Explanation of Errors in Moving Coil Instruments
Errors in Moving Coil Instruments The errors that usually occur in PMMC instruments are 1. The frictional error. 2. Temperature error. 3. The error owing weakening of permanent magnet. 4. Stray magnetic field error. 5. Thermo-electric error. 6. Observational error. 1. The frictional Error: The friction of the pivot in the jewel produces a frictional torque which affects the instrument reading. This error is more serious for sensitive instruments designed for low operating torque. Remedy: The frictional error in PMMC instruments can be produced by providing proper pivoting and balancing i.e. these errors may be reduced by adopting a moving system of light construction and large deflecting torque. 2. ...