power industry. The advances in signal processing and calculation speed within digital relays open up new possibilities for algorithms in the time domain. New protection relay generations will use traveling waves to determine fault and trip accordingly. Testing and verification of correct operation of such devices is a challenging task and mostly not done during commissioning.
Using a novel approach, such tests become possible using conventional protection test devices in the field. This article describes the basic principles of traveling waves, how they are used for fault location and how travelling wave elements can be tested and commissioned.