MAHAVEER INSTITUTE OF SCIENCE & TECHNOLOGY

MAHAVEER INSTITUTE OF SCIENCE & TECHNOLOGY

BANDLAGUDA, HYDERBAD - 500 005.

Deparment of ELECTRICAL & ELCTRONICS ENGINEERING

ELECTRICAL MEASUREMENTS LAB

LIST OF EXPERIMENTS

1. Calibration and Testing of Single Phase Energy Meter.

2. Calibration of Dynamometer power factor meter.

3. Crompton D.C. Potentiometer-Calibration of PMMC Ammeter and PMMC Volt meter.

4. Kelvin double bridge-Measurement of Resistance-Determination of Tolerance.

5. Dielectric oil testing using H.T.Testing kit.

6. Schering Bridge and Anderson bridge.

7. Measurement of 3-phase reactive power with single-phase wattmeter.

8. Measurement of parameters of choke coil using 3 voltmeter and 3 ammeter method.

9. Calibration LPF wattmeter-by Phantom testing.

10. Measurement of 3 phase power with single wattmeter and 2no”s of C.T.

11. C.T. testing using mutual inductor-measurement of % ratio error and phase angle of given C.T.by

Null method.

12. P.T.testing by comparison-V.G. as Null detector- measurement of % ratio error & phase

angle of given P.T.

13. LVDT and Capacitance pickup-characteristic and calibration.

14. Resistance Strain Gauge-Strain measurement and calibration.

15. Transformer turns ratio measurement using A.c. Bridge.

16. Measurement of % ratio error and phase angle of given C.T.by Comparison method.

ADDITIONAL EXPERIMENTS 1. Measurement of Earth resistance using digital earth tester. 2. Measurement of Insulation resistance using digital Insulation tester.

MIST-ELECTRICAL MEASUREMENTS LAB MANUAL

1. CALIBRATION AND TESTING OF SINGLE PHASE ENERGY METER

Aim:

To Measure the % error in given Energy meter.

Apparatus Required:

Sl. No.

Description

Type

Range

Quantity

01

Sub standard Energy Meter

Induction

240V,(5-10)A, 50 Hz

01

02

Test standard energy meter

1- Φ

230 / (0-270)V,

(0-10)A

01

03

Voltmeter

MI

(0-300)V

01

04

Ammeter

MI

(0-10)A

01

06

Water Load

230V, (0-10)A

01

07

Stop Watch

Digital

------

01

08 Connecting

Wires ------ ------

As required

MIST-ELECTR

ELECTRICAL MEASUREMENTS LAB MANUALMANUAL

Procedure: 1. Make the connections as per the cicuit diagram. 2. Switch ON DPST Switch apply the water load by rotating the metal

loads in clockwise direction. 3. Count the number of pulses made by the Standard meter within the

internal say 3 minutes or 5 minutes and at the same time counts the number of revolutions using stop watch.

4. Repeat the procedure for different loads tabulate the readings and the error.

5. Find the error in given energy meter with the given formulae.

Precautions: 1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings. 3. If the energy meter rotate in reverse direction change either its

Current coil terminals or pressure coil terminal but not both Observation Table:

Sl

No.

Tim(min)

Current

(I)

No. of pulses in standard meter(Ns)

Energy read by standard meter(Nx)

Energy

read by

standar

d meter

(Em)

Energy

read by

test

meter)

(Et)

% Error =

(Em - Et)/

Em X 100

Page | 20

Theoretical Calculations: Ks=6400,Ns=400,Kx=600, Nx=35

Energy read by standard meter reading (or) measured value Em= (Ns/Ks) Energy read by test meter reading (or) true value Et= (Nx/Kx)

% Error = [(Em - Et)/ Em] X 100 where Em= measured value Et =actual value

Result:

Page | 21


2.Calibration and testing of dynamometer type power factor meter

Aim: To measure the error in given power factor meter

Sl. No.

apparatus

Type

Range

Quantity

01

Power

factor meter

------

230 v,5/10

ohm

01

02

AMMETER MI (0-10)A

01

03

WATTMETER

UPF

600 V,10 A

01

04

VOLTMETER

MI (0-300)V

01

05

CURRENT INJECTION

UNIT

------

500 V/10 OHM

01

06

PHASE SHAFT TRANSFORMER

------

440 V 3PHASE 50HZ

01

Page | 22

Page | 23


Procedure: 1. Connect the circuit as per the circuit diagram. 2. Adjust the current in current coil to around 3A or 5A using c t.

