Page 117 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 49 : To measure high current & voltage using

CT and PT

Objectives

At the end of this exercise you shall be able to
• check and identify the different types of CT’s & PT’s, and their ratio’s & ratings.
• test the polarity of CT & PT and marking the terminals.
• measure the high voltage & current with CT & PT.
Requirements

Tools/Equipments/Instruments
• Combination plier (165mm, insulated) - 1 No. • CT (Demo type) (30/1 A) - 1 No.
• Screw Driver (150mm) - 1 No. • PT (Demo type) (440/110 V) - 1 No.
• Neon Tester (75mm, 500 V) - 1 No. • Current injection kitj (0-50A) - 1 No.
• Electrician knife (Insulated) - 1 No. • Voltage injection kit (0-600 V) - 1 No.
• Voltmeter (MI, 600 V) - 1 No. Materials/Components
• Voltmeter (MI, 150 V) - 1 No. • PVC copper connecting
• Ammeter (MI, 30 A) - 1 No. probes (2.5 sq.mm) - 5 Nos.
• Ammeter (MI, 5 A) - 1 No. • Test lamp (100 W, 230V) - 1 No.
• Multi meter (Digital, 3 digit) - 1 No.
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Procedure

TASK 1 : Identify the terminal of CT & PT
1 Collect the Tools, equipments and materials required for experiment.
2 Draw the connection diagram of CT and PT.
3 Check the type, construction, voltage & current ratio of CT and PT.
4 Check & identify the polarity of terminals of CT and PT, and mark the terminals as

Primary- P1 & P2
Secondary- S1 & S2
5 Check the connection and rating of current injection kit & voltage injection kit.
Note: 1 For practical experiment purpose use only demo CT & PT’s
2 Never test the High tension CT & PT’s which are tested only under expert supervision.

TASK 2 : Connect and test the CT
1 Make the connection of primary terminals P1 & P2 of CT in series with current injection kit.
2 Make sure that current injection kit is OFF and its knob is at zero position.

3 Connect the secondary terminals S1 & S2 of CT to the ammeter of low range.
4 Switch ON the current injection kit and gradually increase the CT primary current until CT secondary current
reaches 1 Amp.
4 Note down the primary current and secondary current

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