There are two issues that you have to be aware of when you are evaluating RPS solutions for fixed Cisco catalyst switches. Cisco has a product named Cisco Redundant Power System 2300 (RPS 2300) for the non-modular switch series like Catalyst 3560, Catalyst 3750. This is the successor of old Cisco Redundant Power System 675 (RPS 675).
You have only one bullet in your gun when you have an RPS
Switch draw power from the RPS after power fails
You can provide a limited redundancy to your network by installing an RPS for your Catalyst Switches. Switch survives without rebooting when the main power goes off. It draws power from RPS, but it never returns back to main power. An orange LED shows the switch powered by RPS. If you press the standby/active button on the RPS, your switch will reboot and become a normal operation. The only exception is E series switches + RPS 2300 combination. This combination could restore power state without rebooting.
RPS supports only one switch(in some cases two) at one time
Some of the switches will fail with a power circuit fail
You can attach up to 6 switches to an RPS, but if power Circuit 1 fails as shown in the above scenario then RPS only can support one switch and the rest will fail. RPS 2300 can support 2 switches if the power requirements are moderate, but no more.