Calibration Of Single Phase Energy Meter 102t6a

CALIBRATION OF SINGLE PHASE ENERGY METER BY DIRECT LOADING METHOD AIM: To calibrate the given energy meter by direct loading method APPARATUS: S.No

Equipment

Range

Type

1

Variac,single phase

10 A

AC

2

Voltmeter

300 V

AC

3

Ammeter

0-10A

AC

4

Rheostat

5

Wattmeter

LPF

AC

6

Single phase energy meter

10A

AC

Quantity

AC

THEORY: The calibration of energy meter may become inaccurate during its vigorous use due to various reasons. It is necessary to calibrate the meter to determine the amount of error i.e. its reading so that same meter can be used for correct measurement of energy. In this method precision grade indicating instruments are used as reference standard. These indicating instruments are connected in the circuit of meter under test. The current and voltages are held constant during the test. The numbers of revolutions made by the test are recorded. The time taken is also measured. Energy recorded by meter under test = RX / KX kWh. Energy computed from the readings of the indicating instrument = kW × t Where RX = number of revolutions made by disc of meter under test. KX = number of revolutions per kWh for meter under test,

kW = power in kilowatt as computed from readings f indicating instruments t = time in hours. Percentage Error

=

(RX / KX - kW × t) -------------------------

X 100

kW × t Before conducting any of these tests on a watt hour meter its potential circuit must be connected to the supply for one hour in order to enable the self heating of the potential coil to stabilize. CIRCUIT DIAGRAM:

figure:1 PROECEDURE: 1. Keep the Autotransformer at zero position. 2. Make connections as per the Circuit diagram shown below. 3. Switch on the 230 VAC, 50 Hz. power supply. 4. Increase the input voltage gradually by rotating the Auto transformer in clockwise direction. 5. Adjust the load rheostat so that sufficient current flows in the circuit. Please note that the current should be less then 4A. 6. Note down the Voltmeter, Ammeter, Wattmeter and power factor meter readings for different Voltages as per the tabular column. 7. Note down the time (by using stop watch) for rotating the disc of the Energy Meter for 10 times. Find out the percentage error by using above equations.

TABULAR COLUMN S. No.

Time

Voltage

Current

R = No of

(V)

(I)

revolutions (t) in of the disc

hours

Energy meter reading in KWh= No. revolution (R)/meter constant (K)

RESULT:

Wattmeter Reading in kW × t

% Error

CALIBRATION OF ENERGY METER BY PHANTOM LOADING AIM: To calibrate a given single phase energy meter by phantom loading. APPARATUS:

S.NO

Equipment

Range

Type

Variac, single

2 A, 0-

1

phase

230V

2

Voltmeter

0-300V

AC

3

Ammeter

0-10A

AC

4

Rheostat

5

Wattmeter

Quantity

Single Phase 6

Energy Meter

300V, 10A

THEORY: The calibration of energy meter may become inaccurate during its vigorous use due to various reasons. It is necessary to calibrate the meter to determine the amount of error i.e. its reading so that same meter can be used for correct measurement of energy. In this method precision grade indicating instruments are used as reference standard. These indicating instruments are connected in the circuit of meter under test. The current and voltages are held constant during the test. The numbers of revolutions made by the test are recorded. The time taken is also measured. Energy recorded by meter under test = RX / KX kWh. Energy computed from the readings of the indicating instrument = kW × t Where RX = number of revolutions made by disc of meter under test. KX = number of revolutions per kWh for meter under test,

kW = power in kilowatt as computed from readings f indicating instruments t = time in hours. Percentage Error

= (RX / KX - kW × t) -------------------------

X 100

kW × t Before conducting any of these tests on a watt hour meter its potential circuit must be connected to the supply for one hour in order to enable the self heating of the potential coil to stabilize. CIRCUIT DIAGRAM:

PROCEDURE

1. Keep the Autotransformer at zero position. 2. Make connections as per the Circuit diagram shown below. 3. Switch on the 230 VAC, 50 Hz. power supply. 4. Increase the input voltage gradually by rotating the Auto transformer

in clockwise direction. 5. Adjust the load rheostat so that sufficient current flows in the circuit. Please note that the current should be less then 4A. 6. Note down the Voltmeter, Ammeter, Wattmeter and power factor meter readings for different voltages as per the tabular column. 7. Note down the time (by using stop watch) for rotating the disc of the Energy Meter for 10 times. 8. Find out the percentage error by using above equations.

TABULAR COLUMN: S. No.

Time (t) in hours

Voltage

Current

R = No of

Energy meter reading

(V)

(I)

revolutions

in KWh= No.

of the disc

revolution (R)/meter constant (K)

RESULT

Expt No:

CALIBRATION OF SINGLE PHASE ENERGY METER

Date:

USING PHASE SHIFTING TRANSFORMER

AIM To calibrate the given single phase energy meter at unity and other power factors and to draw the calibration curve..

APPARATUS REQUIRED S.No

Apparatus Name

Type

1

Single phase energy meter

Induction type

Range

Qty 1

300 V; 10A, UPF

1

2

Standard wattmeter

3

Voltmeter

MI

(0-300) V

1

4

Ammeter

MI

(0-10) A

1

5

Lamp Load Phase Shifting transformer

230 V, 5 Kw

1

6

1

Single phase auto

7.