3. Adjust the potential in pressure coil to around 200V or 300V using transformer

4. Adjust the phase shaft fine dial such that power factor meter reads unity and tabulate wattmeter , ammeter, power factor meter and voltmeter readings.

5. With phase shafting warse dial obtain the readings in power factor in differential conditions that is leading and lagging.

6. Tabular atleast tow readings in both conditions

Precautions:

1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings 3. If the energy meter rotate in reverse direction, change either it’s

current coil terminals or pressure coil terminal but not both.

Observation Table:

Lead/lag loads

V(v) I(a) P.F. cosθ

W(w) cosϕ=W/VI ϕ= cos-1

cosθ

Calculation of angle of power factor (θ )

Error power factor

Error in angle

Page | 24


Theoretical Calculations:

Error in power factor=cosθ -cosϕ

Error in angle=θ-ϕ

Result:

Page | 25


3.CROMPTON DC POTENTIOMETER – CALIBRATION OF PMMC AMMETER & PMMC VOLTMETER

Aim: To measure the unknown voltage using DC Crompton Potentiometer

and calibration of voltmeter and ammeter

Apparatus required:

Sl. No.

Description

Type

Range

Quantity

1

Potentiometer

D.C

----

01

2

Stabilizer

-----

(0-300v)

01

3

Rheostat

Wire wound

110/5A

01

4

Standard cell

dry

1.018 v

01

5

Galvanometer

Analog

(0-

100)mA

01

6

Voltmeter

MC

(0-300)V

01

7

Ammeter

MC

(0-5)A

01

8

patch cards

-----

-----

As required

Page | 26


Kit Diagram:

Page | 27


Circuit Diagram:

Page | 28


Page | 29


Procedure:

Initial calibrations Fixing working current 1. Connect the battery, galvanometer in the kit as shown in the circuit diagram. 2. Put the switch ‘S’ in the standard cell position and connect the

standard cell to the standard knob. 3. Rotate the main dial and slide wire in order to get the same voltage of the

standard emf. 4. Now press the key and observe the galvanometer deflection. 5. If the galvanometer does not show the balance position, adjust the rheostat

and make it to read zero.

To find unknown emf: 1. Connect the unknown battery across the knob marked ‘X’ 2. Put the switch ‘S’ in the unknown emf position. 3. Adjust the main dial slide wire to get the null position in the

galvanometer. 4. The reading in the main dial and slide wire gives the voltage of the

unknown cell.

CALIBRATION OF AMMETER: 1. Made the connections as per the circuit diagram. 2. A standard resistance of suitable value and sufficient current

Carrying capacity is placed in series with the Ammeter under calibration.

3. The voltage across the standard resistance is measured with the help of potentiometer and the current through the standard resistance can be compound current I= Vs / S amps.

5. Since the resistance of standard resistor is accurately known and the voltage across the standard resistor is measured by a potentiometer, this method of calibrating an Ammeter is very accurate.

6. A calibration curve indicating the errors at various scale reading of the ammeter may be plotted

Page | 30

CALIBRATION OF VOLTMETER: 1. Made the connections as per the circuit diagram. 2. The first and foremost requirement in this calibration is that a Suitable

stable DC voltage supply is available since any changes in the supply voltage will cause a corresponding change in the voltmeter calibration.

3. The figure given is a potential divides, consisting of two rheostats, One or course and the other for fine control of calibrating voltage.

4. These controls are connected to the supply source and with the help Of these controls it is possible to adjust the voltage so that the pointer coincides exactly with a major division of the voltmeter.

7. The voltage across the voltmeter is stepped down to a value suitable for application to a potentiometer with the help of a volt- Ratio Box for accuracy of measurement, it is necessary to measure voltages near the maximum range of the potentiometer, as for as possible.

8. Thus the potentiometer has a maximum range of 1.6V. To achieve high accuracy we will have to use low voltage ranges for voltages less than 1.6V and use appropriate tapping’s on volts ratio box for voltages higher than 1.6V.

