Page 106 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 44 : To conduct parallel operation of two 1 ph.

transformers

Objectives

At the end of this exercise you shall be able to
• identify the similar terminals and measure the impedance of transformer.
• check the voltage, frequency, impedance and phase sequence of transformers.
• connect two identical transformers in parallel and test.
• apply the load on transformers connected in parallel and observe the load sharing.

Requirements

Tools/Equipments/Instruments
• Combination plier (165mm, insulated) - 1 No. Materials/Components
• Screw driver (150mm, insulated stem) - 1 No. • PVC copper wire (1.5 sq.mm) - 2 meter.
• Neon Tester (75mm, 500 V) - 1 No. • Test lamp (100 W, 230V) - 1 No.
• Electrician knife (Insulated) - 1 No. • DPST switch (16 A, 230 V) - 1 No.
• Voltmeter (MI, 400 V) - 2 Nos. • Cotton waste - as reqd.
• Ammeter (MI, 10 A) - 2 Nos.
• 1 Ph. Transformer
(400V/230V, 1 KVA) - 2 Nos.
• Multi meter (Digital, 3 digit - 1 No.
1/2
• Lamp load - 1 No.

Procedure

TASK 1 : Check the terminals & sequence of both transformers

1 Collect the Tools, equipments and materials required for experiment.
2 Draw the circuit diagram of parallel operation of 1 ph. transformer.
3 Check and identify the voltage, current and KVA rating of transformers.
4 Check & identify the primary & secondary similar terminals of transformer and mark the terminals numbers
with marker.
5 Place both transformers side by side and primary terminals facing towards incoming line bus-bar, and
secondary terminals facing towards load circuit.

6 Ensure and fulfill the following conditions for parallel operation of transformers.
a) The voltage rating of both transformers must be same.
b) The transformation ratios of both transformers must be equal.
c) The polarity of primary & secondary terminals of both transformers must be identical.

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