One Dark and Two Bright Lamp Method of Synchronism with Suitable Sketches and Phasor Diagram
Q. Explain one dark and two bright lamp method of synchronism with suitable Sketches and phasor diagram.
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| One dark, two equally bright method of synchrosing |
In this method, the lamp connections are made as shown in Figure (B). One lamp is directly connected across R – R’and the other two are cross-connected. The proper instant of synchronising will be when the alternator voltage phasors and bus-bar voltage phasors are in phase as shown in Fig.C. At this instant, lamp connected across R-R’ will receive zero voltages and will be dark. The lamps across Y-B1, and across BY ‘ will receive large and equal voltages and will glow equally bright. This is the proper instant of synchronising. But when alternator voltages phasors are not in phase with the bus bar voltage phasors as shown in Fig.D the three lamps will glow with unequal brightness. The speed the primemover is adjusted for obtaining the correct instant.
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| Lamp connections |
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| (Phaser Diagram) proper instant of synchronising |
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(Phaser Diagram) Improper instant of synchronising
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