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ELECTRICAL MEASUREMENT LAB (3039) DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

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ELECTRICAL MEASUREMENT

LAB (3039)

DEPARTMENT OF ELECTRICAL & ELECTRONICS

ENGINEERING

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 2

TOPICS PAGE NO.

VERIFICATION OF KCL AND KVL. 01

THREE AMMETER METHOD. 03

THREE VOLT METER METHOD. 06

THREE PHASE POWER MEASUREMENT. 09

CALIBRATION OF WATTMETER BY VOLT METER

AND AMMETER. 12

CALIBRATION OF ENERGY METER BY DIRECT

LOADING 14

CALIBRATION OF WATTMETER BY PHANTOM

LOADING 16

MEASUREMENT OF INDUCTANCE 19

RLC SERIES CIRCUIT 22

CALIBRATION OF ENERGY METER BY PHANTOM

LOADING 24

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 1

VERIFICATION OF KCL&KVL

AIM

To verify KCL&KVL in dc circuit.

CIRCUIT DIAGRAM

APPARATUS REQUIRED

THEORY

𝑲𝑰𝑹𝑪𝑯𝑶𝑭𝑭’𝒔 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 𝒍𝒂𝒘(𝑲𝑪𝑳)

𝑰𝒕 𝒔𝒕𝒂𝒕𝒆𝒔 𝒕𝒉𝒂𝒕 𝒂𝒍𝒈𝒆𝒃𝒓𝒂𝒊𝒄 𝒔𝒖𝒎 𝒐𝒇 𝒕𝒉𝒆 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 𝒎𝒆𝒆𝒕𝒊𝒏𝒈 𝒂𝒕 𝒂𝒏𝒚 𝒋𝒖𝒏𝒄𝒕𝒊𝒐𝒏 𝒊𝒔 𝒛𝒆𝒓𝒐.

Ʃ𝑰 = 𝟎

Sl No Apparatus Specification Quantity

1

2

3

4

Autotransformer

Voltmeter

Ammeter

Rheostat

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 2

𝑲𝑰𝑹𝑪𝑯𝑶𝑭𝑭’𝒔 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝒍𝒂𝒘(𝑲𝒗𝑳)

𝑰𝒕 𝒔𝒕𝒂𝒕𝒆𝒔 𝒕𝒉𝒂𝒕 𝒊𝒏 𝒂𝒄𝒍𝒐𝒔𝒆𝒅 𝒎𝒆𝒔𝒉,𝒂𝒍𝒈𝒆𝒃𝒓𝒂𝒊𝒄 𝒔𝒖𝒎 𝒐𝒇 𝒕𝒉𝒆 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝒅𝒓𝒐𝒑 𝒊𝒏 𝒓𝒆𝒔𝒊𝒔𝒕𝒐𝒓𝒔 𝒂𝒏𝒅 𝒆𝒎𝒇’𝒔 𝒆𝒒𝒖𝒂𝒍 𝒕𝒐 𝒛𝒆𝒓𝒐

𝑰𝒆,Ʃ𝑰𝑹 + Ʃ𝑬𝑴𝑭𝒔 = 𝟎

PROCEDURE

1. Connect the circuit as in the connection diagram.

2. Check the connections and correct the mistake if any.

3. Switch on the supply

4. Vary the autotransformer dor different readings.

5. Take all meter readings& tabulate

6. Verify kcl & kvl.

TABULATION

Sl no V1 V2 V3 V2+V3 I1 I2 I3 I2+I3

RESULT

Verified Kirchhoff’s current law &voltage law

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 3

MEASUREMENT OF SINGLE PHASE POWER AND POWER FACTOR

USING THREE AMMETERS.

AIM

To measure the power and power factor of the given R-L circuit using three Ammeters.

(Without using Wattmeter)

CIRCUIT DIAGRAM

APPARATUS REQUIRED

Sl No Apparatus Specification Quantity

1

2

3

4

5

Ammeter

Voltmeter

Rheostat

Autotransformer

Transformer

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 4

THEORY

Power factor is the cosine of the angle between phase voltage and current. The maximum value of power

factor is unity, i.e. for pure resistive load and minimum value is zero.ie for pure inductive load (lagging) or pure

capacitive load (leading).

For an R-L circuit, the current lags voltage by certain angle, which is called the power factor angle ø.

