Page 115 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 48 : Test and verify the voltage of 1 Ph & 3 ph.

auto transformer:

Objectives

At the end of this exercise you shall be able to
• check & identify the construction, parts and rating of auto transformer.
• connect and measure the variable output voltage of 1 Ph. Auto transformer.
• connect and measure the variable output voltage of 3 Ph. Auto transformer.
• test the electrical appliances with auto transformer.

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. • Cotton waste - as reqd.
• Electrician knife (Insulated) - 1 No.
• Voltmeter (MI, 600 V) - 2 Nos.
• Multi meter (Digital, 31/2 digit) - 1 No.
• 1 Ph. Auto transformer (0 to 270 V) - 1 No.
• 3 Ph. Auto Transformer (0 to 460 V) - 1 No.

Procedure

TASK 1 : Identify the terminals of 1Ph & 3Ph auto transformer
1 Draw the diagram of 1 Ph. Auto transformer & 3 Ph. Auto transformer.
2 Check the construction, rating and identify the parts of 1 Ph & 3 Ph. Auto transformers.
3 Check the primary and secondary portion of winding of Auto transformers.
4 Check the input & output terminals of 3 Ph. Auto transformer and mark as,
R S T – Input (primary) terminals.

U V W – Output (secondary) terminals.

TASK 2 : Connect and verify the voltage of 1 Ph. Auto transformer
1 Connect the 1 Ph. Auto transformer to the supply and set its knob to zero position.
2 Switch ON the supply and measure the primary input voltage & record.
3 Slowly rotate the knob clockwise and measure the output voltage on secondary terminals.
4 Increase the voltage step by step and record the output voltage until last taping of winding.

5 Reduce the voltage to zero and switch OFF the supply & disconnect the auto transformer.

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