A device for protecting a medium or high voltage electrical network is provided, including a base part connected to means for measuring values representative of the electrical network and to a trip circuit of the electrical network, an active part that includes means for analogue-digital conversion of the values representative of the electrical network and which is mechanically and electrically connected to the base part in a first position referred to as the normal position, and a removable test part that is mechanically and electrically connected to the active part in a second position referred to as the test position. The test part includes means for mechanically and electrically connecting to the base part such that, in the test position, external terminals of the test part are connected to the trip circuit through the base part.