Precautions:

1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their

Ratings 3. Observe the ammeter reading. Apply the voltage slowly

So that the current is within the limited range of ammeters 4. Handle the Bridge carefully.

Page | 31

Observation Tables:

Measurement of unknown emf:

S.No. True Value of Unknown EMF (Volts)

Measured Value of Unknown EMF (Volts)

% Error

CALIBRAION OF AMMETER:

Sl. No.

Current (Iin) Amps

Current (Iout) Amps

% Error ((Iout - Iin ) / Iou ) x

100

Page | 32


CALIBRATION OF VOLTMETER:

Sl. No.

Voltage (Vin) Volts

Voltage (Vout) Volts

% Error (Vout - Vin ) / Vou ) x

100

Result:

Page | 33


Aim:

4.KELVIN’S DOUBLE BRIDGE

To measure the of low resistance of shunt with Kelvin’s double bridge.

Apparatus Required:

Sl. No.

Description

Type

Range

Quantity

1

Portable Kelvin’s double bridge Kit

----

----

01

2

Galvanometer

Analog

(0-100)mA

01

3

patch cards

----

----

As

required

Procedure: 1. Connect the Kelvin double bridge to galvanometer and power supply

as per the circuit diagram. 2. Adjust the multiples as per given shunt. 3. Adjust the ammeter less than given shunt. 4. Put the current in normal direction and check the galvanometer in intial

position if zero. 5. On the final switch nand there will be a change in galvanometer.By moving

the dail put the galvanometer to zero and not the reading on dail. 6. In similar way do the procedure in reverse current and repeat the experiment

for different shunts. 7. Switch OFF the power supply.

MIST-ELECTRICAL

CIRCUIT DIAGRAM

Precautions: 1. There should not be any2. Meter readings should not3. Handle the Bridge very

ELECTRICAL MEASUREMENTS LAB MANUAL

KELVIN ‘S DOUBLE BRIDGE

any loose connections. not be exceeded beyond their ratings

very carefully

Page | 34

MANUAL

Page | 35


Observation Table:

Sl. No.

I amps

Normal Resistance Rn (Ω)

Reverse resistance Rn(Ω)

Shunt average= average of normal reverse resistance

Page | 36



Shunt average=normal resistance + reverse resistance/2 =Rn+Rr/2 RESULT:-

Page | 37


5.DIELECTRIC STRENGTH OF TRANSFORMERS OIL Aim:- To determine the dielectric strength of transformer oil by using of oil testing oil. Apparatus required:- s.no Apparatus name Range Quantity 1 Oil testing kit -- --

2 Test cell with electrodes -- --

3 New transformer oil(1/2 lit)

-- --

Procedure:-

1. Clean the oil test cell carefully and adjust the space gap to 2.5mm.

2. Pour the oil up to level mark.

3. Place the test cell in position and close the led.

4. Switch on the test kit keeping it in minimum position and switch on.

5. Rasie the voltage in auto position till the Vλ .Note the Vλ voltage.

6. Repeat the experiment and task 6 observation Note: THE OBSERVATIONS SHOULT NOT DEFER BY MORE THAN 10 7.Repeat the above experiment for gap spacing of 1mm,2mm,3mm,4mm and 5mm. 8.plot the graph.

OBSERVATION TABLE:-

S.no Gap space Bd voltage Average value

Theoretical Calculations: Vd=V0(d)^n Ln(Vd)=1n(V0)+n 1n(d) To find V0 put d=1mm corresponding Vd=V0 To find n, substitute d=2.5mm

Result:-

Page | 38


Aim:

6. SCHERING BRIDGE To measure the unknow capacitane by using schering bridge.

Apparatus Required:

Sl. No.

Description

Type

Range

Quantity

1

Schering bridge kit

----

----

01

2

Head Phones

----

----

01

3

patch cards

----

----

As per required

Procedure:

1. Make the connection as shown in figure by using ac supply of

frequency 1KHZ and head phones.Connect one unknown capacitance as shown.

2. Set the capacitance dail C2 at zero position and R also at zero position.

3. Now introdudce some resistance from decade resistance and dial R say 1000Ω and adjust the decade resistance. Dial R to minimum sound in the head phones.

4. Note down the values of R1 and R2,also note the value of C1. 5. Calculate the value of unknown capacitance by using formula i.e.,

C=R2/R1R*C1. 6. Repeat the experiment with different values of unknown resistance.

