It is difficult to properly evaluate the electromagnetic disturbances generated by large fixed installations because of, i.e., the background noise, unsteady emissions and transient interferences. Those challenging EMC issues have been recently studied in European research projects on improved test methods in industrial environments. In order to overcome traditional in-situ EMI measurement troubles, a novel time-domain methodology is proposed and used in a real fixed installation with large machinery. Firstly, a comparison between the developed measurement system, using an oscilloscope, and an EMI receiver is done in some test-cases for validation purposes. After verifying the accuracy of the measurements, we proceed with the measurement campaign applying the full time-domain methodology. The main benefits of employing the time-domain system are emphasised through the results. It was observed that the some remarkable advantages of the time-domain approach are: triggering by disturbance events, extremely reduce the capturing time, identify on real time the worst emissions modes of the EUT, avoid changes at the background noise and perform simultaneous multichannel synchronous measurements.