Redundant power supply operates in (N+1) redundant system with two power supply modules connected in parallel where when one module fails, the other can take over.
When 100W output is required, for example, two 50W power supplies in parallel connection can afford the power. By adding another 50W power supply (+1), when one module fails, the other two keeps running to operate without problem. This is redundant system (Figure 2.6).

Fig. 2.6　N+1 redundant operation

That is, by (N+1) redundant operation, reliability of system can be enhanced.

Also, with "hot-swappable," availability can be increased.