A repulsion type ammeter when used on A.C circuit reads
Right Answer is:
R.M.S value of the current
A repulsion type ammeter when used on the A.C circuit reads the R.M.S value of the current.
Moving iron instruments are used to measure current and voltage. They are made as ammeters and voltmeters and can measure both ac and dc currents and voltages respectively. Two types of moving iron instruments are manufactured. One type is called the attraction type and the other type is called the repulsion type.
Repulsion type Ammeter
- In the repulsion type, a fixed vane or rod is also used.
- Controlling torque is provided by spring or weight (gravity).
- Damping torque is normally pneumatic, the damping device consisting of an air chamber and a moving vane attached to the instrument spindle.
Moving iron instruments have their deflection is proportional to the square of the current flowing through the coil. These instruments are thus said to follow a square-law response (R.M.S Value) and have non-uniform scale marking.
Deflection being proportional to the square of the current, whatever be the polarity of the current in the coil, deflection of a moving iron instrument is in the same direction. Hence, moving iron instruments can be used for both DC and AC measurements.