To understand how to distinguish whether a Poe switch is powered by a standard Poe, you must first figure out what a Poe switch is.
Poe power supply switch refers to the switch that can provide network power for remote power receiving terminal through network cable. It includes two functions: network switch and Poe power supply. It is a common power supply equipment in Poe power supply system.
Classification of Poe switches
1. Standard Poe switch
Conforming to IEEE802.3af and 802.3at standards, it is a standard Poe switch (commonly known as 48V). The complete Poe includes two parts: PSE (power sourcing equipment) and Pd (power device). Poe switch is one of PSE devices. PSE is the equipment that supplies power to the terminal and the manager of Poe Ethernet power supply process. PD is the terminal equipment receiving power supply (48V national standard equipment contains PD chip).
2. There are two types of non-standard Poe switches.
Instead, it is a non-standard Poe switch ("non-standard" is abbreviated to "non-standard" commonly known as 24V, but not marked with 48V, 24V, 12V, 5V, etc.).
Main application fields of Poe switch
Poe switch mainly provides network and power supply for monitoring (power supply for camera), wireless coverage (power supply for AP), wireless transmission (power supply for network bridge) and other equipment.
Working process of standard Poe power supply switch
1. Detection: the POE switch first outputs a very small voltage, and detects the power receiving end equipment containing ieee802.3at/af standard chips (ieee802.3at/af standard chips are referred to as "PD").
2. PD classification: after PD is detected, Poe switch classifies PD equipment and evaluates the power of PD equipment.
3. Power supply: during the startup period (generally less than 15 μ s) The POE switch supplies power to PD from low voltage until the voltage required by PD is sufficient to provide stable and reliable DC power for PD equipment.
4. Power off: if the PD equipment is disconnected, the POE exchange will quickly (generally within 300 ~ 400ms) stop supplying power to the PD, and repeat the detection process to detect whether the terminal of the cable is connected to the PD equipment.
Universal meter test method for true and false Poe
Start the equipment, adjust the multimeter to the voltage measurement gear, and touch the power supply pin of PSE equipment (usually 1/2,3/6 or 4/5,7/8 of RJ45 port) with two probes of the multimeter. If 48V or other voltage values (12V, 24V, etc.) are measured, the equipment with stable output is a non-standard product. Because in this process, PSE does not detect the power receiving equipment (here is the multimeter), and directly uses 48V or other voltage values for power supply.
On the contrary, if the voltage cannot be measured and the multimeter needle jumps between 2 and 10V, it is a standard Poe. Because at this stage, PSE is detecting the PD terminal (here, the multimeter), and the multimeter is not a legal PD, PSE will not supply power and no stable voltage will be generated.
After mastering the above judgment methods, we can distinguish whether a Poe switch is powered by a standard Poe.
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