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01) What is PoE?

PoE is " Power over Etherenet". A device like this one take DC power and injects on one or both pairs of wire in the Ethernet cable. It's used to power IP cameras, VOIP phones, Wifi Access Points and other networks devices.

02) What are standard PoE and non-standard PoE? How should I choose between them?

Standard Power over Ethernet (PoE) and non-standard PoE are two different power supply methods with some differences in communication protocols and power transmission between devices.

Standard PoE adheres to IEEE standards, primarily including IEEE 802.3af and IEEE 802.3at (also known as PoE+), as well as the updated and extended IEEE 802.3bt (PoE++) standard. These standards specify the communication protocols between Power Sourcing Equipment (PSE) and Powered Devices (PD), as well as the specifications for power transmission.

In standard PoE, both PSE and PD products have built-in PoE chips (except for MCU solutions) that perform a handshake and level allocation before power delivery begins, ensuring that devices can safely receive the required power. This intelligent power supply method enhances system security and reliability.

Non-standard PoE, also known as passive PoE, is a simpler power supply method that does not involve intelligent handshakes and level allocations; power transmission is mandatory. Due to the lack of intelligent pairing in passive PoE, it is cost-effective but comes with some risks, especially when devices' RJ-45 ports do not support PoE or when the voltage is below 48V, potentially leading to device damage.

The voltage for standard PoE typically ranges from 37V to 57V, depending on the standard type. The voltage range for non-standard PoE can be 5-57V (not recommended for transmitting PoE below 24V), making it flexible in application.

The choice between standard PoE and non-standard PoE often depends on the specific requirements of the application. Standard PoE offers higher intelligence and security, suitable for scenarios with demanding requirements in these aspects. Non-standard PoE is more flexible and cost-effective, providing an alternative for simpler application scenarios and customer groups sensitive to costs.

03) What is the choice between PoE switch and PoE midspan? With a PoE switch, do I still need a PoE midspan?

The widespread adoption of Power over Ethernet (PoE) technology eliminates the reliance of network devices on nearby power outlets, instead providing power through data cable. In the PoE ecosystem, PoE switches and PoE injectors are key components for powering network devices. The simplest distinction between them lies in the fact that PoE switches operate in a one-to-many mode, while PoE injectors provide power in a one-to-one fashion and need to be used in conjunction with regular network switches or PoE switches.

If you already have a non-PoE switch, you can opt to add PoE injectors to the network, enabling existing devices to benefit from PoE without the need to replace the entire switch. 

Additionally, when the power supplied by PoE switches is insufficient for supporting high-power devices, adding PoE injectors can provide additional power support to ensure all devices operate smoothly.

Beyond supplementing power and upgrading existing network capabilities, PoE injectors offer a more flexible approach. Users can selectively choose where to add PoE functionality in the network based on specific needs. This selective power supply method allows for better meeting the requirements of particular devices without the need for extensive changes to the entire network.

04) What are the differences between 48V or 56V passive PoE and standard 802.3af/at PoE? Can they be used together?

Standard 802.3af/at PoE typically involves an intelligent pairing through a handshake protocol, ensuring proper communication before power delivery begins, thereby safely providing or accepting power. In contrast, passive PoE utilizes mandatory power supply without the protocol of intelligent pairing.

In most cases, 48V passive PoE can supply power to standard 802.3af and 802.3at devices because 48V is one of the operating voltages for both standard PoE types. The 802.3af/at standards specify that the voltage supplied by Power Sourcing Equipment (PSE) should be between 37-57V, with the standard-prescribed voltage being 48V. Therefore, 48V passive PoE can typically meet the requirements of 802.3af/at standards.

Since PDs (Powered Devices) compliant with 802.3af and most 802.3at devices usually only detect voltage, any PD device compliant with the 802.3af standard and most 802.3at devices will automatically activate and start accepting power when the PoE voltage supplied by the PSE is within the 37-57V range. Both 48V and 56V passive PoE can work seamlessly with standard 802.3af and 802.3at PoE.

However, it's important to note that standard PoE incorporates some protective measures for RJ-45 ports that do not support PoE, ensuring that devices are not damaged during voltage transmission. Passive PoE may lack these protective mechanisms, posing some potential risks and the possibility of device damage. Therefore, when selecting PoE devices, it's crucial to consult the device specifications to confirm compatibility.