CIRCUIT DIAGRAM

Precautions:

1. There should not be any2. Handle the Bridge very

any loose connections. very carefully.

Page | 39

Page | 10

Observation Table:

Sl. No.

R1 (Ohms)

R2 (Ohms)

C1 (µ farads)

C=R2/R1*C1 (m farads)

Page | 11


Unknown Capacitance C = (R2/R1) × C1

Result:

Page | 12


Aim:

6 (b).ANDERSON BRIDGE

To measure the self-inductance of the given coil using Anderson’s bridge.

Apparatus Required:

Sl. No.

Description

Type

Range

Quantity

1

Anderson’s Bridge kit

----

----

01

2

Head Phones

----

----

01

3

patch cards

----

----

As per required

Procedure:

1. DC-BALANCE (null point) a) Make the connections as per the circuit diagram. b) Now adjust the resistance dial R and press the potentiometer key and

get the balance in the point. c) Use the resistance dial R only for fine balance galvanometer and note

the values. 2.AC-BALANCE a) make the connections as per circuit diagram.

b) now adjust the resistance dial R and check the volume in the head phone if it reads less.

c) set the r dial to 0.1µf. d) use the resistance dial R only for low volume in the head phones and note down values.

MIST-ELECTRICAL

CIRCUIT DIAGRAM

Precautions:

1. There should not2. Handle the Bridge

ELECTRICAL MEASUREMENTS LAB MANUAL

CIRCUIT DIAGRAM

ANDERSON BRIDGE

not be any loose connections. Bridge very carefully.

Page | 13

MANUAL

Page | 14

Observation Table:

Sl. No.

R Ώ

rΏ

L Ώ

C(mh) Ώ

Page | 15


Result:

Page | 16


7.MEASUREMENT OF 3- PHASE REACTIVE POWER USING ONE WATTMETER

Aim: To measure the total reactive power iun a circuit using one wattmeter method

Apparatus Required:

Sl. No.

Description Type Range Quantity

01

wattmeter UPF

600 v /(5/10)A

01

02

Ammeter

MI

(0-5/10)A

01

03

Voltmeter

MI

(0-600)V

01

04

rheostat

Wire wound 25 OHMS /5A 03

05

3phase variable capacitive load

------

(0-10)A 01

06

Connecting Wires

----- ------

As required

MIST-ELECTRICAL


Page | 17

LAB MANUAL

Page | 30


Procedure:

1.Connect the circuit as per the circuit diagram. 2.Set three phase auto Transformer at zero voltage position before switching on the supply. 3.Gradually increase the voltage using the auto-transformer till the voltmeter reads rated line voltage. 4.Now apply the three phase balanced inductive load in steps. 5.For each step note down the Voltmeter, Ammeter & Wattmeter readings. 6.After noting the values slowly decrease the auto transformer till Voltmeters come to zero voltage position and switch off the supply. 7. Calculate the % Error and draw the graph between

% Error and load current

Precautions: 1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their

Ratings 3. Readings of the meters must be taking without parallax error.

Observation Table:

S.No

V(V)

I(a)

W (wats)

Q (var)

Page | 31



Reactive PowerW= √3VISINФ

Result:

Page | 32


8.Measurement of parameters of a choke coil using by 3-voltmeter and 3-Ammeter method

Aim: To Measure the power and parameters of choke coil using by 3-voltmeter and 3-Ammeter

method

Sl. No.

Description

Type

Range

Quantity

01

Auto

Transformer

1- Φ

230 / (0- 270)V, (0-10)A

01

02

U.P.F. Wattmeter

Dynamometer Type

300V/10A

01

03

Voltmeter

MI

(0-300)V

01

04

Ammeter

MI

(0-500)mA 01

05

Rheostat

1- Φ

300,ohms (0-

1.7)A

01

06

Connecting

Wires

-----

-----

As

required

MIST-ELECTRICALELECTRICAL MEASUREMENTS LAB MANUAL

Page | 33

MANUAL

Page | 34


Procedure: 1.Connect the circuit as per the circuit diagram. 2.Increase the supply voltage from 50v to 150 v insteps of 20v. 3.Take the reading of voltmeter ammeter and wattmeter. 4.Calculate the power and parameters of the choke coil.

