MEM (22443) LAB Manual Answers Practical No 2

 Practical No.2: Calibration of LVDT Transducer for Displacement Measurement

Practical significance 

LVDT works under the principle of mutual induction the displacement which is nonelectrical energy is converted into electrical energy. LVDT consists of a cylindrical former where it is surrounded by one primary winding in the center of the former and the two secondary windings at the sides. The number of turns in both the Secondary windings is equal, but they are opposite to each other ie, if the len secondary windings are in the clockwise direction, the right secondary windings will be in the anti-clockwise direction, hence the net output voltages will be the difference in voltages between the two secondary coil.

Relevant Program Outcomes (Pos) 

PO1 - Basic knowledge! Apply knowledge of basic mathematics, sciences, and basic Engineering to solve broad-based Mechanical Engineering problems. 

P02- Discipline knowledge Annly mechanical engineering knowledge to solve

broad-used mechanical engineering related problems 

PO3- Experiments and practice: Plan to perform experiments and practices to use

the results to solve h broad-based Mechanical Engineering problems 

PO8 Individual and teamwork: Function effectively as a leader and team member

in diverse multidisciplinary teams.

Competency and Skills 

This practical is expected to develop the following skills for the industry-identified competency 'Use Relevant Analogue and digital measuring devices in Mechanical Engineering related applications 

1. Use LVDT transducer for Displacement measurement

Relevant Course Outcomes

Use relevant instruments for measuring displacement

Practical Outcome 

• Use inductive transducer to measure displacement

Relative Affective Domain. 

•  Practice energy conservation 

• Demonstrate working as a leader or a team member

Minimum Theoretical Background

Differential transformers work on a variable inductance principle and are also used to measure displacement. The most popular variable inductance transducer for linear displacement measurement is the Linear Variable Differential Transformer (LVDT). The LVDT consists of three symmetrically spaced coils would on onto an insulated

bobbin. A magnetic core moves through the bobbin without contact and provides a path for magnetic flux linkage between coils. The position of the magnetic core controls the mutual inductance between the center or primary coil and the two outside of secondary coils. When an AC carrier excitation is applied to the primary coil, voltages are induced in the two secondary coils that are wired in a series-opposing circuit. When the core is centered between the two secondary coils, the voltage induced between the secondary coils is equal but out of phase by 180°. The voltage in the two coils cancels and the output voltage will be zero. When the core is moved from the center position, an imbalance in mutual inductance between the primary coil and the secondary coil occurs and an output voltage develops. The output voltage is a linear function of the core position as long as the motion of the core is within the operating range of the LVDT

Resources Used

S.NO	Name of Resource	Broad Specifications		Quantity	Remarks (If any)
		Make	Details
1	Inductive				Measurement range -0 to 100 mm -Sensorinductive	1
2	transducer

Actual Procedure Followed

Precautions Followed

Observations and Calculations

SN.NO	Actual Micrometer Reading (mm)	Indicator Reading (LVDT)(mm)	Error	% Error
1	1	1.2	0.2 or 0	16.67
2	2	2.3	0.3 or 0.2	13.04
3	3	3.3	0.3 or 0.2	09.09
4	4	4.3	0.3 or 0.1	06.97
5	5	5.3	0.2 or 0	03.8

Error = (Actual Scale Reading- Indicator Scale Reading)

= 1- 1.2

= - 0.2

% Error = (Error/ distance of Step) *100

= (1/ 1.2) × 100

= 16.67

Results

Interpretation of Results

Conclusions

Practical Related Questions 

Note: Below given are a few sample questions for reference. Teachers must design more such questions so as to ensure the achievement of identified CO.

1. Write specifications of LVDT 

ANS:- 

2. List the causes of errors in displacement Measurement

Ans:-

Type of error	Cause of error
Errors generated by the measurement system	Measurement errors arising in the measurement system • Deterioration of measurement accuracy over time (deterioration caused by wear in consumable components)
Errors caused by the user	• Mishandling of the measurement system · Different degrees of skill of the users · User-specific methods of reading the scale
Errors caused by environmental conditions	· Deformation of the measurement target caused by changes in temperature · Measuring in locations with varying brightness levels

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