Page 95 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 39 : To measure and improve the Power factor

of AC circuit

Objectives

At the end of this exercise you shall be able to:
• identify the power factor meter, check its terminals, scale, rating and connection
• connect the inductive & resistive loads in AC circuit and measure the power factor
• connect the required value of capacitors to improve the power factor in AC circuits.

Requirements

Tools/Equipments/Instruments
• Combination Plier 165mm, insulated • Resistive (lamp) load
-1 No. 1 Ph. 230V, 5KW -1 No.
• Screw Driver 150mm, -1 No. • Inductive load (Ind. Motors,
• Neon Tester 75mm, 500 V -1 No. choke) 1 Phase, 230 V -1 No.
• Electrician knife insulated -1 No. Materials/Components
• Voltmeter MC, 300 V -1 No. • PVC copper wire 1.5 sq.mm -2 meter.
• Ammeter MI, 10 A -1 No. • Static capacitors 2.5 µf
• 1 Ph. Power factor meter, A n a l o g 400 V,5 µf 400 V -Each 4 Nos.
10 A, 230 V -1 No. • Test lamp 100 W, 230V -1 No.
• Multi meter Digital, 3 digit -1 No. • DPST switch 16 A, 230 V -1 No.
1/2

Procedure

TASK 1 : Identify the resistive & inductive loads & PF meters
1 Draw the neat circuit diagram of measurement of power factor in 1 Ph. AC resistive load, Inductive load and
capacitive load.
2 Check & study the Power factor meter- check the terminals, scale, rating & connection.
3 Collect the different static capacitors and check their values
4 Calculate the VAR / KVAR value of capacitors required to improve the power factor of AC circuit.

TASK 2 : Connect and measure the power factor in AC resistive & inductive circuits
1 Make the circuit connection of resistive load as per circuit diagram.
2 Check the circuit and connect to 1 Ph. AC supply through DPST switch.

3 Switch ON the supply, check the power factor meter reading and record in tabular column
4 Switch OFF the supply and make the circuit connection of inductive load as per circuit diagram.
5 Switch ON the supply, check the power factor meter reading and record in tabular column.
6 Switch OFF the supply, and connect one static capacitor in parallel with inductive load.
7 Switch ON the supply and check the change in power factor meter reading & record the same.

8 Connect multiple No. of capacitors until the power factor improves to 1 (unity).
9 Check the ammeter reading for decrease in current when power factor value comes to 1 (unity).
10 Switch OFF the supply and disconnect the circuit.

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