Errors in Moving Iron Instruments There are two types of error which occur in moving iron instruments. They are 1. Errors with both A.C and D.C work: (a) Hysteresis error (b) Stray magnetic field error. (c) Temperature error. (d) Friction error. 2. Errors with A.C work only: (a) Frequency error. (b) Error due to reactance of the instrument coil. (c) Error due to eddy current. ...