Why is a deflecting torque being necessary in an indicating instrument?
Deflecting Torque in Indicating Measuring Instruments: The deflecting torque or operating force is required for moving the pointer from its zero position. The system producing the deflecting force is called “Deflecting system or Moving System”.
Which torque is essential for functioning of indicating instruments?
In order to ensure the proper operation of the indicating instruments , the following three torques are required.
- Deflecting (or operating) torque.
- Controlling (or restoring) torque.
- Damping torque.
What is the purpose of deflecting force in an instrument?
When there is no input signal to the instrument, the pointer will be at its zero position. To deflect the pointer from its zero position, a force is necessary which is known as deflecting force. A system which produces the deflecting force is known as a deflecting system.
What are the different types of torque acting in moving system of an indicating instrument?
The different torques acting on the coil of a moving coil…
- Deflecting torque and control torque.
- Deflecting torque and damping torque.
- Control torque and damping torque.
- Deflecting torque, control torque and damping torque.
Why is deflecting required for an electromechanical measuring instrument?
In a measuring instrument, the damping torque is necessary to bring the moving system to rest to indicate steady reflection in a reasonable short time. Under the absence of damping torque the pointer oscillates for a short period of time and comes to steady position and this situation is called under damping.
What is an indicating instrument?
Indicating instruments are those which indicate the magnitude of an electrical quantity at the time when it is being measured. Their indications are given by a pointer moving over calibrated dial. Ammeters, voltmeters are examples of indicating instruments. Energy meter is an integrating type instrument.
What are the essential requirements for indicating instruments?
Basic requirements of indicating instruments are: Balance weight, Control Weight, Pointer, Piston, Scale.
- In essence, an indicating instrument is a moving system that pivots on jewel bearings.
- The following three torques are required to ensure the appropriate operation of the indicating instruments.
How is deflecting torque calculated?
The controlling torque is directly proportional to the angle of deflection of the coil. Control torque Ct =Cθ where, θ = deflection angle in radians and C = spring constant Nm /rad .
What happens when controlling torque equals the deflecting torque?
A control system produces a control torque in proportion to the pointer displacement. These controlling torque will be always in opposition to the deflecting torque. When both torques become equal, the pointer will attain a steady position.
What is deflecting force?
DEFLECTING FORCE The deflecting force is the force required for moving the pointer from rest on the calibrated scale. The current ( or voltage ) under measurement is utilized to produce the deflecting force. There are various effects of current which are utilized for producing deflecting force in the instrument.
What is the deflecting torque?
Deflecting torque: The torque needed to move the pointer over a calibrated scale is known as deflecting torque and it can overcome the inertia of the moving system, controlling torque and damping torque. The deflecting torque in the analog measurement device is proportional to the current through the coil.
What are type of indicating instruments?
How can the damping torque in indicating instruments be provided?
The damping torque in indicating instruments can be provided by: 1 Air friction damping. 2 Fluid friction damping. 3 Eddy current damping. More
What is controlling torque in indicating instruments?
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. The controlling torque in indicating instruments may be provided by one of the following two methods: Spring control. Gravity control.
What is deflecting torque?
In general deflecting torque is nothing but the movement of the pointer in a measuring instrument. There are different types of electrical instruments to measure different types of electrical quantities like current, voltage, power, energy, etc. When we apply the quantity to be measured to the instrument.
How deflecting torque is produced in PMMC instruments?
In PMMC instruments the deflecting torque is produced on the current carrying moving coil when it is placed in the magnetic field produced permanent magnets. The coil tends to move and deflects the pointer attached to it.