A current sensor system (100; 300; 450; 550) for measuring an AC electrical current having frequencies in a predefined frequency range, the current sensor system comprising: - an electrical conductor portion (101; 301) extending in a first direction and configured for conducting said AC electrical current, thereby creating a first magnetic field; - a U-shaped magnetic shielding (140; 340) partially surrounding said electrical conductor portion, and having a central shielding portion (143; 343) extending in a second direction perpendicular to the first direction, and having two shielding leg portions (141, 142; 241, 242; 341; 342) extending in a third direction perpendicular to the first and second direction (X, Y); - a metal plate or a metal layer (103; 303; 403; 503) arranged at a predefined distance (g) from the shielding legs portions for allowing eddy currents to flow in said metal plate or metal layer, thereby creating a second magnetic field which is superimposed with the first magnetic field; - a magnetic sensor device (102; 202; 302) arranged between the conductor portion (101; 301) and the metal plate or metal layer, and arranged between the two shielding leg portions (141, 142; 241, 242; 341; 342), and configured for measuring a magnetic field component (Bx) oriented in the second direction; characterised in that the metal plate or metal layer has a length (Lp) larger than a length (Lsh) of the shielding measured in the first direction, and has a width (Wp) larger than 90% of a distance (Wsi) measured in the second direction between the inner sides of the shielding leg portions, and has a thickness (Tp); or the metal plate or metal layer is a portion of a metal housing with a cavity in the vicinity of the magnetic sensor, the metal plate or metal layer having a residual thickness (Tres) in the vicinity of the magnetic sensor. - an electrical conductor portion (101; 301) extending in a first direction and configured for conducting said AC electrical current, thereby creating a first magnetic field; - a U-shaped magnetic shielding (140; 340) partially surrounding said electrical conductor portion, and having a central shielding portion (143; 343) extending in a second direction perpendicular to the first direction, and having two shielding leg portions (141, 142; 241, 242; 341; 342) extending in a third direction perpendicular to the first and second direction (X, Y); - a metal plate or a metal layer (103; 303; 403; 503) arranged at a predefined distance (g) from the shielding legs portions for allowing eddy currents to flow in said metal plate or metal layer, thereby creating a second magnetic field which is superimposed with the first magnetic field; - a magnetic sensor device (102; 202; 302) arranged between the conductor portion (101; 301) and the metal plate or metal layer, and arranged between the two shielding leg portions (141, 142; 241, 242; 341; 342), and configured for measuring a magnetic field component (Bx) oriented in the second direction; the metal plate or metal layer has a length (Lp) larger than a length (Lsh) of the shielding measured in the first direction, and has a width (Wp) larger than 90% of a distance (Wsi) measured in the second direction between the inner sides of the shielding leg portions, and has a thickness (Tp); or the metal plate or metal layer is a portion of a metal housing with a cavity in the vicinity of the magnetic sensor, the metal plate or metal layer having a residual thickness (Tres) in the vicinity of the magnetic sensor.