ee38 measurments & instrumentation lab

8/10/2019 EE38 Measurments & Instrumentation Lab

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EINSTEINCOLLEGE OF ENGINEERING

Sir.C.V.Raman Nagar, Tirunelveli-12

Department of Electrical & Electronics

Engineering

Subject Code: EE 38

Measurements & Instrumentation Lab

Name :

Reg No :

Branch :

Year & Semester :


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Einstein College of Engineering

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TABLE OF CONTENTS

S.No Date Name of the Experiment

Page

No.

Marks

Staff

Initial

Remarks

1 DC Bridge Wheatstones Bridge

2

DC Bridge Kelvins double

Bridge

3

AC Bridge Maxwells Inductance-

Capacitance Bridge

4 AC Bridge Scherings Bridge

5 Study of transients

6

Study of Displacement Transducer -

LVDT

7 Instrumentation Amplifier

8

Calibration of Single Phase Energy

Meter

9 Calibration of Current Transformer

10 Digital to Analog Converter

11 Study of Pressure Transducer

12

Measurement of Three Phase Power

and Power Factor

13Measurement of Iron Loss

(Maxwell Bridge)


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CIRCUIT DIAGRAM:


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Ex. No: DC BRIDGE WHEATSTONES BRIDGE

Date:

AIM:

To measure the given medium value of resistance using Wheatstones Bridge

APPARATUS REQUIRED:

S.No Apparatus Range Quantity

1 Resistors 1K 22 Unknown resistors

3 Decade Resistance Box - 1

4 Regulated Power Supply (0-30V) 1

5 Galvanometer - 1

6 Bread board - 1

7 Connecting wires - 1 set

DESIGN:


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TABULATION:

S.No

Known Resistances (K)True Value

(K)

Measured

Value

(K)

P Q S

MODEL CALCULATION:


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FORMULA USED:R = S * (P/Q)

Where R Unknown resistance in

S, P, Q known resistances in

THEORY:

Wheatstone bridge is used to measure an unknown electrical resistance by

balancing two legs of a bridge circuit, one leg of which includes the unknown

component. Its operation is similar to the potentiometer.

In the circuit on the left, Ris the unknown resistance to be measured; P, Q

and S are resistors of known resistance and the resistance of S is adjustable. If the

ratio of the two resistances in the known leg (P/Q) is equal to the ratio of the two in

the unknown leg (R/S), then the voltage between the two midpoints (b and d) will bezero and no current will flow through the ammeter. S is varied until this condition is

reached. The direction of the current indicates whether S is too high or too low.

Detecting zero current can be done to extremely high accuracy. Therefore, if P, S and

Q are known to high precision, then Rcan be measured to high precision. Very small

changes in Rdisrupt the balance and are readily detected. At the point of balance, theratio of R/S = P/Q.

PROCEDURE:

1. Connections are made as per the circuit diagram.

2. Set 12v in the RPS

3. The variable resistance is varied until the galvanometer (or) ammeter shows

the zero deflection.

4. The unknown resistance is calculated using the formula R = S * (P/Q)


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DISCUSSION QUESTIONS:

1. What is meant by bridge circuit?

2. What are the uses of bridge circuits?

3. What are the advantages of bridge circuits?

4. What are the two main types of bridges?

5. What is meant by DC Bridge?

6. What are the types of DC bridges?

7. What is Wheatstone bridge?


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8. Write the balancing equation for Wheatstone bridge.

9. State the advantages & disadvantages of Wheatstone bridge method. Advantages:

Disadvantages:

10. What are the applications and limitations of Wheatstone bridge?

RESULT:


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CIRCUIT DIAGRAM:


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AIM:To measure the given low value of resistance using Kelvins double bridge

method

APPARATUS REQUIRED:


1 Resistors 1,100 2 each2 Unknown resistors

3 Decade Resistance Box - 1

4 Regulated Power Supply (0-30V) 1

5 Galvanometer - 16 Bread board - 1

7 Connecting wires - 1 set

DESIGN:

Ex. No: DC BRIDGE KELVINS DOUBLE BRIDGE

Date:


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TABULATION:

S.No

Known Resistances ()True Value

()

Measured

Value

()P Q p q S R x

MODEL CALCULATION:


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FORMULA USED:

L

K

Q

P

rLK

Lr

Q

PSR

Where, Rx Unknown resistance in

P, Q, p, q Known resistances in S Variable resistance

THEORY:

A Kelvin bridge is used to measure an unknown electrical resistance below

1. Its operation is similar to the Wheatstones bridge except that in the circuit arenot four but seven resistors. When using a Wheatstone bridge to measure the low

resistor R, the non-perfect wires resistances cant be ignored and substantially affect

the measurement. To avoid this, some modifications must be introduced. If the ratios

K/L and P/Q are equal and the bridge gets balanced, the Wheatstone condition is

again accomplished, R = (PS/Q) result of this modification

a new measuring instrument, the Kelvin Bridge, is achieved. There are some

commercial devices reaching accuracies of 2% for resistance ranges from 0.001 to 25

ohms.

