Page 97 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 40 : To measure the Electrical energy in single

Ph. load

Objectives

At the end of this exercise you shall be able to:
• check & identify the terminals and parts of 1 Ph. Energy meter, check meter constant
• connect the energy meter to 1 Ph. Supply with lighting load
• measure the energy recorded in energy meter for given load and time.

Requirements

Tools/Equipments/Instruments

• Combination Plier 165mm, • Lamp load 1 Ph. 230V, 5KW -1 No.
insulated -1 No. • Stop watch -1 No.
• Screw Driver 150mm, -1 No. Materials/Components
• Neon Tester 75mm, 500 V -1 No.
• Electrician knife insulated -1 No. • PVC copper wire 1.5 sq.mm -2 meter.
• KWH meter 1 Ph. 240V, 10A -1 No. • Test lamp 100 W, 230V -1 No.
• Voltmeter MC, 300 V -1 No. • DPST switch 16 A, 230 V -1 No.
• Ammeter MI, 10 A -1 No.
• Multi meter Digital, 3 digit -1 No.
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Procedure

TASK 1: Check & identify the terminals, meter constant of Energy meter
1 Draw the circuit diagram of measurement of electrical energy in 1 Ph. load
2 Check the 1 Ph. Energy meter, record the meter constant, voltage & current rating, initial reading.

3 Check the terminals, resistance of current coil & potential coil of energy meter with multi meter.

TASK 2: Connect the Energy meter and measure the Electrical energy

1 Make the connection of energy meter and load as per circuit diagram.
2 Check the connections and connect the circuit to 1 Ph. Supply through DPST switch.
3 Switch ON the main supply, keep the load switch OFF and observe any disc vibrations OR very slow disc
rotation of energy meter on No-load.
Note: When load is OFF if a very small disc rotation is found it is known as creeping error of meter.

4 Note down the initial reading and meter constant (K) of energy meter.

5 Close the load switch and increase the lamp load up to 10 Amp
6 Record the voltmeter and ammeter readings, observe the disc rotation.
7 Start the Stop watch and count 50 No. of disc revolutions of energy meter, and record the time taken for 50
disc revolutions.

8 After completion of 50 disc revolutions switch OFF the load and record the final reading of energy meter.
9 Switch OFF the supply and disconnect the circuit.
10 Calculate the true energy & recorded energy as per formula given in tabular column.
11 Compare the true energy & recorded energy which must be approximately equal.
12 Repeat the experiment with another energy meter and compare the result.

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