Instrumentation and Measurement (P-01)

 

Instrumentation and Measurement 

What is measurement system?

System of measurement refers to the process of associating numbers with physical quantities and phenomena. It is more like a collection of units of measurement and rules relating them to each other.

What is measurement system architecture?

A system architecture is the conceptual model that defines the structure behaviors and more views of a system.

Briefly explain measurement system architecture with diagram?

A system architecture is the conceptual model that defines the structure behaviors and more views of the system.

Step-1: Inputs variable should be in certain amount of measured quantity.

Step-2: The main function of the primary sensing element is to sense the input variable and gives the output according to the measurand.

Step-3: It receives the output of the primary sensing element as input. The conversion of the variable from one form to another form takes place.

Step-4: This element manipulates the input variable. This is done for the required output from the input variable.

Step-5: Transmission of data from one element to another element takes place in this data transmission element.

Step-6: Data modified and processed before final result comes. Data processing element modifies the data for some reasons like,

·        Modification for final output form.

·        Modification for some final calculation.

·        Modification for errors in the instruments such as signal errors, temperature errors, etc.

Step-7: Finally, data is present to the observer via the data presentation element. The presentation element is such as to monitor, recorders, needle pointers, LCD and LED display, alarms, indicators like the analog indicator and digital indicator, etc.

Step-8: The measurement data is finally delivered to the observer via the data presentation element, for further clarification and calculation.

 

What is overview of signal conditioning?

Signal conditioning is an electronic circuit that manipulates a signal in a way that prepares it for the next stage of processing Signal conditioning is of the fundamental building blocks of modern data acquisition.

Difference between active and passive instrument?

Active instrument	Passive instrument
Active instruments are those where the quantity is measured with the help of external power.	Whereas no external power required to measure a quantity is passive instrument.
Additional external energy input source is required.	Additional external energy input source not required.
The resolution is high.	The resolution is less
Complicated to design.	Simple to design.
Example are liquid level indicator, flow indicator.	Example are pressure gauge, voltmeter, ammeter.

What is hysteresis effect? Explain.

Hysteresis occurs in a system that involves a magnetic field. Hysteresis is the common property of ferromagnetic substance. When the magnetization of ferromagnetic materials lags behind the magnetic field this effect can be described as the hysteresis effect.

Explain: When a ferromagnetic substance is placed inside a current carrying coil. Due to the magnetic field that is present the substance gets magnetized. If we revers the direction of the current then the substance gets demagnetized this process is known as hysteresis.

 

 

 

Explain of the hysteresis loop?

The hysteresis loop is explained below.

·        The magnetic flux density (B) is increased when the magnetic field strength (H) is increased from zero.

·        With increasing the magnetic field there is an increase in the value of magnetism and reaches point (A) which is called saturation point where (B) is constant.

·        With a decrease in the value of the magnetic field there is a decrease in the value of magnetism. But at (B) and (H) are equal to zero, substance retains some amount of magnetism is called retentivity.

·        When there is decrease in the magnetic field toward the negative side magnetism also decrease. At the point (C) the substance is completely demagnetized.

·        The force required to remove the retentivity of the material is known as coercive force (C).

·        In the opposite direction the cycle is continued where the saturation point is (D), retentivity point is (E) and coercive force is (F).

·        Due to the forward and opposite direction process the cycle is complete and is cycle is called the hysteresis loop.

What is Wheatstone Bridge?

Wheatstone bridge also known as the resistance bridge, calculates the unknown resistance by balancing two legs of the bridge circuit. One leg includes the component of unknown resistance.

Derive the equation to calculate unknown resistance using Wheatstone bridge?

The current enters the galvanometer and divides into two equal magnitude current as I₁ and I₂. The following condition exists when the current through a galvanometer is zero.

I₁P = I₂R ……… (1)

The current in the bridge in a balanced condition, we can write

I₁=I₃=

I₂=I₄=

Putting the value of I₁ and I₂ in equation (1), we get

 

 

Equation (2) shows the balanced condition of the bridge, while (3) determines the value of the unknown resistance.

Here,

·        R is the unknown resistance.

·        S is the standard arm of the bridge.

·        P and Q is the ratio of the arm of the bridge.

 

 

Drive the equation force of electromagnetic?

Magnetism is the force that moving charges exert on one another. This formal definition is based on this simple equation

FB = qv × B

The combination of electric and magnetic forces on a charged object is known as the “Lorentz force”

F = q (E + v × B)

For large amount of charge

FB = qv × B