A method and an array for measuring a primary current in a primary conductor that is magnetically coupled to a secondary conductor via a ferromagnetic core. In said method, a voltage having a specific amplitude is applied to the secondary conductor such that a secondary current flows for reversing the magnetization of the ferromagnetic core; the secondary current is measured while the magnetization of the ferromagnetic core is reversed in order to obtain a first measured value; the polarity of the voltage is reversed such that a secondary current flows for once again reversing the magnetization of the ferromagnetic core; the secondary current is measured while the magnetization of the core is reversed in order to obtain a second measured value; the primary current is calculated in accordance with the first and the second measured value, the polarity of the voltage being regularly reversed at a certain sensor frequency that is continuously varied.