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Which power supply is 1236 and 4578 in the POE switch?
A friend asked if he could use a telephone line to connect to POE or use a four-core network cable to make the crystal head. Many friends are confused about which power supply is 1236 and 4578 in the network cable? We have mentioned similar issues in this question before, and today we will take a full look at it again.
1. Which one transmits data and which power supply?
There are two standard Poe switches, 802.11af and 802.11at. Both of these standard Poe switches support two power supply modes:
â‘ 1236 both data and power supply;
â‘¡1236 go data, 4578 power supply;
Second, which power supply method is actually used
Which power supply method is actually used depends on the POE switch. These two power supply methods are compatible with our cameras that support POE. Poe will determine which power supply method to use according to the situation.
Due to the 1, 2, 3, and 6 cores used in 100M communication, all 8 cores are used in Gigabit communication. therefore:
1. For 100M PoE switches: Under the power supply standard, the network cable only needs to be connected with 1, 2, 3, and 6 cores, which can take data and power; of course, if you want to take 1236 data and 4578 power, then you need an 8-core network cable, and Ensure that all 8 cores are connected.
2. For Gigabit PoE switches: Limited by the need for data transmission, no matter which way is provided, all 8-core network cables are required to be connected.
3. What are the two standards of POE switches
IEEE802.3af power supply 15.4W, if the camera power is 10W, you can use 802.af power supply switch;
IEEE802.3at power supply is 30W, if the camera power is 20W, you need to use 802.3at POE switch;
802.3at is backward compatible with 802.3af, so cameras that support 802.3af can be powered by 802.3af or at switches;
Cameras that support 802.3at can only use 802.3at switch power supply;
For some high-power front-end devices, such as dome cameras, the output power cannot meet the requirements and cannot be powered by POE switches.
For example, some dome cameras have a power of 40W, and the single-port PoE power does not exceed 30W, and the single-port power of the switch cannot be met. Therefore, the dome camera's own POE module is required for power supply. I got it right when I bought it.
4. How far is the POE power supply?
Regarding the power supply distance of the poe, there have been many friends in the weak current VIP technology group discussing whether the power supply of the poe can exceed 100 meters? This problem is indeed affected by many factors. Some friends have no impact on the power supply beyond 100 meters, and some have experienced instability at 90 meters. We will discuss it together.
You must see the 200-meter, 250-meter, and 300-meter PoE power switch products advertised in the circle of friends or online. There will be a doubt: is the transmission distance of the network cable not 100 meters? What kind of thread can we use to reach the distance of publicity?
Long-distance transmission over 100 meters or more must exceed category 5 and be an 8-core network cable. At the same time, the poe switch is powered by 8 cores, and the camera must also be powered by 8 cores. The key point is that the PoE switch device supports the network extension mode. When it is turned on, the data transmission and power supply distance of the corresponding port can reach more than 100 meters when using Super Cat.5 and Internet access lines. For ordinary poe switches, we recommend 100 meters Less suitable.
Why is it recommended to use it within a distance of 100 meters?
Let's take a look at the resistance of various network cables.
100m resistance of various types of network cables of super five types of twisted pairs:
1. Copper clad steel network cable: 75-100
2. Copper clad aluminum network cable: 24-28
3. Copper-clad silver network cable: 15
4. Copper-clad copper network cable: 42
5. Oxygen-free copper network cable: 9.5
The shorter the distance, the smaller the resistance. Among them, the oxygen-free copper cable has a small resistance, so the power supply is stable with it. The resistance at 100 meters is only 9.5. What if it is 50 meters? Then its resistance is half of 9.5, the smaller the power loss of the poe power supply (the power loss formula, Q = I²Rt, the power loss is proportional to the resistance), then the more stable the power supply. Therefore, use a good network cable for transmission over a distance of more than 100 meters.