PROCEDURE:


2. Required supply voltage(5v) is given using RPS.

3. The Variable resistance is varied until the galvanometer (or) ammeter showsthe zero deflection.

4. The value of resistance in DRB is noted.

5. The unknown resistance is calculated using the formula

L

K

Q

P

rLK

Lr

Q

PSR


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1. What is Kelvin bridge?

2. Draw the circuit diagram of Kelvins bridge.

3. What is Kelvins double bridge?

4. Draw the circuit diagram of Kelvins double bridge.

5. State the advantages of Kelvin double bridge method.


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6. State the usual equation used in Kelvin double bridge method.

RESULT:


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CIRCUIT DIAGRAM:


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Ex. No: AC BRIDGE MAXWELLS INDUCTANCE CAPACITANCE BRIDGE

Date:

AIM:To find the unknown value of inductance and Q factor of a given coil using

Maxwells bridge

APPARATUS REQUIRED:


1 Resistors 10 K 1

2 DLB - 1

3 DCB - 1

4 DRB - 2

5 Function generator(AFO) - 1

6 CRO - 17 Bread board - 1

8 Connecting wires - 1 Set

DESIGN:


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TABULATION:

S.No

Known Values

Actual

Value Lx

(mH)

Absolute

Value Lx

(mH)

Dissipation

Factor

D = C1R1

R3

R2

C1

F

R1

MODEL CALCULATION:


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FORMULA USED:

Lx = R2R3C1

Dissipation Factor D = C1R1 Where, = 2f

Lx Unknown inductance

THEORY:

A Maxwell Bridge (in long form, a Maxwell-Wien bridge) is a type of

wheatstone bridge used to measure an unknown inductance in terms of calibrated

resistance and capacitance. It is a real product bridge.

In the Maxwell Bridge, the resistance values of resistors R1 and R3 are known

fixed entities, and R4 and C4 are known variable entities. R4 and C4 are adjusted

until the bridge is balanced. R1 and L1 can then be calculated based on the values ofthe other components:

R1 = (R4* R3)/ R2 & L1 = R2R3C4

To avoid the difficulties associated with determining the precise value of a

variable capacitance, sometimes a fixed-value capacitor will be installed and more

than one resistor will be made variable.


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PROCEDURE:


2. Set 5v by using AFO as sine wave

3. Set the value of inductance by using DLB

4. The variable resistance and capacitance is varied until the amplitude of the

sinusoidal waveform in the CRO shows zero.5. The unknown inductance is calculated using the formulae.


1. What are the types of Maxwell bridge?

2. What is the basic working principle of Maxwell bridge?

3. What is the other name for Maxwell inductance capacitance bridge?

4. What is the quality factor for Maxwell wien bridge?

5. What are the advantages of Maxwell bridge?


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6. List out the limitation of Maxwell bridge.

7. What is the range for Maxwell bridge?

8. State the disadvantage of Maxwell wein bridge.

9. Define Q-factor of the coil.

RESULT:


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CIRCUIT DIAGRAM:


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Ex. No: AC BRIDGE SCHERINGS BRIDGE

Date:

AIM:To measure the unknown value of capacitance using Schering bridge

APPARATUS REQUIRED:


1 Resistors 10 K 1

2 DLB - 1

3 DCB - 1

4 DRB - 2


6 CRO - 1

7 Bread board - 1


DESIGN:


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TABULATION:

Frequency

(KHz)

Known Values

Actual

Value C1

(F)

Absolute

Value C1

(F)

Dissipation

Factor

D = C4R4

R3

R4

C2

F

C4

F

MODEL CALCULATION:


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FORMULA USED:

Dissipation Factor D = C4R4 Where, = 2f

C1 = C2 * (R4/R3) r1 = (R3*C4)/C2

THEORY:

A schering bridge is a bridge circuit used for measuring an unknown electrical

capacitance and its dissipation factor. The dissipation factor of a capacitor is the ratio

of its resistance to its capacitive reactance. The schering bridge is basically a four-arm

alternating-current (AC) bridge circuit whose measurement depends on balancing the

loads on its arms.

