1) Electrodynamometer wattmeter is used for measurement of power.

2) The figure shows construction of electrodynamometer wattmeter.

3) It consists of fixed coil, moving coil, damping element, control element, pointer and scale.

4) FIXED COIL:-

1. The fixed coils carry current of the circuit.
2. They are divided into two halves.
3. They are air cored and wound with heavy wire. This wire is stranded or laminated especially when carrying losses in conductors.
4. The fixed coils of earlier wattmeter were designed to carry a current of 100A but modern design usually limits the maximum current to 20A.

5) MOVING COIL:-

1. The moving coil is mounted on a pivoted spindle and is entirely embraced by the fixed current coils. It is air cored.
2. The spring control is used for the movement of coil.

6) DAMPING ELEMENT:-

The light aluminum vane carried by moving system acts as damping element. It moves in a sector shaped box and provides air fiction damping.

7) CONTROL SYSTEM:-

Spring control is used for this instrument.

8) Scales and pointers:-

They are equipped with mirror type scales and knife edge pointers to remove reading errors due to parallax.