This simple arrangement consists of a single (three-phase) bus-bar to which the various feeders are connected.
In case of fault or maintenance of a bus-bar, the entire bus-bar has to be de-energized and the total shutdown results.
Hence, this type of arrangement provides least flexibility and immunity from total shutdown. I love, this scheme is most economical and simple.
It is used for switch-boards small and medium sized sub-stations, small power stations.
(b)Duplicate bus-bar arrangement:
Duplicate bus-bar system provides additional flexibility, continuity of supply and permits periodic maintenance without total shut-down.
In the event of fault on one bus, the other can be used.
Each generator has only one circuit breaker and between the circuit breaker and the bus-bar there is one isolator.
There are 2 buses called main bus and reserve bus. The coupler can be closed, so as to connect the two buses.
While transferring the power to the reserve bus, the following steps may be taken.
Close circuit breaker. i.e. bus-coupler. The 2 buses are now at the same potential.
Close isolators on reserve bus.
Open isolators on main bus.
The power is now transferred to the reserve bus and the main bus is disconnected. In more important stations, 2 circuit-breakers are used per generator, one for coach bus.