230/(0-270 V

transformer

8

Stop watch

9

Connecting wires

FORMULAE Energy meter specification rev/kwh= True energy (Pt) = (Power  Time ) / 36001000 Measured energy = n 750

, n  Number of revolutions

% Error = Measured  True 100  True

1

THEORY The energy meter is an integrated type of instrument where the speed of rotation of the aluminum disc is directly proportional to power consumed and the number of revolution per minute is proportional to the energy consumed by the load. The ratings associated with the energy meter are 1. 2. 3. 4.

Voltage rating Current rating Frequency rating Meter constants The driving system of the meter provides the rotational torque for the moving system, which in turn activates the energy registration system for reading purposes. The energy meter is operated on induction principle, in which the eddy current induced in the aluminum disc interacts with the main field and creates the driving torque. This system employs phantom loading. Here, the phase shifting transformer to supply the voltage of varying power factor to the potential coil of energy meter. The system phase supply is used to supply current of energy required value to the current coil of energy meter. Thus energy meter is tested under various power factor loads without applying any actual load. This is called phantom loading.

PROCEDURE 1. Give the connections as per the circuit diagram. 2. Switch on the three phase supply through phase shifting transformer. Also switch on the single phase supply through autotransformer. The autotransformer should be kept in minimum position before switching on. 3. Set the 5A current in ammeter with the help of auto transformer. 4. Now note down the voltage, current and power from the respective meters. Also note the time required for the disc to rotate hundred times. 5. Repeat step 3 for various power factors The power factor is set with the help of phase shifting transformer. 6. Tabulate the readings and do the necessary calculations.

Circuit Diagram

Sl No

Mod el Calc ulati on

Wattmeter Power Observed Actual Reading Reading (Watts) (Watts)

Time for n rev Seconds

Power Factor

Measured Energy KwH

True Energy KwH

% Error

CALIBRATION OF SINGLE PHASE DIGITAL ENERGY METER BY DIRECT LOADING METHOD AIM: To calibrate the given energy meter by direct loading method APPARATUS: S.No

Equipment

Range

Type

1

Variac,single phase

10 A

AC

2

Voltmeter

300 V

AC

3

Ammeter

0-10A

AC

4

Rheostat

5

Wattmeter

LPF

AC

6

Single phase energy meter

10A

AC

Quantity

AC

THEORY: RES ULT:

The calibration of energy meter may become inaccurate during its vigorous use due to various reasons. It is necessary to calibrate the meter to determine the amount of error i.e. its reading so that same meter can be used for correct measurement of energy. In this method precision grade indicating instruments are used as reference standard. These indicating instruments are connected in the circuit of meter under test. The current and voltages are held constant during the test. The numbers of revolutions made by the test are recorded. The time taken is also measured. Energy recorded by meter under test = RX / KX kWh. Energy computed from the readings of the indicating instrument = kW × t Where RX = number of impulse of meter under test. KX = number of revolutions per kWh for meter under test,

Percentage Error kW =

=

(RX / KX - kW × t) -------------------------

power

X 100

kW × t

kilowatt as Before conducting any of these tests on a watt hour meter its potential circuit must be connected to the supply for one hour in order to enable the self heating of the computed potential coil to stabilize. from CIRCUIT readings f DIAGRAM: indicating instrument s t = time in

PROECEDURE: 1. Keep the Autotransformer at zero position. 2. Make connections as per the Circuit diagram shown below. 3. Switch on the 230 VAC, 50 Hz. power supply. 4. Increase the input voltage gradually by rotating the Auto transformer in clockwise direction. 5. Adjust the load rheostat so that sufficient current flows in the circuit. Please note that the current should be less then 4A.

6. N

Wattmeter and power factor meter readings for different Voltages as per

o

the tabular column.

t

7. Note down the time (by using stop watch) for rotating the disc of the Energy Meter for 10 times. Find out the percentage error by using above

e

equations. d o w TABULAR COLUMN n t

S. No.

Current

R = No of

(V)

(I)

revolutions (t) in of the disc

h

o l t m e t e r

m m e t e r ,

reading in KWh= No. revolution (K)

V

A

hours

Energy meter

(R)/meter constant

e

,

Time

Voltage

RESULT:

Wattmeter Reading in kW × t

% Error

MEASUREMENT OF RESISTANCE USING WHEATSTONE BRIDGE AIM To measure the given medium resistance using Wheatstone bridge.

Apparatus Required Sl.No.

Apparatus

Range

Quantity

1

Wheatstone bridge kit

--

1

2

Unknown resistance

--

1

3

Galvanometer

--

1

4

Patch card

--

6

Theory It is used for the measurement of medium resistances. Very high degrees of accuracy can be achieved with the Wheatstone bridge. It has four resistive arms, consisting of resistances R1, R2, R3 and R4 together with a battery source and a null detector usually a galvanometer or other sensitive current meter. The current through the galvanometer depends on the potential difference between points C and D. The bridge is said to be balanced when there is no current through the galvanometer or when the potential difference across the galvanometer is zero. For bridge balance we can write, I1 R 1 = I2 R 2 For galvanometer current to be zero, the following conditions also exist:

(1)

Procedure 

The unknown resistance is connected to the kit. Ratio arm is set to some value.



By adjusting the resistance R1 the galvanometer is made to indicate null position or zero, indicating balanced condition.



The values of resistance are noted using multimeter.



The unknown resistance is calculated from these values. 

WHEASTONE BRIDGE METHOD



 

Tabulation 

S r.No.  U nit



Value marked  

R2





Rm









 Unknown resistance Rx  

   

1 2 3 4



1000



1000



1000

 1000

























  

 MODEL CALCULATION              RESULT               