Page 97 - CITS - Electrician - Trade Practical
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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.
                                1/2
            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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