Precautions: 1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings

Observation Table:

Sl

No.

Vs

(v)

Vl

(v)

Vr

(v)

I

(ma)

cosØ

P

Sin Ø

Z=Vl/I

R=ZcosØ(Ω)

XL= ZsinØ(Ω)

L=(mh)

Page | 35

(B)3-Ammeters method

Apparatus Required:

Sl. No.

Description

Type

Range

Quantity

01

Ammeter M-I

0-10 A

03

02

Voltmeter

MI

(0-300)V 01

03

Digital multimeter

-

01

04

1 Ø variac

-

230V/60A

01

05

Rheostat

Wire

wounded

45Ω

01

06

wattmeter

UPF

300V/2A

01

07

Connecting Wires ------ ------

As required

Page | 36


Procedure: 1. Connect the circuit as per the circuit diagram. 2. Set single phase auto Transformer at zero voltage position before

switching on the supply. 3. Gradually increase the voltage using the auto-transformer till the

supply voltmeter reads rated voltage. 4. Now change the current through choke coil by varying the shunt

rheostat of choke coil in steps. 5. For each step note down the three Ammeters and one voltmeter

readings. 6. After noting the values slowly decrease the auto transformer till

Voltmeters come to zero voltage position and switch off the supply. 7. Calculate the parameters of choke coil for each current and tabulated in the

tabular column.

Precautions: 1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings 3. Readings of the meters must be taking without parallax error. 4. Ensure that setting of the Auto Transformer at zero output voltage During

starting

Observation Table: S.No

V(v)

Ir

I

L

IS

W (w)

cosΦ

R= V/Ir (Ω)

ZL= V/iL (Ω)

RL=

ZLcosØ

(Ω)

XL=

√ZL²-RL² (Ω)

Wa L

Page | 37



CosΦ= (IS2-IL

2 –IR 2) / 2ILIR Power Wa=VILcosØ L=XL/2πf

Result:

Page | 38


Aim:

9.CALIBRATION OF LPF WATTMETER - BY DIRECT LOADING

To calibrate the given LPF Wattmeter by direct loading

Apparatus Required:

Sl. No.

description

Type

Range

Quantity

01

Auto Transformer

1- Φ

230/(0270)V,10A

01

02

L.P.F. Wattmeter Dynamometer

Type 300 V/10A 01

03

Voltmeter

MI

(0-300)V

01

04

Ammeter

MI

(0-5)A

01

05

Inductive Load

1- Φ

0-150mH,10A

01

06

Connecting Wires

------ ------ As

required

MIST-ELECTRICAL


Page | 39

LAB MANUAL

Page | 40


Procedure:

1. Connect the circuit as per circuit diagram. 2. Set single phase auto Transformer at zero voltage position before

switching on the supply. 3. Gradually increase the voltage using the auto-transformer till the

supply voltmeter reads rated voltage. 4. Now apply the single phase balanced inductive load in steps. 5. For each step note down the voltmeter, Ammeter, PF meter and

wattmeter readings. 6. After noting the values slowly decrease the auto transformer till

Voltmeter come to zero voltage position and switch off the supply. 7. Calculate the % Error and draw the graph between % Error and load

current. Precautions:

1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings. 3. Readings of the meters must be taking without parallax error. 4. Ensure that setting of the Auto Transformer at zero output voltage During

starting

Observation Table:

Sl. No.

V

I

P.F CosΦ

Wattmeter Reading

(or) Measured value(Wm)

Actual value

(Wt) = VI Cosф

%Error

Page | 41



% Error = [(Wm - Wt)/ Wt] X 100

Where Wm= measured value

Wt =actual value

Result:

Page | 42


10. Aim:

MEASUREMENT OF REAL POWER IN 3- Ф CIRCUIT

To measure the real popup in a 3- Ф circuit

Apparatus Required:

Sl. No.

Apparatus

Type

Range

Quant

ity

1 Ammeter

MI (0-10)A

01

2

voltmeter

MI

(0-600)v

01

3

Current transformer

250/5A

---

02

4 Capacitive load 230V,6A --- 01

5 rheostat WIRE WONDED -

25/5A

----- 03

6 wattmeter UPF 600V/10A 01

Page | 43


Obversation table:- s.no I(a) V(v) W(w) Real power

Procedure: 1. Connect the circuit as per the circuit diagram. 2. Before switch ON the supply make sure the rheostats are connected to the

fixed contacts. 3. Apply the capacitive load in steps of 1A to till 5A. 4. Note down the corresponding readings of wattmeter and ammaeter. 5. Tabulate the readings and measure the active power.


