A three phase synchronous generator is to be connected to the infinite bus. The lamps are connected as shown in the figure for the synchronization. The phase sequence of bus voltage is $R$-$Y$-$B$ and that of incoming generator voltage is ${R}'.{Y}'.{B}'$

.It was found that the lamps are becoming dark in the sequence $L_a$-$L_b$-$L_c$. It means that the phase sequence of incoming generator is

1. Opposite to infinite bus and its frequency is more than infinite bus
2. opposite to infinite bus but its frequency is less than infinite bus
3. same as infinite bus and its frequency is more than infinite bus
4. same as infinite bus and its frequency is less than infinite bus

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