What is the need of controlling force and damping force in analog measuring instruments?

What is the need of controlling force and damping force in analog measuring instruments?

Due to inertia produced by this system, the pointer oscillates about it final steady position before coming to rest. The time required to take the measurement is more. To damp out the oscillations quickly, a damping force is necessary.

What are the different effects used in producing deflecting torque in an analog instrument?

The deflecting torque is produced by making use of one of the magnetic, heating, chemical, electrostatic and electro-magnetic induction effects of current or voltage and causes the moving system of the instrument to move from its zero position when the instrument is connected in an electrical circuit to measure the …

How is controlling torque provided in Pmmc instruments?

Control – In PMMC instrument the controlling torque is because of the springs. The springs are made up of phosphorous bronze and placed between the two jewel bearings. The spring also provides the path to the lead current to flow in and out of the moving coil.

When the pointer of an indicating instrument is in motion then deflecting torque is opposed by?

Controlling device: The controlling device produces the controlling torque (Tc) which opposes the deflecting torque and increases with the deflection of the moving system. It also brings the pointer back to zero when the deflecting torque is removed.

What is controlling torque and damping torque?

Damping force or Damping Torque: This force is necessary to bring the pointer to rest in its final deflected position quickly. Without such damping, the combination of deflecting torque and controlling torque makes the pointer to oscillate about its final deflected position for some time.

What is deflecting controlling and damping torque?

What is the purpose of controlling torque?

Controlling torque brings the pointer back to zero when the deflecting torque is removed. If it were not provided, the pointer once deflected would not return to zero position on removing the deflecting torque.

How the deflecting torque is produced in electrostatic instrument explain?

The principle of operation of electrostatic instruments is the force of attraction or repulsion between two charged bodies, which leads to the production of deflecting torque. When potential is applied across the plates there exists an electrostatic field and causes a force to exert between the plates.

What is the purpose of damping torque in PMMC meter?

Damping – The damping torque is used for keeping the movement of the coil in rest. This damping torque is induced because of the movement of the aluminium core which is moving between the poles of the permanent magnet.

How is torque used to control an instrument?

The controlling torque is also used to bring the pointer to zero initial position if there is a no deflecting torque. The controlling torque is provided by spring or gravity control. For vertically mounted instrument gravity control is used.

How is deflecting torque related to controlling torque?

For the ammeter to indicate a value of 1 ampere of current a torque or force is required which is called deflecting torque and is proportional to current. The controlling torque is in opposite to the deflecting torque at a point where controlling torque and deflecting torque is equal the pointer stops and show the measured value of the reading.

How is torque controlled on a PMMC scale?

The controlling torque is provided by spring or gravity control. For vertically mounted instrument gravity control is used. Spring is made up of phosphorus bronze to reduce the heating effect. If the control spring have been failed then pointer moves to the maximum position of the scale expect in PMMC.

What are the components of an analog instrument?

All analog electrical indicating instruments require three essential devices, namely, a deflecting or operating device, a controlling device, and a damping device. There is no difference between the basic instrument used to measure current and voltage as both uses a milli ammeter as their basic part.