The vector diagram is shown in figure. Voltage V is taken as the reference, I2is in phase with V (since

current through pure resistance- in phase with V,), I3 lags behind V by angle ø, (since R-L circuit), I1 is the

vector sum of I2 and I3.

𝐼12 = (𝐼2 + 𝐼3𝐶𝑜𝑠ø)2 + ( 𝐼3𝑆𝑖𝑛ø)2

= 𝐼22 + 𝐼3

2𝐶𝑜𝑠2ø + 2𝐼2𝐼3𝐶𝑜𝑠ø + 𝐼32𝑆𝑖𝑛2 ø

= 𝐼22 + 𝐼3

2 + 2𝐼2𝐼3 𝐶𝑜𝑠ø

𝑃𝐹 = ( 𝐼12 − 𝐼2

2 − 𝐼32)/2𝐼2𝐼3

𝑊𝑒 𝑕𝑎𝑣𝑒 𝑉 = 𝐼2𝑅

𝑆𝑜, 𝑃𝑜𝑤𝑒𝑟 𝐶𝑜𝑛𝑠𝑢𝑚𝑒𝑑 𝑏𝑦 𝑡𝑕𝑒 𝑙𝑜𝑎𝑑 = 𝑉𝐼3𝐶𝑜𝑠ø

= 𝐼2𝑅 𝐼3 ( 𝐼12 − 𝐼2

2 − 𝐼32)/2𝐼2𝐼3

𝑃𝑜𝑤𝑒𝑟 = 𝑅

2 ( 𝐼1

2 − 𝐼22 − 𝐼3

2)

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 5

PROCEDURE:

1. Connect the circuit as in the connection diagram.

2. Check the connections and correct the mistake if any.

3. Switch on the supply

4. Adjust the auto transformer upto rated voltage of the load.

5. Adjust the load for different readings.

6. Calculate the results accordingly.

TABULATION

Sl No V/m

Reading-

Volts

I1

Amps

I2

Amps

I3

Amps

Power=

R/2(I12-I2

2-I3

2)

PF=

(I12-I2

2-I3

2)/2 I2I3

RESULT

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 6

MEASUREMENT OF SINGLE PHASE POWER AND POWER FACTOR

USING THREE VOLTMETERS.

AIM

To measure the power and power factor of the given R-L circuit using three voltmeters.

(Without using Wattmeter)

CIRCUIT DIAGRAM

APPARATUS REQUIRED

THEORY

Power

factor is the

cosine of

the angle

between phase voltage and current. The maximum value of power factor is unity, i.e. for pure resistive load and

minimum value is zero.ie for pure inductive load (lagging) or pure capacitive load (leading).

For an R-L circuit, the current lags voltage by certain angle, which is called the power factor angle ø.

Sl No Apparatus Specification Quantity

1

2

3

4

5

Ammeter

Voltmeter

Rheostat

Autotransformer

Transformer

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 7

The vector diagram is shown in figure. Current I is taken as the reference, V2 in phase with I ( since current

through pure resistance- in phase with V,), V3 Leads current I by angle ø, (since R-L circuit), V1 is the vector

sum of V2 and V3.

V12= (V2+V3Cosø)

2+ ( V3Sinø)

2

= V22+V3

2Cos

2ø+2V2V3Cosø+V3

2Sin

2 ø

= V22+V3

2+2 V2V3 Cosø

... PF=( V1

2-V2

2-V3

2)/2 V2V3

We have V2= IR

So, Power Consumed by the load= V3ICosø

= ( V12-V2

2-V3

2)/2 R

Power =( V12-V2

2-V3

2)/2 R

`

PROCEDURE:

1. Connect the circuit as in the connection diagram.

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 8

2. Check the connections and correct the mistake if any.

3. Switch on the supply

4. Adjust the auto transformer upto rated voltage of the load.

5. Adjust the load for different readings.

6. Calculate the results accordingly.

p

TABULATION

Sl No V/m

Reading-

Volts

V1

Amps

V2

Amps

V3

Amps

Power=

(V12-V2

2-V3

2)/2R

PF=

(V12-V2

2-

V32)/2V2V3

RESULT

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 9

MEASUREMENT OF THREE PHASE POWER AND POWER FACTOR USING

TWO WATTMETERS

AIM

To measure the input power and determine power factor of a balanced three phase load using two W/ms.

