Page 103 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 43 : Loading and determine the efficiency of

single phase transformer

Objectives

At the end of this exercise you shall be able to
• check the primary & secondary voltage and KVA of transformer
• connect and apply resistive & inductive load on transformer
• calculate the losses occurred in transformer and find the efficiency of transformer
• calculate the efficiency of transformer at different loads and power factor.

Requirements

Tools/Equipments/Instruments Materials/Components
• Combination plier (165mm, insulated) - 1 No. • PVC copper wire (1.5 sq.mm) - 2 meter.
• Screw Driver (150mm, insulated stem) - 1 No. • Test lamp (100 W, 230V) - 1 No.
• Neon Tester (75mm, 500 V) - 1 No. • Insulation tape (PVC, 19mm) - 1 role.
• Electrician knife (Insulated) - 1 No. • Cotton waste - as reqd.
• Voltmeter (MI, 300 V) - 2 Nos.
• Ammeter (MI, 10 A) - 2 Nos.
• Watt meter (MI, 10A, 400 V) - 2 Nos.
• 1 Ph. Transformer (400V/230V) - 1 No.
• Lamp load (250 V, 5 KW) - 1 No.
• Inductive load (AC motor) (230V, 2 HP) - 1 No.

Procedure

TASK 1 : Identify the rating of transformer
1 Collect the Tools, equipments and materials required for experiment.
2 Draw the connection diagram of loading & efficiency of 1 ph. transformer.

3 Check the primary & secondary voltages and KVA of transformer.
4 Identify HV & LV side and check full load current of transformer.
5 Collect the data of total losses of transformer determined by OC & SC test.

TASK 2 : Connecting and loading of transformer
1 Make the connection of transformer with all meters and lamp load.

2 Check the connections and connect HV winding of transformer to the supply.
3 Switch ON the supply and record the reading of voltmeter, ammeter and watt meter on HV & LV side.
4 Close the load switch on LV side and increase the load step by step until full load current of transformer.
5 Record the reading of voltmeter, ammeter and watt meter at each steps.

6 Connect the inductive load on the transformer and repeat the steps 2 to 5.
7 Switch OFF the supply, disconnect the circuit & transformer.

86