In moving iron type instrument because of the hysteresis in the iron parts of the moving system the reading is
In moving iron type instrument because of the hysteresis in the iron parts of the moving system the reading is
Right Answer is:
Higher on descending value but lower on ascending values
SOLUTION
Errors in moving iron meters:
Usually, the following errors occur in moving iron meters:
- Friction error
- Temperature error
- Error due to stray magnetic fields
- Hysteresis error
- Frequency error
- Waveform error
Hysteresis error
- Due to the hysteresis effect, error in moving-iron instruments, owing to the magnetic hysteresis effect in the parts of the moving system which are made of iron.
- The magnetism lags behind the current resulting in higher reading when descending values of current or voltage are measured than when ascending values are measured.
- The position of poles in the moving iron changes with rotation. This is known as position error and is usually small.
- The hysteresis error is reduced considerably by making the iron parts small, and reducing the length of paths of working fluxes to the shortest possible, and working of iron at a flux density where hysteresis error is small.