CIRCUIT DIAGRAM

APPARATUS REQUIRED

Sl No Apparatus Specification Quantity

1

2

3

4

5

Three phase autotransformer

Voltmeter

Ammeter

Wattmeter

Rheostat

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 10

THEORY:

𝑻𝒉𝒆 𝒇𝒐𝒍𝒍𝒐𝒘𝒊𝒏𝒈 𝒎𝒆𝒕𝒉𝒐𝒅𝒔 𝒂𝒓𝒆 𝒖𝒔𝒆𝒅 𝒇𝒐𝒓 𝒕𝒉𝒆 𝒎𝒆𝒂𝒔𝒖𝒓𝒆𝒎𝒆𝒏𝒕 𝒐𝒇 𝒕 𝒉𝒆𝒓𝒆 𝒑𝒉𝒂𝒔𝒆 𝒑𝒐𝒘𝒆𝒓.

𝟏. 𝑶𝒏𝒆 𝒘𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 𝒎𝒆𝒕𝒉𝒐𝒅 − 𝑭𝒐𝒓 𝒃𝒂𝒍𝒂𝒏𝒄𝒆𝒅 𝒍𝒐𝒂𝒅.

𝟐. 𝑻𝒘𝒐 𝑾𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 𝒎𝒆𝒕𝒉𝒐𝒅 – 𝑭𝒐𝒓 𝑩𝒂𝒍𝒂𝒏𝒄𝒆𝒅 / 𝑼𝒏𝒃𝒂𝒍𝒂𝒏𝒄𝒆𝒅 𝒍𝒐𝒂𝒅.

𝟑. 𝑻𝒉𝒓𝒆𝒆 𝒘𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 𝒎𝒆𝒕𝒉𝒐𝒅 − 𝑭𝒐𝒓 𝑩𝒂𝒍𝒂𝒏𝒄𝒆𝒅 / 𝑼𝒏𝒃𝒂𝒍𝒂𝒏𝒄𝒆𝒅 𝒍𝒐𝒂𝒅.

Two W/m Method: - (Balanced load)

𝑳𝒆𝒕 𝒕𝒉𝒆 𝒍𝒐𝒂𝒅 𝒃𝒆 𝒂 𝟑 ø 𝒃𝒂𝒍𝒂𝒏𝒄𝒆𝒅 𝒔𝒕𝒂𝒓 𝒄𝒐𝒏𝒏𝒆𝒄𝒕𝒆𝒅 𝒐𝒏𝒆.

𝑳𝒐𝒂𝒅 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 𝒕𝒉𝒓𝒐𝒖𝒈𝒉 𝒘𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 𝑾𝟏 𝒊𝒔 𝑰 𝑹 𝒂𝒏𝒅. 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝒂𝒄𝒓𝒐𝒔𝒔 𝒕𝒉𝒆 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝒄𝒐𝒊𝒍 𝒐𝒇 𝒕𝒉𝒆 𝑾

/𝒎 𝑾𝟏 𝒊𝒔 𝑽𝑹𝒀 = 𝑽𝑹 − 𝑽𝒀

𝑹𝒆𝒂𝒅𝒊𝒏𝒈 𝒐𝒇 𝒘𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 𝟏 = 𝑽𝑹𝒀𝑰 𝑹𝑪𝒐𝒔 (𝟑𝟎 + ø) = 𝑽𝑳 𝑰 𝑳𝑪𝒐𝒔 (𝟑𝟎 + ø)

𝑵𝒐𝒘 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 𝒕𝒉𝒓𝒐𝒖𝒈𝒉 𝒘𝒂𝒕𝒕𝒎𝒆𝒕𝒆𝒓 − 𝟐 = 𝑰𝑩

𝑷 𝑫 𝒂𝒄𝒓𝒐𝒔𝒔 𝑾𝟐 = 𝑽𝑩𝒀 = 𝑽𝑩 − 𝑽𝒀

𝑷𝒉𝒂𝒔𝒆 𝒅𝒊𝒇𝒇𝒆𝒓𝒆𝒏𝒄𝒆 𝒃𝒆𝒕𝒘𝒆𝒆𝒏 𝑰 𝑩𝒂𝒏𝒅 𝑽𝑩𝒀 𝒊𝒔 (𝟑𝟎 − ø)