Real Power(w)= √3VIcosØ

Result:

Page | 44


11.CT TESTING USING MUTUAL INDUCTOR Aim:- To measure percentage ratio error and phase angle of given ct by null method . Apparatus required:-

s.no Apparatus Range Type Quantity 1 Ct test set -- -- 01 2 Variable current source -- -- 01 3 Standard CT -- -- 01 4 ‘X’CT -- -- 01 5 Burden box 5A,1A -- 01 6 Connecting wires -- -- As per

required

Procedure:-

1.connect the secondary’s of the “standard CT” at the terminals marked “STD” and “X” respectively. 2. connect the burden on secondary of the standard CT on which characteristics of the same are known at the terminals ”BURDEN” normally these are shorted. 3.connect the burden at which the “X” CT is to be tested at the terminals. 4.Burden. 5.Connect the 3 pin plug top to the mains(230+10%,50HZ). 6.Put the “1A-5A” switch at the required position. 7.ON the “Power-ON”switch.The %current meter will display “00”. 8.Turn the sensitivity knob in anticlockwise direction to bring it at minimum sensitivity position. 9.connect the primaries of “standard” transformer and”X” transformer of same current ratio in series to inject the same current in primary from the current source. 10.Increase the current up to 10%.In case reverse polarity is found, interchange the connection of any one of the CT. 11. Increase the sensitivity by turning sensitivity knob in clockwise direction and adjust “ratio error” and “phase angle error” knobs with proper selection of

Page | 45

MIST-ELECTRICAL MEASUREMENTS LAB MANUAL “Multiplier” switch ,”+/-’’ switch and “LEAD-LAG” switch to bring “Null detector” pointer towards zero. 12.The exact balance will be obtained by obtaining null with sensitivity knob in such a position that one division of each dial is discriminated by the null detector. It is not desirable to test or discriminate balance at higher sensitivity. 13. Adjust various percentage of primary current and obtain the reading at desired burdens.

Page | 46

OBSERVATION TABLES:- s.no Accuacy

class Percentage current (ratio)error at percentage of raged current

Phase displacement in minutes at percentage of rated current

Precautions: 1. There should not be any loose connections.

2. Meter readings should not be exceeded beyond their Ratings

3. Observe the ammeter reading. Apply the voltage slowly So that the current is within the limited range of ammeters

4. Handle the Bridge carefully. Result:-

Page | 47


12.PT TESTING BY NULL METHOD AIM:- Study of testing of potential transformer by using null methods. Apparatus required:-

s.no Apparatus Range Type Quantity 1 Single phase auto transformer 10A -- 01 2 voltmeter 0-300V MI 01 3 Ammeter 0-10A MI 01 4 Ac galvanometer AC 01 5 Rheostat 50Ω,2A -- 01 6 Rheostat 150Ω,5A -- 01 7 Mutual inductance 0.6Mh -- 01 8 Capacitor 2.5mfd/440V AC 01 9 Potential transformer 230v/230v -- 01

Procedure:- 1.connect the circuit as oer the diagram.

2.Switch on the supply and increase the voltage to the primary winding of PT by varying auto transformer.

3. Note down the readings.

4. Now adjust rheostat(r)such that galvanometer reads zero(null deflection)

5.Note down the readings.

6.bring back auto transformer to its initial position and switch off the supply.

