Why is Dynamometer type wattmeter is equipped with mirror type scales ...
Construction of Electrodynamometer Wattmeter:
Fixed Coils:
- The reason for using fixed coils as current coils is that they can be made more massive and can be easily constructed to carry considerable current since they present no problem of leading the current in or out.
- The fixed coils are wound with heavy wire. This wire is stranded or laminated especially when carrying heavy currents in order to avoid eddy current losses in conductors.
Moving Coil:
- The moving coil is mounted on a pivoted spindle and is entirely embraced by the fixed spindle & is entirely embraced b the fixed current coils.
- The use of moving coil as pressure coil is a natural consequence of design requirements.
Scales and Pointers:
- They are equipped with mirror type scales and knife-edge pointers to remove reading errors due to parallax.
Damping:
- The damping is the effect which reduces the movement of the pointer.
- In this Wattmeter Air friction damping is used.
- The other types of damping are not used in the system because they destroy the useful magnetic flux.

View all questions of this testWhy is Dynamometer type wattmeter is equipped with mirror type scales ...
Construction of Electrodynamometer Wattmeter:
Fixed Coils:
- The reason for using fixed coils as current coils is that they can be made more massive and can be easily constructed to carry considerable current since they present no problem of leading the current in or out.
- The fixed coils are wound with heavy wire. This wire is stranded or laminated especially when carrying heavy currents in order to avoid eddy current losses in conductors.
Moving Coil:
- The moving coil is mounted on a pivoted spindle and is entirely embraced by the fixed spindle & is entirely embraced b the fixed current coils.
- The use of moving coil as pressure coil is a natural consequence of design requirements.
Scales and Pointers:
- They are equipped with mirror type scales and knife-edge pointers to remove reading errors due to parallax.
Damping:
- The damping is the effect which reduces the movement of the pointer.
- In this Wattmeter Air friction damping is used.
- The other types of damping are not used in the system because they destroy the useful magnetic flux.