𝑹𝒆𝒂𝒅𝒊𝒏𝒈 𝒐𝒇 𝑾𝟐 = 𝑽𝑩𝒀𝑰𝑩 𝑪𝒐𝒔(𝟑𝟎 − ø)

𝑺𝒊𝒏𝒄𝒆 𝒕𝒉𝒆 𝒍𝒐𝒂𝒅 𝒊𝒔 𝒃𝒂𝒍𝒂𝒏𝒄𝒆𝒅 𝑽𝑹𝒀 = 𝑽𝑩𝒀 = 𝑽𝑩𝑹 = 𝑽𝑳

𝑺𝒊𝒎𝒊𝒍𝒂𝒓𝒍𝒚 𝑰𝑹 = 𝑰𝒀 = 𝑰𝑩 = 𝑰𝑳

𝑇𝑕𝑒𝑛 𝑡𝑕𝑒 𝑠𝑢𝑚 𝑜𝑓 𝑤𝑎𝑡𝑡𝑚𝑒𝑡𝑒𝑟 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 𝑖𝑠 𝑡𝑕𝑒 𝑡𝑜𝑡𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑 𝑏𝑦 𝑡𝑕𝑒 3 ø 𝑙𝑜𝑎𝑑.

𝑾𝟏 + 𝑾𝟐 = 𝑽𝑳 𝑰𝑳 𝑪𝒐𝒔 (𝟑𝟎 − ø) + 𝑽𝑳 𝑰𝑳 𝑪𝒐𝒔 (𝟑𝟎 + ø)

= 𝑽𝑳 𝑰𝑳 [𝑪𝒐𝒔 (𝟑𝟎 − ø) + 𝑪𝒐𝒔 (𝟑𝟎 + ø)]

= 𝑽𝑳 𝑰𝑳𝟐 𝑪𝒐𝒔 𝟑𝟎 𝑪𝒐𝒔ø.

= 𝑽𝑳 𝑰𝑳 𝟐. 𝟑/𝟐.𝑪𝒐𝒔ø

= 𝟑 𝑽𝑳 𝑰𝑳𝑪𝒐𝒔ø. = 𝑬𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒇𝒐𝒓 𝒕𝒐𝒕𝒂𝒍 𝒑𝒐𝒘𝒆𝒓 𝒊𝒏 𝒕𝒉𝒓𝒆𝒆 𝒑𝒉𝒂𝒔𝒆 𝒍𝒐𝒂𝒅.

𝑾𝟏 − 𝑾𝟐 = 𝑽𝑳 𝑰𝑳 𝑪𝒐𝒔 (𝟑𝟎 − ø) − 𝑽𝑳 𝑰𝑳 𝑪𝒐𝒔 (𝟑𝟎 + ø)

= 𝑽𝑳 𝑰𝑳 [𝑪𝒐𝒔 (𝟑𝟎 − ø) − 𝑪𝒐𝒔 (𝟑𝟎 + ø)]

= 𝑽𝑳 𝑰𝑳 𝟐. 𝑺𝒊𝒏 𝟑𝟎.𝑺𝒊𝒏ø

= 𝟐. 𝟏/𝟐. 𝑽𝑳 𝑰𝑳 . 𝑺𝒊𝒏ø

= 𝑽𝑳 𝑰𝑳 . 𝑺𝒊𝒏ø

𝑾𝟏− 𝑾𝟐

𝑾𝟏+ 𝑾𝟐 =

𝑽𝑳 𝑰𝑳 .𝑺𝒊𝒏ø

3𝑽𝑳 𝑰𝑳𝑪𝒐𝒔ø =

1

3tan

= 𝐭𝐚𝐧−𝟏[ 𝟑(𝑾𝟏− 𝑾𝟐𝑾𝟏+ 𝑾𝟐

)]

𝑯𝒆𝒏𝒄𝒆 𝒑𝒐𝒘𝒆𝒓 𝒇𝒂𝒄𝒕𝒐𝒓 𝒄𝒐𝒔 𝒄𝒂𝒏 𝒃𝒆 𝒄𝒂𝒍𝒄𝒖𝒍𝒂𝒕𝒆𝒅.

