Damping Torque Essay

Various Operating Force:- DEFLECTING TORQUE:

The deflecting torque is produced by utilize the various effects (magnetic effect, induction effect, thermal effect, hall effect) of electric current or voltage, and causes the moving system and hence the pointer to move from zero position.

CONTROLLING TORQUE:

Controlling torque controls the deflection and tries to stop the pointer at its position.

But due to inertia, the pointer oscillates in the region of its final position before coming to rest. Hence damping torque is providing to keep away (avoid) from this oscillation and bring the pointer quickly to its final position.

The value of controlling torque depends on the mechanical design of the control devices. For spiral springs and strip

consists of a light aluminium piston which moves in a quadrant shaped air chamber which is closed ae one end. The clearance between chamber wall and piston is uniform and very small. Thepiston is mounted on the spindle of the moving system. Now, with the motion, the piston displaces air and thereby a damping force is created on the piston that produces a torque on the spindle. When the movement is quick the damping force is greater, when the spindle is at rest, the damping force is zero. When the piston moves out of chamber, pressure in the closed space falls, and the pressure in the open side of piston is high then on the other side. Thus there is again an opposition to movement.

FLUID FRICTION DAMPING:

This form is damping is similar to air friction damping. So the action is the same as in the air friction damping. Oil is used in place of air and as the viscosity of oil is greater than the air, the damping force is also much greater. The piston attached to the spindle is arranged to move in the damping oil. When the moving system is moves, the disc is moves in oil so the friction drag is produced, this friction drag always oppose the motion.

In Arrangement show in the figure the numbers of piston are attached to the spindle, these pistons are submerged in oil and moves in it on vertical plane. This arrangement gives a greater

Depending upon the simple phenomenon attraction type moving iron instrument was developing. Whenever two piece of iron are kept side by side and magnet is brought nearer to them the iron pieces will repulse each other. So this repulsion force is due to same magnetic pole induced in same sides the iron pieces due external magnetic field. These repulsion forces increase if field strength of the magnet is increased. Like case if magnet is electromagnet, then the magnetic field strength can easily controlled by controlling input current to the magnet. Hence if the current increases so the repulsion force between the pieces of iron is increased and the current decreases so the repulsion force between them is decreased. Depending upon this type of phenomenon the repulsion type moving iron instrument was