Page | 48

Page | 49

OBSERVATION TABLE:-

S.no Applied input voltage to primary winding of PT in volts

Measured output voltage at secondary winding of PT in volts

Ratio of PT

1

2


PRECAUTIONS:-

1.All connections should be tight and right and as per the circuit diagram. 2.proper range of meter should be selected. 3.Ammeter should always be connected in serier and voltmeter in parallel with the circuit. Result:-

Page | 50


13.LVDT AND CAPACITANCE PICKUP

Aim:- To measure the displacement in the form of percentage error . Apparatus :- s.no Appataus name Quantity 1 LVDT kit 1 2 Capacitance pickup kit 1 3 Connecting wires As requried Circuit diagram:-

Page | 51

PROCEDURE:-

1. Connect the power supply chord at the rear panel to the 230V ,50Hz supply switch on the instrument by pressing down the toggle switch . the display glow to indicate the instrument is ON.\

2. Allow the instrument in ON position for 10 minutes for intial ware-up. 3. Rotate the micrometer till reads 20.0. 4. Adjust the CAL potentiometer at the front panel so that the display reads 10.0. 5. Rotates the core of micrometer till micrometer reads 10.0 and adjust the ZERO

potentiometer till the display reads 00.0. 6. Rotates back the micrometer core upto 20.0 and adjust once again CAL

potentiometer till the display reads 10.0 . Now the instrument is calibrated for +/-10.0mm range. As the core of LVDT moves the display reads the displacement in mm.

Page | 52

7. Rotate the core of the micrometer in steps of 1 or 2 mm and tabulate the readings.The micrometer will show the exact displacement given to the LVDT core the display will reads the displacement sensed by the LVDT.Tabulate the readings and plot the graph actual V/s indicator readings.

OBVERSATION TABLE:- s.no Actual

micrometer(mm) Indicator LVDT (mm)

Error % error

Result:-

14.Strain Guage AIM:- To calibrate the strain measurement resistance using strain measurement trainer. Apparatus:-

Sl. No.

Description

Type

Range

Quantity

1

Strain guage

cantilever beam

--

----

01

2

Strain

measurement trainer

--

--

01

Page | 53

3

Weights

1kg-1000kg

01

4

Connecting

wires

As required

Procedure:

1.check connections made and switch on the instrument by toggle switch at the back of the box the display glows to indicate the instrument is ON.

2.Allow instrument in on position for 10 minutes for initial warm up

3.Adjust zero potentiometer on the panel till the displayreads 000.

4.Apply load of 1kg on cantilever beam and adjust the cal potentiometer till display reads 377 micro strain remove weights the display shuld come to zero incase of any variation adjust the zeropot again and repeat the procedure again. Now the instrument is calibrated to read micro strain.

5.Apply load on the sensor using the loading arrangement provided in steps of 100g to 1kg.

6.The instrument display exact microstrain strained by the cantilever beam

7.Note the readings in the tabular column.percentage eroor in the reading hystresis

and accuracy of the instrument can be calculated by comparing with the theoretical values.

Calculation for cantilever:

S=(6Pl)/(BT2E)

P=Load applied in kg (1kg)

Page | 54

L=Effective length of beam in cms(22cms)

B=Width of beam

T=Thickness of beam (0.25cms)

E=Young modulus (2x106

S=Micro strain

Microstrain for above can be calculated

S=6x1x22/2.8x(0.25) 2 x2x 106

S=3.77X 10-4

S=377 Micro strain

Tabular colomn:

S.no. W(g) Indicate readings (ms)

Actual reading(ms) S=(6Pl)/(BT2E)

Error in% (%E)

Page | 55

Result:


15.MEASUREMENT OF TURNS RATIO OF A TRANSFORMER USING AC BRIDGE

AIM:-

Measurement of turn ratio of a transformer using ac bridge

Page | 56

Apparatus required:

Sl. No.

Description

Type

Range

Quantity

1

Transformer turn ratio kit

-

-

01

2

patch cards

-----

-----

As required

Procedure:

1.connect the as per the circuit diagram.

2.connect at 0 voltage and note down the unknown voltage .

3.connect 10 volts note down the unknown voltage.

4.Repeat above procedure up to 14 volts and note down the unknown voltage

Page | 57

Precautions:

1. There should not be any loose connections. 2. Meter readings should not be exceeded beyond their ratings. 3. Readings of the meters must be taking without parallax error.

FORMULA:-

% Deviation=measured turn ratio-expected turn ratio/expected turns ratio *100

Page | 58


OBSERVATION TABLE:-

s.no Known voltage Unknown voltage

Result:-

Page | 59


16.CT TESTING AIM:- To determine the ratio and phase angle over a given CT for different primary current using standard CT.

