A Zero-Flux-Transducer consists of a measuring head and an electronic module. In the measuring head there are three iron cores with a common secondary winding but with separate auxiliary windings The primary current lp, via the winding Lp, produces a magnetic field in the three iron cores of the transducer. Thereby Lp mostly consists of the primary conductor, which is lead through the transducer. At very low primary currents, more windings can be applied on the primary side. The compensation current lc compensates the magnetic field of the primary current and provides a steady zero-flux in the iron core. This compensation current is driven by an operation amplifier to which both inputs a signal is connected which is proportional with the AC- and DC-component of the primary conductor current. The AC-component is thus induced into the auxiliary winding Lh1. The DC-component and the very low-frequency component comes from the so-called Zero-Flux-Detector (symmetry detector). Via an oscillator and the auxiliary windings Lh2 and Lh3, the other two iron cores are driven into saturation in different directions. Both iron cores and the auxiliary windings Lh2 and Lh3 are built identically. The currents via Lh2 and Lh3 are thus identical. In this case the main core flux is zero. A direct current via the primary conductor results in a flux via the core. Therefore both Zero-Flux-Detector cores can no longer be driven into saturation identically, and the two currents via Lh2 and Lh3 are no longer equal. The difference between the currents is proportional with DC component of the current lp. The Zero-Flux-Detector processes this signal and leads it to the DC-input of the operation amplifier which drives the compensation current. This way the DC-component of the primary current can also be compensated. The compensation current is an accurate reproduction of the primary current, and can be evaluated as a galvanic separated signal by all types of measuring instruments. The burden resistor is only be used if the measuring instrument only has voltage inputs. This is always the case for oscilloscopes and data acquisition systems. The advantage of this technology is mostly the high accuracy of the transducer. The sensitivity of the Zero-Flux-Detector and of the iron cores allows the best possible ppm-accuracy. The bandwidth is mainly influenced by the transmission condition of the main core, the capacity of the windings Lh1 and Lc and the frequency operation of the operation amplifier and burden resistor. A few hundred kHz can easily be obtained.