A measuring sensor, a measuring device, a detection module, a measuring method and a calibration method are disclosed. In an embodiment a measuring sensor includes at least one inductive current transformer configured to generate an electrical measurement signal dependent on a current flow in a conductor passing through the inductive current transformer, a terminal configured to connect the inductive current transformer to a measuring transducer, wherein the inductive current transformer is electrically connected to at least two terminal contacts of the terminal in order to transmit the electrical measuring signal to the measuring transducer and a detection module connected between the inductive current transformer and the two terminal contacts, wherein the detection module is configured to return a response signal when a retrieval signal is applied to the two terminal contacts.