The CR-50, CR-100 and CR-250 units include specially designed current generation systems that can check the current / time trigger curve of automatic switches and indirect protection relays. Its operation principle is based on the injection of an alternating current that can be adjusted throughout the circuit being tested with a short-circuit cable loop. The connection of an auxiliary contact of the switch being tested can be used to measure the trip time for each current selected. The test is easily carried out with a start-stop control. An automatic meter is responsible for taking the measurements and showing them on the display. We can highlight that the unit can be used to check the full protection system, including the current transformer in the case of indirect relays, since the current can be injected on the primary side of these transformers. After the test, a digital display automatically shows the value of the current injected and the trip time until the RESET button is pressed.