In a newbie, but my understanding is that the power supply is under powered. This means that while you have 24 or 48 ports that can support POE, if every port is needing to send out full POE power (like 30 watts for example), the switch won't be able to do it and will cut power to some ports in order to power the rest. You can specify a hierarchy of devices so critical devices are powered off last.
However, many POE devices are not that power hungry. For example, I have a fix of POE CCTV cameras, wireless APs, and IP phones hooked up to my switch and none of them draw more than about 5v. Many draw considerably less than that (2.5v or even less than 1 v). No perhaps those devices were in a low power state when I checked the power consumption levels and they will draw more power under certain circumstances. But long story short, even with my plans to add a few more POE devices, I should have plenty of power available with this switch.