Page 191 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 79 : Synchronise (by Parallel Operation)
Alternators by Different Methods

Objectives

At the end of this exercise you shall be able to:
• draw the circuit diagram to synchronize an alternator by dark lamp method
• connect the circuit to synchronize the alternator to the busbar by bright lamp method
• synchronize the alternators by synchroscope method.

Requirements

Tools/Instruments
• Combination pliers 150mm -1 No. • ICTP 16A, 440V -2 Nos.
• Screw driver 100mm -1 No. • Phase sequence meter 3HP, 415V -1 No.
• Electrician’s knife 75mm -1 No. • Variable DC source 0 – 250V -1 No.
• Frequency meter 47-53Hz -1 No. • Synchroscope 1500 W,230 V -1 No.
• Voltmeter MI 0 – 500V -1 No. Materials
Equipments/Machines
• PVC insulated Copper wire 1.5mm -9 m.
2
• 3Ф Alternator 2kVA, 2.9A, 50Hz -2 Nos. • 4 core cable 650-1100V -6 m
• 3Ф Auto-transformer 0-415V, 16A -1 No. • Lamp 40W -6 Nos.
• DOL starter 3HP, 440V -2 Nos.

Procedure

TASK 1: Dark lamp method
1 Make the connections as per the circuit diagram for bright lamp method. Fig 1

2 Switch on the supply and run the prime mover and alternator.
3 Switch ON and vary the DC excitation supply to build rated voltage of alternator.
4 Check the phase sequence of the bus bar and incoming machine using phase sequence indicator.
5 Connect the phases of incoming machine in ICTP so as to match the phase sequence of busbar.

6 Adjust the voltage of incoming alternator to match that of busbar by varying excitation.
7 Adjust the frequency of incoming alternator to match that of busbar by varying speed of prime mover.
8 Vary the prime mover to get the dark condition of the lamps connected directly between two phases
9 Close the synchronizing switch when the condition at above step is met.

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