Which type of damping is generally preferred in case of instruments having a weak magnetic field?
Right Answer is:
Air friction damping
Air Friction Damping
- In this system, a light aluminum piston is attached to the spindle of the instrument and is arranged to move in a fixed air chamber closed at one end.
- The cross-section of the chamber may be either circular or rectangular and the clearance between the piston and the side of the chamber is small and uniform.
- The compression and suction action of the piston on the air in the chamber damp the possible oscillations of the moving system because the motion of the piston in either direction is opposed by the air.
- It is used when the operating field is weak as used in moving the iron and electro-dynamometer type instrument.
Eddy Current Damping: It is used in a strong operating field. e.g., PMMC (Permanent Magnet Moving Coil instrument) type.
Fluid Friction Damping: Used in high voltage measurement. Used in the vertically mounted instrument. e.g., Electrostatic type instrument.