is that there are two fixed coils (C1 and C2) placed on left- and right-hand side of the armature. Each coil consists of a few turns of thick copper wire connected in series with the supply. These two coils are connected to the main supply in the circuit. The electromagnetic field is produced in these two coils. Thisis proportional to the current to be measured. The armature rotates with the help of this electromagnetic field. The armature coils produce current in it and provides this current on its commutator. This current is proportional to the. The operating torque is produced due to the reaction of electromagnetic field and the armature coils. Braking torque is produced due to the eddy currents produced in a disc which is fixed on a spindle of the same armature between the two brake magnets (permanent magnets). When the speed of the disc reached on its steady position then the braking torque and operating torque becomes equal to each other and the revolution of the disc is proportional to