This paper reports real tests results that were obtained with a commercial IED that already works using the Process Bus, to verify the performance.
Firstly the IED was tested by using just one MU (Merging Unit) providing samples of Currents and Voltages to the IED through the LAN (Local Area Network). These samples were used by IED to measure the line impedance in order to decide about to trip or not. After exhaustive tests made with this arrangement the number of Merging Units connected to the LAN was increased, and the tests were repeated to investigate the effects of the loading to the system behavior (Up 10 MU ́s was connected together). The faults were carried on using a relay test set, and the trip time was measured for each case condition.
To evaluate the Process Bus behavior it were realized more than one thousand faults. The LAN was gradually loaded by increasing the number of MU connected to it. It will be evaluated if the trip time was affected with the increase in number of merging units.
