PD: A switch that is itself supplied with PoE

Switches that have PoE outputs are nothing new - but it becomes interesting when switches themselves are supplied with PoE, i.e. they have a PoE input. Why is this important? Imagine you are using a manageable PoE switch with many ports in a storey cabling system, which now connects the switches to the to the workstations. If you now use a PoE Powered Switch at the workstations, you can save all power supplies. In addition, you can switch the ports of the PD switches on or off using the manageable switch, for example time-controlled. Of course, this also offers a security aspect: no power supply - no access to data on IP phones, computers, etc. Or let's look at another case: You want to install an access point or IP camera at a location in the building where there simply is no power outlet nearby. Here, a PD switch is used which can be controlled by a manageable switch, as in the previous example. Even more extreme is the case in a large warehouse: let's say the nearest power connection is 700 meters away, but you still have to install an IP camera in the back corner. No problem with the LT PoE Switch (with 90W!)
and a LT PoE repeater that can refresh the PoE signal every 100 meters - 6 times in a row!