The differenc that two power module be inserted in A plane or A and B plane when S9300 switch has only 2 power module.
S9306/s9312 have 4 power slot, PWR1 and PWR2 is load balance for each other, PWR3 and PWR4 is load balance for each other, PWR1 and PWR2 is in A area, PWR3 and PWR4 is in B area. A and B is the relation for master and slave.
The master and slave relationship principle of power is as follows: it cannot appoint which power is master which one is backup.
1. The power module that import voltage higher is as master supply power.
2. When the voltage is equal, the power that supply power first is as master supply power.