There are some advantages of PMMC (permanent magnet moving coil) are given below,
- The PMMC has uniformly divided scale. The scale may be very long, over about 250 degree.
- It has a very high torque to weight ratio.
- The PMMC has consumes low power.
- The PMMC has a very high accuracy.
- The PMMC is free from hysteresis error.
- The PMMC has efficient damping characteristics and is not affected by stray magnetic field.
- Extension of instrument range is possible with the help of shunt and series resistances.
There are some disadvantages of PMMC (permanent magnet moving coil) are given below,
- It has comparatively high cost.
- The PMMC has only suitable for d.c. measurements.
- Aging of permanent magnets and control springs introduces errors.