In the schering bridge, the resistance values of resistors R4 and R3 are

known, while the resistance value of resistor r1 is unknown. The Capacitancevalues of C4 and C2 are also known, while the capacitance of C1 is the value being

measured. To measure r1 and C1, the values of C4 and R3are fixed, while the values

of R4 and C1 are adjusted until the current through the ammeter between points B

and D becomes zero. This happens when the voltages at points B and D are equal,

in which case the bridge is said to be 'balanced'.

When the bridge is balanced, Z1/C2 = R3/Z3, where Z1 is the impedance of

R4 in parallel with C4 and Z3 is the impedance of r1 in series with C1. In an AC

circuit that has a capacitor, the capacitor contributes a capacitive reactance to the

impedance. The capacitive reactance of a capacitorC is 1/2fC.

As such, Z1 = R4/ [2fC4 ((1/2fC4) + R4)] = R4/ (1 + 2fC4R4) while Z3 =1/2fC1 + r1. Thus, when the bridge is balanced: 2fC4R4/ (1+2fC4R4) = r1/(1/2fC1 +r1).When the bridge is balanced, the negative and positive reactivecomponents are equal and cancel out, so

2fC1r1 = 2fC4R4 or r1 = C4R4 / C1.

PROCEDURE:


2. The Variable resistance R4 is varied until the galvanometer (or) ammeter

shows the zero deflection.

3. The unknown capacitance is calculated using the formula C1= C2 * (R4/R3).


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1. What is schering bridge?

2. Draw the circuit diagram of Schering bridge.

3. What are the advantages of schering bridge?

4. What are the measurement factors of schering bridge?

5. What is the measuring range of schering bridge?

6. What is the key advantage of schering bridge?


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7. How are the errors at low voltages rectified?

8. What is dissipation factor?

RESULT:


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CIRCUIT DIAGRAM:

MODEL GRAPH:


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AIM:To study the transient response of the RLC transient circuit

APPARATUS REQUIRED:


1 DLB - 1

2 DCB - 1

3 DRB - 1


5 CRO - 1

6 Bread board - 1


DESIGN:

Ex. No: STUDY OF TRANSIENTS

Date:


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TABULATION:

S.No System Amplitude(mV) Time(uS)

1 Critically Damped

2 Over-Damped

3 Under-Damped

PROCEDURE:

1. Make the connections as per the circuit diagram

2. Choose square wave made in signal generator and apply a suitable

input

3. Observe and plot the output waveform

4. (i) Calculate the time required by output to reach 0.368 times (RC

transient) the input value (peak).This value given practical time

constant

(ii) Calculate the time required by output to reach 0.632 times (RL

transient) the input value (peak).This value given practical time

constant


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1. What are transients?

2. Define settling time

3. Define overshoot

4. Define peak time

5. What are time domain specifications?

RESULT:


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SCHEMATIC DIAGRAM:

Primary Winding (P1)

Second (S1)

S2

Arm Displace -ment A

MODEL GRAPH:

SOFT IRON

CORE

Absolute

Reading in

Volts

LVDT Reading


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AIM:

1. To study the characteristics of an LVDT position sensor with respect tosecondary output voltage and measure the voltage due to residual

magnetism.

2. To study the characteristics of an LVDT position sensor with respect to

signal conditioning output voltage.

APPARATUS REQUIRED:1. ITB-12-CE

2. LVDT Set up

3. Multimeter (CRO)

4. Power chords

FORMULA USED:

100*ntDisplacemeMicrometer

ntDisplacemeMicrometer-ntDisplacemeCore% Error

THEORY:

The linear variable differential transformer (LVDT) is a type of electrical

transformer used for measuring linear displacement. The transformer has three

solenoid coils placed end-to-end around a tube. The centre coil is the primary, and the

two outer coils are the secondaries. A cylindrical ferromagnetic core, attached to the

object whose position is to be measured, slides along the axis of the tube. An

alternating current is driven through the primary, causing a voltage to be induced in

each secondary proportional to its mutual inductance with the primary. The frequency

is usually in the range 1 to 10 kHz. As the core moves, these mutual inductances

change, causing the voltages induced in the secondaries to change. The coils are

connected in reverse series, so that the output voltage is the difference (hence

"differential") between the two secondary voltages. When the core is in its central

position, equidistant between the two secondaries, equal but opposite voltages are

induced in these two coils, so the output voltage is zero.

