POE Switches
(60)
CCTV Power Supplies
(82)
Video Baluns
(39)
CCTV Connectors
(74)
CCTV Testers
(19)
CCTV Tools
(17)
CCTV Cables
(15)
CCTV Microphones
(33)
Ethernet Switch
(18)
Video Converters
(3)
Video Extenders
(4)
IP Extenders
(3)
Source: UNIFORE
The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) is an organization within IEEE that develops global standards in a broad range of industries. IEEE electrical classification is a select-able standard in IEEE802.3af standard. LAN Switch or Powered devices manufacturers do not need to execute this class, however, it’s very important to provide flexibility and compatibility for devices.
On the basis of electrical output of power sourcing equipment (PSE), this select-able IEEE802.3af standard can defines 3 different types of electrical classification level and 1 is default mode. Besides, it also defines the maximum electrical output for each level.
| IEEE types | PSE max electric output | PD max electric output |
| 0 | 15.4W | 0.44-12.95W |
| 1 | 4W | 0.44-3.84W |
| 2 | 7W | 3.84-6.49W |
| 3 | 15.4W | 6.49-12.95W |
We know, power transmission through cable will cause voltage drop or power loss. In IEEE802.3af standard, PD device must provide no more than 15.4W power, where on the end of cable, only 12.9W is needed in this standard, it’s same case from power supply to physical PD port.
Yes, majority of PoE switch has adopted the multiply protection, including over current and short-circuit protection. For example, each port of rated current is 250mA, if the current reaches over 400mA and time lasts for 75ms, the switch will cut off the current. If the low-resistant short-circuit cases happen, then it can be checked within 1ms and the current will be cut off at once, after each port restore to normal status, each port will re-start work automatically from over current and short-circuit. Each port has independent protection detection, which means the fault of one port will not affect the working of rest of other ports.
