where G is a constant independent of flux density, the area of the moving coil, and the number of turns.
The opposing torque Tc is generated by a spring, which is proportional to the deflection angle θ:
Tc=Kθ Equ(2)
where K is the spring constant, dependent on the spring’s material and dimensions.
Under balanced conditions:
Td=Tc Equ(3)
Substituting Td and Tc into Equation (3):
GI = KθI = (K/G)θ
The measured current thus depends on the deflection angle θ and the meter constants G and K. Current values are directly read from the deflection angle θ, which is calibrated using G and K.
Disadvantages of Deflection-Type Instruments
- Low Accuracy: These instruments exhibit relatively low measurement accuracy.
- Reduced Sensitivity: Sensitivity is lower compared to null-type instruments.
- Calibration Dependency: Measurement accuracy relies on the instrument’s calibration.