When the core is displaced in one direction, the voltage in one coil increases

as the other decreases, causing the output voltage to increase from zero to a

maximum. This voltage is in phase with the primary voltage. When the core moves in

the other direction, the output voltage also increases from zero to a maximum, but its

phase is opposite to that of the primary. The magnitude of the output voltage is

proportional to the distance moved by the core (up to its limit of travel), which is why

the device is described as "linear". The phase of the voltage indicates the direction ofthe displacement. Because the sliding core does not touch the inside of the tube, it can

move without friction, making the LVDT a highly reliable device. The absence of any

sliding or rotating contacts allows the LVDT to be completely sealed against the

environment.

Ex. No: STUDY OF DISPLACEMENT TRANSDUCER - LVDT

Date:


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TABULATION:

Micrometer

Displacement

(mm)

Core

Displacement

(mm)

Secondary

Output Voltage(mv)

Signal Conditioned

Output Voltage

(mv)

% Error


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LVDTs are commonly used for position feedback in servomechanisms, and

for automated measurement in machine tools and many other industrial and scientific

applications.

PROCEDURE:

1. Install the LVDT position sensor and interface the 9 pin connector with ITB-12-CE.

2. Switch on the kit.

3. Connect the multimeter (or) CRO (in ac mv mode) across the T4 and T7 for the

secondary output voltage measurement.

4. Adjust the micrometer in 10mm displacement and turns the zero displacement

POT to 0 mm displacement on display.

5. Adjust the micrometer to 20mm displacement and turns the gain adjustment

POT to 10mm on the display.

6. Repeat the zero and span calibration until the core displacement is 0mm for

10mm displacement in micrometer and 10mm for 20mm displacement.

7. After completion of the calibration, give the displacement in micrometer to

core of the LVDT system.8. Gradually increase the micrometer displacement from 10mm to 20mm and

note down the forward core displacement from 0mm to 10mm on the display

and see the output voltage across T4 and T7.

9. Similarly decrease the micrometer displacement from 10mm to 0mm and note

down the reverse core displacement of 0 to 10mm on the display and see the

output voltage across T4 and T7.

10. Tabulate the readings of core displacement (mm), micrometer displacement

and output voltage (mv).

11. Plot the graph between core displacements (mm) along X-axis and see the

output voltage (mv) across Y-axis.

12. The same procedure repeated and note down the reverse core displacement of

0 to 10mm on the display and signal.

13. Tabulate the readings of the core displacement, micrometer displacement and

signal conditioned output voltage (V).

14. Plot the graph between core displacement (mm) along X-axis and signal

conditioned output voltage (V) along Y-axis.


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MODEL CALCULATION:


1. What is meant by transducer?

2. Mention some basic requirements of a transducer.

3. What are the classifications of transducers?

4. What is active transducer?

5. What is passive transducer?

6. What is inverse transducer?


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7. What is inductive transducer?

8. Mention some advantages of LVDT.

9. List the disadvantages of LVDT.

10. Mention the applications of LVDT.

RESULT:


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CIRCUIT DIAGRAM:


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Ex.No: INSTRUMENTATION AMPLIFIER

Date:

AIM:

To construct an instrumentation amplifier and observe the output voltagevalue.

APPARATUS REQUIRED:1. Op-amp IC-741

2. Resistor 10 K,22 K3. RPS

4. CRO

FORMULA USED:

CMRR = 20 log

Ad/A

c Ad = V0 /( V1- V2 )

Ac = 2V0 /( V1+V2 )

Where, CMRR Common Mode Rejection Ratio

Ad Difference mode gain

Ac Common mode gain

THEORY:An instrumentation (or instrumentational) amplifier is a type of differential

amplifier that has been outfitted with input buffers, which eliminate the need for input

impedance matching and thus make the amplifier particularly suitable for use in

measurement and test equipment. Additional characteristics include very low DC

offset, low drift, low noise, very high open-loop gain, very high common-mode

rejection ratio, and very high input impedances. Instrumentation amplifiers are used

where great accuracy and stability of the circuit both short- and long-term are

required.

Although the instrumentation amplifier is usually shown schematically

identical to a standard op-amp, the electronic instrumentation amp is almost always

internally composed of 3 op-amps. These are arranged so that there is one op-amp to

buffer each input (+,), and one to produce the desired output with adequate

impedance matching for the function. The ideal common-mode gain of aninstrumentation amplifier is zero. Common-mode gain is caused by mismatches in the

values of the equally-numbered resistors and by the mis-match in common mode

gains of the two input op-amps. Obtaining very closely matched resistors is a

significant difficulty in fabricating these circuits, as is optimizing the common mode

performance of the input op-amps.

