A testing apparatus for imposing a traveling wave signal on an electric system signal for testing a fault detector is disclosed herein. The fault detector may be configured to simulate a fault at a particular location by controlling the timing of the traveling wave signal. The testing apparatus may be configured to impose multiple traveling wave signals to test the accuracy of the fault location determined by the fault detector. The testing apparatus may be configured to determine the calculation accuracy of the fault detector. The testing apparatus may impose a traveling wave signal on a signal simulating an electrical signal on an electric power delivery system. The testing apparatus may be used to test capabilities of a fault detector of detecting a fault using traveling waves or incremental quantities.