➢ Constructional details of dynamometer type wattmeter:-
• Fixed Coils [F1 & F2]. : fixed coil is divided into two sections to give a uniform field near the center [F1 & F2]. The operating field is produced by the fixed coil
• Moving coil [M]:-The moving system consists of a coil mounted on the spindle which is free to rotate in the space between the two fixed coils. The coil is made up of thin copper wire and is air cored to avoid hysteresis.
• Control torque provided by two spiral springs. They also act as connecting leads for the moving coil. Pointer is mounted on the spindle.
• Mirror is provided to avoid parallax error.
• Damping is provided by air friction damping