An instrumentation amp can also be built with 2 op-amps to save on cost and

increase CMRR, but the gain must be higher than 2 (+6 dB).


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TABULATION:

Differential mode:

S. No

Input Voltage

Output Voltage V0

(V)

Difference Mode Gain

Ad = V0 /( V1- V2 )

V1

(V)

V2

(V)

DESIGN:


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Procedure:


2. Supply is given through switches.

3. Different voltages are set as two inputs for different mode.4. The output is observed in voltmeter.

5. The same voltage is set in two inputs for common mode.

6. The output is observed in voltmeter.

7. The value of Ad and Ac are calculated using formula.


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MODEL CALCULATION:


1. Features of instrumentation amplifier.

2. What is mean by CMRR?


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3. Characteristics of instrumentation amplifier.

4. Applications of instrumentation amplifier.

RESULT:


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CIRCUIT DIAGRAM:

R1

1k

21

M

P1C

P

L1

10uH

1 2

V P2

10A

FUSE

C1

(0-10)A

10A

FUSE

L C2L1

10uH

1 2

R1

1k

21

MODEL GRAPH:

% Error Current


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Ex.No: CALIBRATION OF SINGLE PHASE ENERGY METER

Date:

AIM:To calibrate the given wattmeter and energy meter by direct loading.

APPARATUS REQUIRED:


1

2

3

4

5

6

7

8

Ammeter

Voltmeter

Wattmeter

Resistive load

1 auto transformer

Energy meter

Connecting wires

Screw driver

(0-10A)MI

(0-300V)MI

300V,10A,UPF

-

-

240V,50HZ,1200rev/KWhr

-

-

1

1

1

1

1

1

Few

1

FORMULA USED:

hrKWTrueenergy /1000*3600

)time(sec*Watt

hrKWgyActualener /

constantmeterEnergy

srevolutionofNo

= 10/1200 =8.33 * 10-3

100*

energyTrue

energyTrue-energyActual% Error


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TABULATION:

Voltmeter

Reading

(V)

Ammeter

Reading

(A)

Time for 10

Revolutions

(Sec)

Wattmeter

Reading

(Watt)

True

Energy

(KW/Hr)% Error

MODEL CALCULATION:


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THEORY:

Calibrating the energy meter means to find out the error in the measurement of

energy by energymeter.Every energy meter has its own characteristics constant

specified by the manufacturer which relates the energy measured in joules and the

number of revolutions of the disc. For example say X revolutions corresponds to themeasurement of Y joules. But practically the value of X is very large and cannot be

measured in the laboratory. Hence using this constant energy recorded for certain less

number of revolutions say 5, is calculated in the laboratory for the calibration

purpose. This energy is denoted as Er. Thus Er can be calculated from X as Er =

(5X)/Y joules

To have zero error, the actual energy consumed by the load for the time

corresponding to the 5 revolutions must be same as E r .this energy is called actual

energy consumed are the true energy denoted as Et. For various loads, the time

required to complete the 5 revolutions of disc is measured with the help of stop watch.

The percentage of error can be calculated by

100*energyTrue

energyTrue-energyActual% Error

PROCEDURE:


2. By varying the auto transformer rated voltage is set and no load readings are

taken.

3. There by applying the load, ammeter, voltmeter, wattmeter and other energy

readings are noted.


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1. What is calibration?

2. What is the significance of calibration?

3. What are the different calibration methodologies?

4. Why calibration of instrument is important?

5. What are the types of energy meters?

6. Name the constructional parts of induction type energy meter.

7. How voltage coil is connected in induction type energy meter?


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8. How current coil is connected in induction type energy meter?

9. What is the purpose of registering mechanism?

10. What is the purpose of braking mechanism?

RESULT:


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CIRCUIT DIAGRAM:


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AIM:To study the performance of current transformer and to find out the

transformation ratio.

APPARATUS REQUIRED:

1. VPL-01 ACC module

2. Current transformer

3. Ammeter

FORMULA USED:

Transformation ratio K = I1/I2

Error = I1-I2

Where, I1 Primary current in Amps

I2 Secondary current in Amps

THEORY:A current transformer (CT) is used for measurement of electric currents.

Current transformers are also known as instrument transformers. When current in a

circuit is too high to directly apply to measuring instruments, a current transformer

produces a reduced current accurately proportional to the current in the circuit, which

can be conveniently connected to measuring and recording instruments. A current

transformer also isolates the measuring instruments from what may be very high

voltage in the primary circuit.

