A detector for detecting at least one electric quantity in an electric conductor, the detector comprising: - a frame on which a mechanism unit is fixed, including: - a magnetic toroid, divided into two branches (22A, 22B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the magnetic toroid having a coil wound around at least one of the two branches, - a current sensor, divided into two branches (26A, 26B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the current sensor performing an AC current measurement, - an element transmitting a rotational force to the magnetic toroid and the current sensor, the element being provided with at least one portion able to receive the conductor by bearing, - at least two clamps (30A, 30B) for anchoring the detector on the electric conductor, each clamp being rotatable around an axis (X30A, X30B) parallel to the rotation axis of the branches of the magnetic toroid and defined by the frame, between an open position and a locked position of the clamp, - a base, - at least one electronic device able to send a parameter of the current detected by the current sensor, characterized in that: - the force transmitting element is extended by a trigger, - each anchoring clamp (30A, 30B) has a portion (32A, 32B) in contact with the trigger, - each anchoring clamp bears a member (34A, 34B) protruding in a direction parallel to its axis of rotation, the protruding member being movable with its clamp between the open position and the locked position, - a spring (36A, 36B) is stretched between the protruding member (34A, 34B) and a part (290B, 290B) fixed on the frame, - the spring exerts a rotational torque (C1, C2) on the clamp and tends to move it toward the open position or its locked position as a function of the angular position of the clamp relative to the rotation axis, - between the open position and the locked position, the clamp passes through a neutral position where the protruding member (34A, 34B), its axis of rotation (X30A, X30B) and the fixed part (290A, 290B) are aligned and the spring does not exert a rotational torque on the clamp. - a frame on which a mechanism unit is fixed, including: - a magnetic toroid, divided into two branches (22A, 22B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the magnetic toroid having a coil wound around at least one of the two branches, - a current sensor, divided into two branches (26A, 26B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the current sensor performing an AC current measurement, - an element transmitting a rotational force to the magnetic toroid and the current sensor, the element being provided with at least one portion able to receive the conductor by bearing, - at least two clamps (30A, 30B) for anchoring the detector on the electric conductor, each clamp being rotatable around an axis (X30A, X30B) parallel to the rotation axis of the branches of the magnetic toroid and defined by the frame, between an open position and a locked position of the clamp, - a magnetic toroid, divided into two branches (22A, 22B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the magnetic toroid having a coil wound around at least one of the two branches, - a current sensor, divided into two branches (26A, 26B) rotatable around an axis defined by the frame, between a separated position and a position closed around the electric conductor, the current sensor performing an AC current measurement, - an element transmitting a rotational force to the magnetic toroid and the current sensor, the element being provided with at least one portion able to receive the conductor by bearing, - at least two clamps (30A, 30B) for anchoring the detector on the electric conductor, each clamp being rotatable around an axis (X30A, X30B) parallel to the rotation axis of the branches of the magnetic toroid and defined by the frame, between an open position and a locked position of the clamp, - a base, - at least one electronic device able to send a parameter of the current detected by the current sensor, - the force transmitting element is extended by a trigger, - each anchoring clamp (30A, 30B) has a portion (32A, 32B) in contact with the trigger, - each anchoring clamp bears a member (34A, 34B) protruding in a direction parallel to its axis of rotation, the protruding member being movable with its clamp between the open position and the locked position, - a spring (36A, 36B) is stretched between the protruding member (34A, 34B) and a part (290B, 290B) fixed on the frame, - the spring exerts a rotational torque (C1, C2) on the clamp and tends to move it toward the open position or its locked position as a function of the angular position of the clamp relative to the rotation axis, - between the open position and the locked position, the clamp passes through a neutral position where the protruding member (34A, 34B), its axis of rotation (X30A, X30B) and the fixed part (290A, 290B) are aligned and the spring does not exert a rotational torque on the clamp.