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 11

PROCEDURE

1. Connections are made as shown in the circuit diagram

2. Keep the autotransformer at minimum position

3. Adjust the autotransformer till the voltmeter reads rated voltage of the load.

4. Take the corresponding v/m, a/m and w/m readings.

5. Adjustthe load for different readings

6. Tabulate the readings and calculate the power and power factor

TABULATION

Sl no V I W1 W2 W1+W2 W2-W1 𝑻𝒂𝒏

𝒄𝒐𝒔

RESULT:

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 12

CALIBRATION OF WATTMETER USING VOLTMETER AND AMMETER. AIM

To calibrate the given single phase wattmeter using standard voltmeter and ammeter. Draw the error curve.

CIRCUIT DIAGRAM

APPARATUS REQUIRED:-

THEORY

Calibration of wattmeter means standardizing of meter and finding out the error. A wattmeter is a device

that is constructed out of pressure coil and current coil. The pressure coil is connected in parallel with the

circuit, and current coil in series with the circuit. The current coil has low resistance connected in series with the

ammeter.

Sl No Apparatus Specification Quantity

1

2

3

4

Voltmeter

Ammeter

Wattmeter

Lamp load

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 13

There are Induction type (used in AC measurements only) and Dynamometer type wattmeter (used in

both AC & DC measurements).

𝑅𝑒𝑐𝑜𝑟𝑑𝑒𝑑 𝑝𝑜𝑤𝑒𝑟 = 𝑤𝑎𝑡𝑡𝑚𝑒𝑡𝑒𝑟 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 𝑥 𝑚𝑢𝑙𝑡𝑖𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 𝑜𝑓 𝑤𝑎𝑡𝑡𝑚𝑒𝑡𝑒𝑟.

𝑀𝑢𝑙𝑡𝑖𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟

= 𝑆𝑒𝑙𝑒𝑐𝑡𝑒𝑑 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑟𝑎𝑛𝑔𝑒 𝑜𝑓 𝑊/𝑚 𝑥 𝑆𝑒𝑙𝑒𝑐𝑡𝑒𝑑 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑟𝑎𝑛𝑔𝑒 𝑜𝑓 𝑤𝑎𝑡𝑡𝑚𝑒𝑡𝑒𝑟 𝑥 𝑃𝐹

𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 𝑜𝑛 𝑡𝑕𝑒 𝑑𝑖𝑎𝑙 𝑜𝑓 𝑤𝑎𝑡𝑡𝑚𝑒𝑡𝑒𝑟.

𝑇𝑟𝑢𝑒 𝑝𝑜𝑤𝑒𝑟 = 𝑉/𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 𝑥 𝐴/𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 ,

𝑠𝑖𝑛𝑐𝑒 𝑡𝑕𝑒 𝑙𝑜𝑎𝑑 𝑢𝑠𝑒𝑑 𝑖𝑠 𝑝𝑢𝑟𝑒𝑙𝑦 𝑟𝑒𝑠𝑖𝑠𝑡𝑖𝑣𝑒, 𝑖𝑡𝑠 𝑝𝑓 𝑖𝑠 𝑢𝑛𝑖𝑡𝑦.

%𝑒𝑟𝑟𝑜𝑟 =𝑟𝑒𝑐𝑜𝑟𝑑𝑒𝑑 𝑝𝑜𝑤𝑒𝑟 − 𝑡𝑟𝑢𝑒 𝑝𝑜𝑤𝑒𝑟

𝑟𝑒𝑐𝑜𝑟𝑑𝑒𝑑 𝑝𝑜𝑤𝑒𝑟× 100

PROCEDURE

1. Connect the circuit as shown in figure

2. Checked the connections and given the supply.

3. Adjust the auto transformer upto rated voltage of the meter to be tested

4. Varied the load and taken the corresponding readings. Up to the 120% of the rated current of the meter

to be tested.

5. Calculated the true power, recorded power and % error at the different loads.

6. Plotted the error curve.

TABULATION

RESULT

Sl

No 𝐴/ 𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔− 𝐴𝑚𝑝𝑠

𝑉/𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 −𝑉𝑜𝑙𝑡𝑠

𝑊/𝑚− 𝑊𝑎𝑡𝑡𝑠

𝑅𝑒𝑐. 𝑃𝑜𝑤𝑒𝑟 𝑊𝑎𝑡𝑡𝑠 𝑇𝑟𝑢𝑒 𝑝𝑜𝑤𝑒𝑟 𝑊𝑎𝑡𝑡𝑠

% 𝐸𝑟𝑟𝑜𝑟

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 14

ENERGY METER CALIBRATION BY DIRECT LOADING

AIM

To calibrate the energy meter by direct loading.

