Bahçeşehir University

Faculty of Engineering

Electrical and Electronics Engineering Department

Electromechanical Energy Conversion Laboratory

Prepared by F.Kemal BAYAT Page 1 of 4

Experiment 5 Synchronous Generator

PRELIMINARY STUDIES In this section you should read your lecture notes and answer following questions before coming to the laboratory. There will be a quiz concerning these questions. Q1.What is the relationship between frequency and angular velocity? Q2. What is the relationship between frequency and synchronous speed? Q3.How does the pole number of a synchronous machine effect speed and/or frequency? Q4.How many poles does a 1500 rpm synchronous generator have? CONDITIONS FOR PARALLEL OPERATION OF ALTERNATORS

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Bahçeşehir University

Faculty of Engineering

Electrical and Electronics Engineering Department

Electromechanical Energy Conversion Laboratory

Prepared by F.Kemal BAYAT Page 2 of 4

EXPERIMENT

Bahçeşehir University

Faculty of Engineering

Electrical and Electronics Engineering Department

Electromechanical Energy Conversion Laboratory

Prepared by F.Kemal BAYAT Page 3 of 4

Bahçeşehir University

Faculty of Engineering

Electrical and Electronics Engineering Department

Electromechanical Energy Conversion Laboratory

Prepared by F.Kemal BAYAT Page 4 of 4

C.Parallel Operation Part.1. Circuit is connected as the lamp-type synchroscope connected across the synchronizing switch S - (straight - connected type). While the switch S is open, start the DC driving motor (prime mover) and adjust its speed to a value close to the synchronous speed of the machine. Next, adjust the line-to-line voltage of the synchronous generator to its rated value. Slowly, increase the field current of the synchronous machine until the line-to-line voltage across the machine terminals of the synchronizing switch is equal to that across the supply terminals. Check the phase sequence of the voltages on the machine and the supply terminals of the synchronizing switch using a phase-sequence meter and synchroscope. If the phase sequence of the machine and supply are different, switch off the three-phase supply and interchange any two lines. It will be observed that the lamps of the synchroscope now flash on and off in unison. Close the synchronizing switch, S, when the lamps are out. Then open switch S and observe that the machine continues to run at synchronous speed. Part.2. Repeat Part.1 above with the synchroscope "cross-connected", In this case, the lamps will light up sequentially (one by one). Observe the changes in the sequence of the bright lamps as the speed of the machine is varied below, through and above the synchronous speed of the synchronous machine. Close the synchronizing switch, S when the directly-connected lamp is out. Q5.What happens if we do not equal voltages of the two generators that we connect in parallel? Q6.What happens if we do not equal frequencies of the two generators that we connect in parallel? Q7.What happens if we do not adjust the phase sequences of the two generators that we connect in parallel? Q8.Consider a three-phase synchronous generator providing 60 Hz voltages. Find the synchronous speed in rpm for machines with two, four, and six poles. Show all your calculation.