There are two methods CR Magnetics uses on the CR5200 designs. 30 Amps and under units are constructed using a standard AC current transformer that is resonated to measure DC current. Above 30 amps range, a hall effect is used. The resonator method enjoys the advantages of AC torroidal transformers: Low leakage, high accuracy and rejection of magnetic influences outside the ring. These minimize the effect the movement within the window causes. Hall effects on the other hand can be influenced by the distance between the magnetic field source and the hall sensor itself. Some of this is alleviated by utilizing a focusing ring that is split to accept the hall effect device. Additionally the full scale range of the device will also have an effect. The higher the range, the less effect wire position has. It is always recommended that with the hall effect device, the wire through the window be as stable as possible.