CIRCUIT DIAGRAM

APPARATUS REQUIRED

THEORY

The process of comparing of an instrument with standard or absolute instrument is called calibration.

The energy meter records the energy consumed in KWH. Let 𝑅𝑋 be the number of revolutions of the

disc. 𝐾𝑋 Is the revolution per KWH (meter constant).

Recorded energy=𝑅𝑋 𝐾𝑋 𝐾𝑊𝐻

Sl No Apparatus Specification Quantity

1

2

3

4

5

Voltmeter

Ammeter

Wattmeter

Lamp load

Energy meter

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 15

The true energy=𝑤/𝑚 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 ∗ 𝑡𝑖𝑚𝑒

%error= (𝑟𝑒𝑐𝑜𝑟𝑑𝑒𝑑 𝑒𝑛𝑒𝑟𝑔𝑦 − 𝑡𝑟𝑢𝑒 𝑒𝑛𝑒𝑟𝑔𝑦)/𝑡𝑟𝑢𝑒 𝑒𝑛𝑒𝑟𝑔𝑦 × 100

PROCEDURE

1. Connections are made as per the circuit diagram

2. Keep the autotransformer at minimum position and switch on the supply

3. Adjust the autotransformer to the rated voltage of the energy meter

4. Adjust the load to a suitable value and note the corresponding w/m reading and time taken for 5

revolution of energy meter disc

5. Repeat the step no 4 after increasing the load

6. Tabulate the readings and calculate the %error

OBSERVATION

Sl no v/m in

volt

A/m in

amps

No. of

rev

w/m in

watts

Time in

sec

True

energy

Actual

energy

%error

RESULT

Calibrated the given single phase energy meter by direct loading at UPF and plotted the error curve

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 16

CALIBRATION OF WATTMETER BY PHANTOM LOADING

AIM

To calibrate the given single phase wattmeter by phantom loading at UPF and at 0.5pf lag and plot the error

curve

CIRCIT DIAGRAM

……………….

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 17

APPARATUS REQUIRED:-

THEORY

When current rating of the meter under test is high, a test with actual loading arrangements involves

considerable waste of power. Phantom loading consists of supplying the pressure circuit with required

normal voltage and the current circuit from a low voltage supply. the total power required for testing the

meter with phantom loading is comparatively very small.

OBSERVATION

PF v/m A/m Indicating

reading

watts

Actual reading

watts

Percentage

error= 𝐼𝑅−𝐴𝑅

𝐴𝑅

UPF

0.5

LAG

PROCEDURE

At UPF

1. Connections are made as shown in diagram

2. The rated voltage applied across pressure coil

3. Keep the autotransformer at its minimum position and switch on the power supply.

4. Adjust the autotransformer for various values of current from minimum to maximum

5. Take all meter readings and calculate the percentage error

Sl No Apparatus Specification Quantity

1

2

3

4

Voltmeter

Ammeter

Wattmeter

Lamp load

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 18

6. Plot error curve

At 0.5pf lag

1. Connect the pressure coil across N&Y and CC in R phase

2. Repeat the same procedure mentioned above

3. Plot the error curve

RESULT

The given single phase wattmeter is calibrated at UPF and 0.5 lag by phantom loading

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 19

MEASUREMENT OF INDUCTANCE

AIM

To measure the inductance and power factor of the given coil.

CIRCUIT DIAGRAM

MEASUREMENT OF RESISTANCE OF THE COIL

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 20

APPARATUS REQUIRED:-

CIRCUIT TO FIND RESISTANCE OF THE COIL

THEORY

Inductance is the property of a circuit or a component to oppose the change in current through it. An

induction coil has a small resistance and an inductive reactance.