Apparatus required:- s.no Apparatus name Range Type Quantity 1 Current injection limit 25A --- 1

2 Phase stifting transformer

-- 1

3 Standard CT 25A/1.5A -- 1

4 Test CT 50A/10A -- 1

5 Wattmeter 300V,5A UPF 1

6 Wattmeter 300V,1A,0.2 pf or 300V,0.25A,0.2 pf

LPF 1

7 Ammter 0-5A MI 1

8 voltmeter 0-300V MI 1

Page | 60

MIST-ELECTRICAL MEASUREMENTS LAB MANUAL Procedure:-

1. Connect the circuit as per the circuit diagram. 2. Adjust the primary current to 20A secondary current will be about 5A for the normal ratio of

5. 3. Adjust the phase shifter is in phase with Js.The voltmeter and ammeter readings IS &V. 4. Adjust now phase shifter such that W1 reads zero.This ensures that ‘V’ is in quadrature with

IS.Note W2 check that voltmeter readings is same as in preious case other wise adjust ‘V’ to previous for IP=20A; 5A&10A note the values.

OBSERVATION TABLE:-

s.no Voltmeter (volts)

IP IS UPF W1

LPF W2

Phase shift angle

Phase angle error

Ratio error


Phase angle error β= tan -1(w1/w1-w2)+θ

Phase angle error=0

Ratio error=IP/IS

Precautions:

1. Applied voltage to the perious coil of the wattmeter should be kept constant.

Result:-

Page | 61


17..MEASUREMENT OF EARTH RESISTANCE

Aim : Electrical equipment at all voltage levels must be earthed i.e. connected directly to an electrodedriven or buried in the ground. The resistance between the earth electrodes is critical to the safety of equipment and personnel. Usually it must be less than 100 ohms. This is not always possible because of the high resistivity of some earthy materials. Measuring the earth resistanceis to be done the fall-of-potential method EQUIPMENT and PARTS LIST: 1.Digital earth resistance tester . 2.Earthing rods. 3.Auxiliary earth associated with tester 4.Cables associated with tester

Page | 62

Page | 63

PROCEDURE:

1.For each earthling electrodes perform the following: 2.Fit an existing earth electrode into the ground to be measured 3.Connect the earth to be measured X and auxiliary earth Y and Z to the corresponding terminalsof the tester. 4.Select rang of ohm as appropriate. 5.On the power of the tester. 6.For each distance between Y and X, press the push button control, read the displayed resistanceand then turn off the tester. 7.Tabulate the resistance values as shown in table 1 8. Note: All distance should be taken in straight line direction. 9.Joint the two earthling electrodes and then repeat the procedures. 10.Plot the results of on an graph paper.

observation table:-

Measureing result s.no Earthing plate Distance X-Y

(m) 0 0.5 1

Result:-

Page | 64


18.Measurment of insulation resistance Aim:-Measurment of insulation resistance EQUIPMENT and PARTS LIST: 1.Digital insulation resistance tester . 2.Cables associated with tester Procedure:-:-

1.You have seen that good insulation has high resistance; poor insulation, relatively low

resistance. The actual resistance value

2.s can be higher or lower, depending upon such factors as the temperature or moisture

content of the insulation (resistance decreases in temperature or moisture). With a little record-

keeping and common sense, however, you can get a good picture of the insulation condition

from values that are only relative.

3.The Megger insulation tester such as a Megger or a small, portable instrument that gives you

a direct reading of insulation resistance in ohms or megohms. For good insulation, the

resistance usually reads in the megohm range.

4.The Megger insulation tester is essentially a high-range resistance meter (ohmmeter) with a

built-in direct-current generator. This meter is of special construction with both current and

voltage coils, enabling true ohms to be read directly, independent of the actual voltage applied.

This method is nondestructive; that is, it does not cause deterioration of the insulation.

5.The generator can be hand-cranked or line-operated to develop a high DC voltage which

causes a small current through and over surfaces of the insulation being tested

Page | 65

6.. This current (usually at an applied voltage of 500 volts or more) is measured by the

ohmmeter .

7.which has an indicating scale. typical scale, which reads increasing resistance values from

left up to infinity, or a resistance too high to be measured.

Observation table:-

s.no Insulation resistance 1

Result:-

Date post:	18-Dec-2021
Category:	Documents
Upload:	others
View:	9 times
Download:	0 times

MAHAVEER INSTITUTE OF SCIENCE & TECHNOLOGY

Documents