For a current transformer, it is necessary that the transformation ratio must be

exactly equal to turns ratio and phase of the secondary turns must be displaced by 180

degree from that of the primary turns .Two types of errors affect these characteristics

of an current transformer which are ratio error, phase angle error.

Ex.No: CALIBRATION OF CURRENT TRANSFORMER

Date:


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TABULATION:

Primary

Current I1

(A)

Secondary

Current I2

(A)

Transformation Ratio

K = I1/I2

Error = I1 - I2

MODEL GRAPH:


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MODEL CALCULATION:

PROCEDURE:

1. Connect the output 1 to the current transformer of P1.

2. Connect the output 2 to the current transformer of P2.

3. Connect the current transformer S1 to ammeter 5th

Pin.

4. Connect the current transformer S2 to ammeter 2nd

Pin.

5. Connect 230V AC supply to meter of 6th

and 8th

Pin (6th

line, 8th

neutral).

6. Initially kept in current adjustment pin at 0.

7. Switch ON Kit. Vary the current source and take the readings till the primarycurrent reaches 15A.

8. Tabulate the primary and secondary output values.


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1. What is transformer?

2. What is meant by instrument transformer?

3. What are the types of instrument transformer?

4. List out the Limitation of instrument transformer.

5. What are the types of error in current transformer?


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6. Define ratio error.

7. How the phase angle error is created?

RESULT:


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CIRCUIT DIAGRAM:

DIGITAL TO ANALOG CONVERTER:

MODEL GRAPH:


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Ex.No: D-A CONVERTER

Date:

AIM:

To construct and test the R-2R ladder network D-A converter.

APPARATUS REQUIRED:


1

2

3

4

5

6

7

Resistor

Voltmeter

IC741

RPS

Dual RPS

Bread Board

Connecting wires

10K,2.2K

(0-10V) MC

--

(0-30V)

(0-15V)

-

4

1

1

1

1

1

few

THEORY:In electronics, a digital-to-analog converter (DAC or D-to-A) is a device for

converting a digital (usually binary) code to an analog signal (current, voltage or

electric charge). A DAC converts an abstract finite-precision number (usually a fixed-

point binary number) into a concrete physical quantity (e.g., a voltage or a pressure).

In particular, DACs are often used to convert finite-precision time series data to a

continually-varying physical signal.

A typical DAC converts the abstract numbers into a concrete sequence of

impulses that are then processed by a reconstruction filter using some form of

interpolation to fill in data between the impulses. Other DAC methods (e.g., methods

based on Delta-sigma modulation) produce a pulse-density modulated signal that can

then be filtered in a similar way to produce a smoothly-varying signal. Most modern

audio signals are stored in digital form (for example MP3s and CDs) and in order to

be heard through speakers they must be converted into an analog signal. Applications,

DACs are therefore found in CD players, digital music players, and PC sound cardsVideo signals from a digital source, such as a computer, must be converted to analog

form if they are to be displayed on an analog monitor. A device that is distantly

related to the DAC is the digitally controlled potentiometer, used to control an analog

signal digitally.


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TABULATION:

Digital Input

Analog Output V0

(Volt)

A B C

PIN DETAIL:


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PROCEDURE:


2. Set the input voltage and note down the output voltage using multimeter.

3. By varying the input voltage different output voltages are noted.

4. Outputs are verified using truth table.


1. List the broad classification of ADCs.

2. What is integrating type converter?

3. Explain in brief the principle of operation of successive Approximation ADC.

4. What are the main advantages of integrating type ADCs?


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5. Where is the successive approximation type ADCs used?

356. Define conversion time.

7. Define resolution of a data converter.

8. Define accuracy of converter.

9. What is settling time?

10. What is monotonic DAC?


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11. What is a sample and hold circuit? Where it is used?

12. Define sample period and hold period.

RESULT:


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MODEL GRAPH:

1) Gauge Pressure Vs Bridge Voltage

2) Gauge Pressure Vs Output Voltage

3) Gauge Pressure Vs % Error


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Ex. No: STUDY OF PRESSURE TRANSDUCER

Date:

AIM:

To study the characteristics of the pressure coil with respect to bridge voltage

and signal conditioned output voltage.

APPARATUS REQUIRED:

1. ITB-16-CE trainer kit

2. Pressure coil Set up

3. Multimeter

4. Power chords

FORMULA USED:

100*PressureDisplayed

PressureDisplayed-PressureGauge% Error

THEORY: A strain gauge is a device used to measure the strain of an object. The strain

gauge consists of an insulating flexible backing which supports a metallic foil pattern.