XL = 𝒁𝟐 − 𝑹𝟐

But XL=2πfL

I.e., L= 𝑋𝐿

2𝜋𝑓

Power factor of the coil=𝑃 𝑉𝐼

PROCEDURE

1. Connections are made as shown in diagram

2. Keep the autotransformer in the minimum position and switch on the supply

3. Adjust the autotransformer into rated voltage

4. Note all meter readings

5. Tabulate the reading and calculate the inductance and pf of the coil

PROCEDURE FOR FINDING RESISTANCE OF THE COIL

1. Connections are made as shown in diagram

2. Keep the autotransformer in the minimum position and switch on the supply

3. Adjust the autotransformer for different ammeter readings up to the rated current of the coil

4. Note all meter readings

5. Tabulate the reading and calculate the resistance of the coil

Sl No Apparatus Specification Quantity

1

2

3

4

Voltmeter

Ammeter

Wattmeter

Inductive coil

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 21

TABULATIONS

Sl no Volt

meter

reading

in volt

Ammeter

reading

in

ampere

Wattmeter

reading P

in watts

Z=V/I

ohm

R ohm

XL

= 𝑍2 − 𝑅2

ohm

L=

XL 2𝜋𝑓 Henry

Pf= 𝑃

𝑉𝐼

RESULT

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 22

RLC SERIES CIRCUIT

AIM

To determine the Resistance, Reactance and impedance of RLC series circuit.

CIRCUIT DIAGRAM

APPARATUS REQUIRED

SI No Instrument specification QUT

1

2

3

4

5

6

AMMETER

VOLTMETER

RHEOSTAT

CHOKE

CAPACITOR

AUTOTRANSFORMER

1NO

1 EACH

1 NO

1 NO

1NO

1 NO

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 23

THEORY

In the RLC circuit , let I be the current through the circuit . let V be the applied voltage and VR,VL,and

VL be the voltage across resistor , inductor and capacitor respectively.

R=(VR / I)

XL=(VL/I)

XC=VC/I

V=IZ

=I (𝑅2+(XL-XC)

2)

Z is called impedance of the circuit.

Power factor cos ∅=(W/VI)=R/Z

PROCEDURE

1. Connections are given as per the diagram.

2. The experiment is started by keeping the autotransformer at minimum position.

3. Then adjust the autotransformer so as to vary the input voltage so the current trough the circuit also

changed.

4. All meter readings are to be takent at this condition.

5. Then repeat the procedure by changing autotransformer.

6. Take voltage and current in each case.

7. Calculate all parameters from this reading

TABULATION

SI

no

V

VOLT

I

AMPS

W

WATT

VR

VOLT

VL

VOLT

VC

VOLT

XL

OHM

XC

OHM

R

OHM

RESULT

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 24

CALIBRATION OF ENERGY METER BY PHANTOM LOADING

AIM

To calibrate the given single phase wattmeter by phantom loading at UPF and at 0.5pf.

CIRCUIT DIAGRAM

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 25

APPARATUS REQUIRED:-

THEORY

When current rating of the meter under test is high, a test with actual loading arrangements involves

considerable waste of power. Phantom loading consists of supplying the pressure circuit with required

normal voltage and the current circuit from a low voltage supply. the total power required for testing the

meter with phantom loading is comparatively very small.

Recorded reading=5

𝑡X

3600

𝑁KWH

Actual reading=power X time KWH

PROCEDURE

At UPF

1. Connections are made as shown in diagram

2. The rated voltage applied across pressure coil

3. Keep the autotransformer at its minimum position and switch on the power supply.

4. Adjust the autotransformer for various values of current from minimum to maximum

5. Take all meter readings and time taken for 5revolution of E/M disc

6. Plot error curve

At 0.5pf lag

1. Connect the pressure coil across N&Y and CC in R phase

2. Repeat the same procedure mentioned above

3. Plot the error curve

Sl No Apparatus Specification Quantity

1

2

3

4

Voltmeter

Ammeter

Wattmeter

Lamp load

ELECTRICAL MEASUREMENT LAB DEPARTMENT OF EEE

MA’DIN Polytechnic college 26

TABULATION

PF v/m A/m Time for

5rev of

E/M disc

Recorded

Energy=

5

𝑡×

3600

𝑁

KWH

Actual

Energy=

𝑉𝐼 cos ∅/1000

Error

𝑅𝑃 − 𝐴𝑃

%error= 𝑅𝑃 − 𝐴𝑃

𝑅𝑃

UPF

0.5

LAG

RESULT

The given single phase energy meter is calibrated at UPF and 0.5 lag by phantom loading