The PoE injector and PoE splitter working together can deliver 72W (DC12V 6A) remain power to satisfy the applications such as Cellular base stations, Access control with door locks, Televisions and interactive displays, Point of Sales (POS) and information kiosks, etc.
This video would explain why IEEE802.3bt PoE injector and splitter can transport so how power and whether it is safe or not.