The gauge is attached to the object by a suitable adhesive .As the object is deformed,

the foil is deformed, causing its electrical resistance to change. This resistance

change, usually measured using a Wheatstone bridge, is related to the strain by the

quantity known as the gauge factor.

A strain gauge takes advantage of the physical property of electrical

conductance's dependence on not merely the electrical conductivity of a conductor,which is a property of its material, but also the conductor's geometry. When an

electrical conductor is stretched within the limits of its elasticity such that it does not

break or permanently deform, it will become narrower and longer, changes that

increase its electrical resistance end-to-end. Conversely, when a conductor is

compressed such that it does not buckle, it will broaden and shorten changes that

decrease its electrical resistance end-to-end. From the measured electrical resistance

of the strain gauge, the amount of applied stress may be inferred. A typical strain

gauge arranges a long, thin conductive strip in a zigzag pattern of parallel lines such

that a small amount of stress in the direction of the orientation of the parallel lines

results in a multiplicatively larger strain over the effective length of the conductor and

hence a multiplicatively larger change in resistance than would be observed with a

single straight-line conductive wire.


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PROCEDURE:

(a) Gauge Pressure Vs Bridge Voltage1. Install the Pressure coil Set up and interface the 9 pin connector with ITB-16-

CE.

2. Connect the multimeter (or) CRO (in ac mv mode) across the T2 and T3 for the

bridge voltage measurement.3. Switch on the kit.

4. Initially open the air release valve and exhaust tank inlet air and nullify the

bridge voltage by using zero adjustment POT.

5. Now choose the opened air release valves, by pressing the pump piston. The

pump sucks the air atmosphere and supplies it to the cylinder. Then the

pressure will be developed in the cylinder and now measure the bridge voltage

(mv) across T2 and T3.

6. Gradually increase the pressure by pressing the pump piston and note down

the bridge voltage (mv) for corresponding gauge pressure.

7. Tabulate the readings and put a graph between gauge pressure and bridge

voltage.

(b) Gauge Pressure Vs Signal Conditioned Voltage1. Install the pressure coil set up and interface the 9 pin D connector with ITB-

16-CE.

2. Connect the multimeter (or) CRO (in ac mv mode) across the T5 and ground

for the signal conditioned voltage measurement.

3. Switch on the kit.

4. Initially open the air release valve and exhaust tank inlet air and nullify the

signal conditioned voltage by using zero adjustment POT.

5. Now close the opened air release valve and apply the pressure of 50 psig to the

cylinder and adjust the display to 50 psig by using gain adjustment POT.

6. After the gain calibration open the air release valve and exhaust tank inlet air.

7. Again close the opened air release valve by pressing the pump piston, the

pump sucks the air atmosphere and supply it to the cylinder. Then the pressure

will be developed in the cylinder and measure the signal conditioned voltage

(mv) across T5 and ground.

8. Gradually increase the pressure by pressing the pump piston and note down

the signal conditioned output voltage (mv) for corresponding gauge pressure.

9. Tabulate the readings and put a graph between gauge pressure and signal

conditioned output voltage


1. What is the purpose of strain gauge?


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2. Define strain gauges.

3. Define gauge factor.

4. What is meant by Poissons ratio?

5. Mention types of strain gauges.

6. What are the advantages of semiconductor strain gauges?

7. What are disadvantages of strain gauge?

RESULT:


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CIRCUIT DIAGRAM:


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Ex.No: MEASUREMENT OF THREE PHASE POWER AND POWER

FACTOR

Date:

AIM:To measure the three phase power using two wattmeter method and also find

the power factor value.

APPARATUS REQUIRED:


1

2

3

4

5

6

Ammeter

Voltmeter

Wattmeter

Three phase Resistive load

Three phase autotransformer

Connecting wires

(0-10A)MI

(0-600V)MI

600V,10A,UPF

-

-

-

1

1

2

1

1

Few

FORMULA USED:

Total Power W = W1+W2 watts

Where, W1&W2Wattmeter Readings

Total Power W = 3 VLIL cos

VL & IL Load Voltage and Current

THEORY:

In 3 circuits whether the load is star connected or delta connected, total 3power is given by 3 VLILcos. The is the angle between Vph and Iph. The power ismeasured by using wattmeters. Wattmeter is a device which gives power reading,

when connected in 1 or 3 system, directly in watts. It consists of two coils 1.

