Device for detecting an electric arc, comprising: • means for measuring (1, 4) an AC electric current and an AC voltage, • analysis means that are connected to the measurement means (1, 4), and comprising • calculation means for calculating, at the cadence of a sequencing signal (Seq), an integral of an absolute value: • of the AC electric current over at least one half-cycle, and delivering a current integration signal (Si(t)); • of the AC voltage over at least one half-cycle, and delivering a voltage integration signal (Su(t)), • differentiation means (DIFF) delivering • a current differentiation signal (dSi(t)), representative of the difference between a first current integration signal (Si(t)) and a second current integration signal (Si(t-T)) that is measured over a period before said first integration signal; • a voltage differentiation signal (dSu(t)), representative of the difference between a first voltage integration signal (Su(t)) and a second voltage integration signal (Su(t-T)) that is measured over a period before said first integration signal, • decision means that are connected to the analysis means and which are intended to send at least one trip signal (Trip), the decision means comprising detection means (DETECT 1, DETECT 2, DETECT 3, DETECT 4,..., DETECT k) that are each intended to deliver at least one signal for aiding the decision (N1, N2, N3,..., Nk), and comprising a decision unit (DECIDE) that is intended to deliver at least one trip signal (Trip), characterized in that the decision means comprise an inhibitor unit (INHIBIT) delivering adaptive inhibition signals (Frzi1, Frzi2, Frzi3,..., Frzin) to the detection means (DETECT 1, DETECT 2, DETECT 3, DETECT 4,..., DETECT k), • said at least one signal for aiding the decision (N1, N2, N3,..., Nk) being dependent on at least one adaptive inhibition signal (Frzi1, Frzi2, Frzi3,..., Frzin), and on the current differentiation signal (dSi(t)) or on the current integration signal (Si(t)); • said at least one trip signal (Trip) being dependent on the value of signals for aiding the decision (N1, N2, N3,..., Nk). • means for measuring (1, 4) an AC electric current and an AC voltage, • analysis means that are connected to the measurement means (1, 4), and comprising • calculation means for calculating, at the cadence of a sequencing signal (Seq), an integral of an absolute value: • of the AC electric current over at least one half-cycle, and delivering a current integration signal (Si(t)); • of the AC voltage over at least one half-cycle, and delivering a voltage integration signal (Su(t)), • differentiation means (DIFF) delivering • a current differentiation signal (dSi(t)), representative of the difference between a first current integration signal (Si(t)) and a second current integration signal (Si(t-T)) that is measured over a period before said first integration signal; • a voltage differentiation signal (dSu(t)), representative of the difference between a first voltage integration signal (Su(t)) and a second voltage integration signal (Su(t-T)) that is measured over a period before said first integration signal, • calculation means for calculating, at the cadence of a sequencing signal (Seq), an integral of an absolute value: • of the AC electric current over at least one half-cycle, and delivering a current integration signal (Si(t)); • of the AC voltage over at least one half-cycle, and delivering a voltage integration signal (Su(t)), • of the AC electric current over at least one half-cycle, and delivering a current integration signal (Si(t)); • of the AC voltage over at least one half-cycle, and delivering a voltage integration signal (Su(t)), • differentiation means (DIFF) delivering • a current differentiation signal (dSi(t)), representative of the difference between a first current integration signal (Si(t)) and a second current integration signal (Si(t-T)) that is measured over a period before said first integration signal; • a voltage differentiation signal (dSu(t)), representative of the difference between a first voltage integration signal (Su(t)) and a second voltage integration signal (Su(t-T)) that is measured over a period before said first integration signal, • a current differentiation signal (dSi(t)), representative of the difference between a first current integration signal (Si(t)) and a second current integration signal (Si(t-T)) that is measured over a period before said first integration signal; • a voltage differentiation signal (dSu(t)), representative of the difference between a first voltage integration signal (Su(t)) and a second voltage integration signal (Su(t-T)) that is measured over a period before said first integration signal, • decision means that are connected to the analysis means and which are intended to send at least one trip signal (Trip), the decision means comprising detection means (DETECT 1, DETECT 2, DETECT 3, DETECT 4,..., DETECT k) that are each intended to deliver at least one signal for aiding the decision (N1, N2, N3,..., Nk), and comprising a decision unit (DECIDE) that is intended to deliver at least one trip signal (Trip), • said at least one signal for aiding the decision (N1, N2, N3,..., Nk) being dependent on at least one adaptive inhibition signal (Frzi1, Frzi2, Frzi3,..., Frzin), and on the current differentiation signal (dSi(t)) or on the current integration signal (Si(t)); • said at least one trip signal (Trip) being dependent on the value of signals for aiding the decision (N1, N2, N3,..., Nk).