05) What's difference in Mode A and Mode B?

When discussing Power over Ethernet (PoE) supply methods, we typically refer to Mode A and Mode B. 

In Mode A, PSE devices choose to supply power on pins 1/2 and 3/6, which can be either 1/2+ 3/6- or 1/2- 3/6+. For PD devices that support Mode A power supply, they need to be capable of simultaneously supporting both 1/2+ 3/6- and 1/2- 3/6+ scenarios.

On the other hand, some PSE devices use Mode B, transmitting power through 4/5+ 7/8-. This is commonly found in certain products from brands like Mikrotik and UBNT. It's worth noting that there is an alternative in Mode B where PD devices are powered through 4/5- 7/8+, but this configuration is exceptionally rare and is found in some older models from Cisco and Cambium.

Furthermore, many PSE and PD devices support the simultaneous use of both Mode A and Mode B for power supply and reception, especially as mandated by the 802.3bt standard, which requires the use of all four pairs of wires for power delivery and receipt.

06) How to select the PoE Injector?

First, check the power consumption specifications of the powered devices to verify whether they support PoE and which PoE standards they adhere to. 
Next, determine how many devices need simultaneous power supply and calculate the total power requirement. 
Finally, select the appropriate PoE power supply equipment and power source.

For example, if the existing switch does not support PoE functionality, and you have 8 cameras that are PoE-enabled, supporting 802.3af PoE/12V DC with a maximum power consumption of 6W each, in such a scenario, you can opt for the GPOE-8A-48V60W kit (8-port Gigabit A-mode PoE injector and 48V60W power supply) to provide power and transmit data for all 8 PoE cameras.

Please take noted that if the devices support 802.3af PoE/12V DC, it indicates that when utilizing PoE functionality, a 48V power source is needed. When using a 12V power source, the device is directly powered with 12V DC.

07) Can 24V and 48V works in one POE Injecor?

Yes, you just need an PoE converter, from 48V to 24V or from 24V to 28V PoE.

Our GAF-24V24W,GAT-24V-25W, GPOE-48V10W can meet this kind of requirement. 

08) Which power supply do I need?

Our PoE power supply devices, including injectors and switches, utilize external power sources. Connecting different devices only requires swapping out the power source, providing users with greater flexibility.

Passive PoE injectors support voltage inputs ranging from 12-56V. Depending on the PoE standard of the powered device, users can choose a 24V or 48V power source. Active PoE injectors support voltages between 44-56V, allowing the use of either a 48V or 56V power source.

It's important to note that if a device supports 802.3af PoE/12V DC, it indicates the need for a 48V power source when utilizing PoE functionality. When using a 12V power source, the device is directly powered with 12V DC.

For instance, if each powered device requires 6W, and you are simultaneously connecting 10 devices, you would need a total power consumption of 60W. If the devices support 24V PoE, then choosing a 24V60W power source is suitable. If they support 802.3af PoE, then a 48V60W power source would be appropriate.

If you opt for our bundled combinations, they come with the corresponding power supply.

09) How to address insufficient power in PoE ports?

According to IEEE standards, each PSE port for 802.3af should output 15W, each port for 802.3at (PoE+) should provide 30W, and for 802.3bt (PoE++), ports are categorized into Type 3 and Type 4 with power levels of 60W and 90W, respectively. However, in practical applications, many PoE-powered devices (PDs), especially security cameras and network access points (APs), typically require only 2-6W of power, well below the standards. This often results in PoE switches supporting much lower power than the specified standards.

To address this issue, PoE switches can be treated as regular switches and connected to a PoE injector. This ensures that each PoE injector port has sufficient power output. For example, for an 8-port injector, if connected to 802.3af devices, a minimum of 120W power supply is required; for 802.3at devices, a minimum of 240W power supply is needed, and for devices using 802.3bt Type 3, a minimum of 480W power supply is necessary.

Implementing a PoE injector solution allows for more flexibility in meeting the power requirements of different devices, avoiding energy waste and optimizing device resources. When deploying a PoE network, it's crucial to carefully plan and assess the power requirements of devices to ensure that the power supply system can effectively meet the needs of each device.