Current coil, 2.voltage coil (or) pressure coil. The current coils of the two wattmeterare connected in any two lines while the voltage coil of each wattmeter is connected

between its own current coil terminal and the line without a current coil. For example,

the current coils are inserted in the lines R and Y then the pressure coils are connected

between R B for one wattmeter and Y B for other wattmeter. The connections are

same for star or delta connected load. In two wattmeter method, the algebraic sum of

the two wattmeter reading gives the total power dissipated in the 3 circuit. If W1&W2 are the two wattmeter readings then the total power W= W1+W2 in watts


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TABULATION:

Load Load

Current

(A)

Supply

Voltage

(V)

Wattmeter

Reading

(Watts)

Total Power

W= W1+W2

(Watts)

Power Factor

cos

=W /3VLIL

Total

PowerW =3VLIL cos

(Watts)

W1 W2


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PROCEDURE:


2. The total voltage is given by adjust the autotransformer.

3. The meter readings are note down at no load conditions.4. By applying the load gradually the corresponding meter readings are noted

down.

5. The above procedure is repeated for different input voltage by adjust the

autotransformer.

6. The load is released gradually and the supply is switched off.

MODEL CALCULATION:


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1. What is balanced voltage?

2. What is balanced impedance?

3. What is phase sequence?

4. Write the relation between the line and phase value of voltage and current in a

balanced

star connected source load.

5. Write the relation between the line and the phase value of voltage and current

in a

balanced delta connected source/load.

6. Write the relation between the power factor wattmeter readings in two

wattmeter

method of power measurement.


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7. Name the methods used for power measurement in three phase circuits.

8. Name the methods used in Wattmeter calibration.

RESULT:


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Ex.No: MEASUREMENT OF IRON LOSS (MAXWELL BRIDGE)

Date:

AIM:To measure and study the iron loss and permeability of given ring specimen.

APPARATUS REQUIRED:1. ITB- 26B unit

2. Patch chords

3. Multimeter

4. Microphone

FORMULA USED:

At balance condition,

Unknown inductance Ls = Std R1* Std R3*C

Unknown Resistance Rs = (Std R1* Std R3) / R2 Unknown Permeability = (ls R1 R3C) / N

2As

Where, Rs Specimen resistance in

R2 Standard resistance measured by using multimeter across POT 2

in

ls Specimen winding length in mm

R1 & R3 Standard resistances in

C

Capacitance in F

THEORY:

To measure iron loss and permeability in an accurate manner we use

maxwells inductance bridge in a sensitive way. Maxwells bridge is use to measure

unknown inductance of the coil which is connected in one arm of the bridge circuit.

Measurement of iron loss and permeability of ring specimen unit contains the

following three major parts as follows.

Oscillator Maxwells Bridge Output detector.

In a specimen the iron loss meant for the power loss due to magnetization

loss. The power loss in a ring specimen includes both copper loss and iron loss. In our

instrument specimen made up moulded ferrite core, so the total power loss is equal to

iron loss = IL2(Rs - Rw).The iron loss unit in terms of mw (or)w. Permeability of an

ring specimen dependent upon the following parameter namely length of the winding

number of turns, area of the specimen and the arm parameters. Normally these values

are given by the specimen manufacturers.


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Permeability

=(l

sR

1R

3C)/

N2A

s

Iron

Loss =

I12(R

S

-

Rw)

Specimen

Resistanc

e Rs

Specimen

Inductance

Practical

(mH)

Specimen

Inductance

(mH)

I1(mA)

Winding

Resistanc

e

Rw

()

Std

Resistanc

e

R2P

OT(

)

Std

Resistanc

e R1

POT(

)

S

td

Re

sist

ance

R

3

()

PROCEDURE:


2. Connect the ring specimen to the arm for which measured to be made.

3. Keep the POT 2 in maximum position and switch ON the unit.

TABULATION:


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4. The output can be detected either by microphone (or) CRO multimeter.

5. For detecting the output by CRO, vary the POT 1 from lower to higher value

at particular point the output goes to minimum value.

6. Note down the resistance by using multimeter.

7. In this condition note down the AC current through ring specimen POT 2 &

the source current by using multimeter.

8. Apply those values in to an approximated formula and find out the iron loss ofthe ring specimen.

9. Similarly proceed the same procedure for the given three ring specimen.

MODEL CALCULATION:


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CIRCUIT DIAGRAM:

SPECIMEN TECHNICAL DETAILS:

Specimen Value

mH

Length ls

m

Number of Turns

N

Area As

(cm2)


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1. What is meant by iron loss?

2. What are the different methods of measuring Iron loss?

3. Which type of bridge is used to measure iron loss?

4. What are the reasons for using Bridge method?

5. What is the limitation of wattmeter method?

RESULT:


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ee38 measurments & instrumentation lab

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