Electrical protection unit including a current limiter device

An electrical protection unit A including a main conductor and, for each main conductor, a current limiter device connected in series with the main conductor to limit the current when a current or temperature threshold is exceeded, the limiter device including an element made of a material having a positive temperature coefficient, called PTC, and being capable of controlling a device for tripping the mechanism M for opening the contacts of the protection unit D, to cause the opening of the contacts of the unit when the threshold is exceeded leading to a change of state of the element between a low resistance state and a high resistance state. The PTC element includes the trip device, in such a way that this element itself provides the functions of fault current limitation and of tripping the mechanism for opening the contacts.