A Rogowski coil current sensor (16; 216; 416; 516) for measuring a current flowing in an electrical conductor, the current sensor comprising: - a main winding (22; 222; 422; 522) comprising two ends (42, 44; 242, 244; 442, 444; 542, 544), - a closing mechanism (20; 220; 420; 520) adapted to connect one end (42; 242; 442; 542) of the main winding to the other end (44; 244; 444; 544), the closing mechanism being movable relative to one of the ends (44; 244; 444; 544) between a closed position and an open position, wherein the main winding (22; 222; 422; 522) and the closing mechanism (20; 220; 420; 520) form a closed loop around the electrical conductor and an open loop respectively, the two ends (42, 44; 242, 244; 442, 444; 542, 544) being, in the closed position of the closing mechanism, arranged along a longitudinal axis of the closing mechanism (20; 220; 420; 520) and spaced apart from each other along the longitudinal axis, and - a secondary winding (32; 232; 432; 532) arranged between the ends (42, 44; 242, 244; 442, 444; 542, 544) of the main winding (22; 222; 422; 522), in the closed position of the closing mechanism (20; 220; 420; 520), the secondary winding (32; 232; 432; 532) comprising a plurality of turns offset from each other along the longitudinal axis, the diameter of the turns of the secondary winding (32; 232; 432; 532) being greater than or equal to the diameter of the turns of the main winding (22; 222; 422; 522), characterised in that, in the closed position of the closing mechanism (20; 220), the distance measured along the longitudinal axis between each end and the secondary winding (32; 232; 432; 532) is less than 1.5 mm, and in that the secondary winding (432; 532) comprises, along the longitudinal axis, a central portion (432A; 532A) and first (432B; 532B) and second (432C; 532C) distal portions, and in that at least one of the distal portions (432B, 432C; 532B, 532C) comprises a greater number of turns per unit of length than the number of turns per unit of length of the central portion (432A; 532A), the distance measured along the longitudinal axis X between one end of the main winding and one end of the secondary winding being greater than 1 mm, and the distance measured along the longitudinal axis X between the other end of the main winding and the other end of the secondary winding being greater than 1 mm. - a main winding (22; 222; 422; 522) comprising two ends (42, 44; 242, 244; 442, 444; 542, 544), - a closing mechanism (20; 220; 420; 520) adapted to connect one end (42; 242; 442; 542) of the main winding to the other end (44; 244; 444; 544), the closing mechanism being movable relative to one of the ends (44; 244; 444; 544) between a closed position and an open position, wherein the main winding (22; 222; 422; 522) and the closing mechanism (20; 220; 420; 520) form a closed loop around the electrical conductor and an open loop respectively, the two ends (42, 44; 242, 244; 442, 444; 542, 544) being, in the closed position of the closing mechanism, arranged along a longitudinal axis of the closing mechanism (20; 220; 420; 520) and spaced apart from each other along the longitudinal axis, and - a secondary winding (32; 232; 432; 532) arranged between the ends (42, 44; 242, 244; 442, 444; 542, 544) of the main winding (22; 222; 422; 522), in the closed position of the closing mechanism (20; 220; 420; 520), the secondary winding (32; 232; 432; 532) comprising a plurality of turns offset from each other along the longitudinal axis, the diameter of the turns of the secondary winding (32; 232; 432; 532) being greater than or equal to the diameter of the turns of the main winding (22; 222; 422; 522), characterised in that, in the closed position of the closing mechanism (20; 220), the distance measured along the longitudinal axis between each end and the secondary winding (32; 232; 432; 532) is less than 1.5 mm, and in that the secondary winding (432; 532) comprises, along the longitudinal axis, a central portion (432A; 532A) and first (432B; 532B) and second (432C; 532C) distal portions, and in that at least one of the distal portions (432B, 432C; 532B, 532C) comprises a greater number of turns per unit of length than the number of turns per unit of length of the central portion (432A; 532A), the distance measured along the longitudinal axis X between one end of the main winding and one end of the secondary winding being greater than 1 mm, and the distance measured along the longitudinal axis X between the other end of the main winding and the other end of the secondary winding being greater than 1 mm.