A method is described for eliminating the effects of stray impedance in an a.c. Wheatstone bridge. Whereas the Wagner earthing device uses two auxiliary branches, the modified device uses an auxiliary source of supply. The elimination of the auxiliary impedances is of advantage in a high-voltage bridge.
Brief practical details of the device are given for a 50 c/s Schering bridge. The device is used to study the influence of stray capacities when such a bridge is applied to a transformer manufacture process.