Table of Contents

DIY PoE switch

If you are friends with a soldering iron to power 2-3 PoE devices, you can use an ordinary inexpensive old switch that has been gathering dust in a desk drawer for a long time.

connect, injector, video, camera

I used the Acorp HU5D switch, which had been lying around for a long time. In his circuit there is a converter that lowers the voltage from 15 to 3.3 volts. That is, with a minor alteration, you can use 4 ports for PoE.
It is necessary to remove several resistors soldered between pins 4,5,7,8 from the Acorp switch circuit (marked in red in the photo).

After that, you can supply power to ports 2 through 5 by means of a wall-mounted installation, the first one is used as an uplink. On 8/7 (brown / white-brown) minus terminal and 4/5 (blue / white-blue) plus terminals.

PoE (Power-over-Ethernet) technology was created for IP telephony, access points, IP cameras and other devices to which it is undesirable to run a separate power cable. PoE technology does not affect the quality of data transmission, the potential of the Ethernet level is used, that is, network cables.

It is important to understand that a power supply device (such as a PoE router) will only supply power to the cable if the connected device (such as an IP camera) supports PoE. How does this happen?

1) First, a check is made: whether the connected device is powered (PD). A voltage from 2.8 to 10 V is applied to it, the input resistance of the connected device is determined. If the parameters correspond to the required ones, the power supply goes to the next step.

2) The power supply determines the power consumption of the connected device, for subsequent control of this power. Depending on the power, the devices are assigned a class: from 0 to 4.

Class W per PoE port W per device
15.4 from 0.44 to 12.95
one 4.5 from 0.44 to 3.84
2 7 3.84 to 6.49
3 15.4 6.49 to 12.95
four thirty from 12.95 to 25.5

After the device is classified, a voltage of 48V is applied to it with a rise time of no more than 400 ms, and the power supply begins to control its operation:

1) If the device consumes less than 5 mA for 400ms, then the power supply stops;
2) If the resistance of the connected device is greater than 1980 kΩ for 400 ms, the power supply is interrupted.
3) If the current consumption exceeds 400 mA for 75 ms, the power supply is interrupted.

PoE. IEEE 802.3af

Injector and splitter

There are several ways to apply voltage to the cable. If you stopped at 12 volts, just take them from the computer power supply (it is very convenient to power the router from a computer connected to it). If you use 48 volts, then you need a special power supply, like some kind of AC-DC converter.

On the side of the receiver, we will install the converter, and we will get any voltage necessary for the device, most likely 9 or 12 volts.

It is imperative to put capacitors (electrolytes for a couple of hundred microfarads of ceramics or, better, a film of 10-100 nF) at both ends of the line so as not to turn it into an antenna.

Of course, there is no control over the state of the line, over the needs of the receivers. all that is in the PoE standard. However, not all manufacturers of such devices themselves fully follow the standard. Many implement Passive PoE, which is completely identical to the homemade product we reviewed

What voltage is supplied through PoE?

Power supply of almost all PoE devices (VoIP phones, switches, video cameras, Wi-Fi access points, etc.) is usually 5 or 12 volts, but 48 volts DC is transmitted over the twisted pair to power them, which allows to reduce voltage drops for large distance.
Each device that receives power via PoE has a converter that steps down the voltage to the required.
As a rule, the PoE switch itself determines which equipment is connected and, if necessary, supplies power, i.e. if you connect the network card of a computer or laptop to the PoE switch, it will not burn out and will work normally.

Recently, bimetal twisted pair has become widespread, as a rule it is an aluminum wire covered with a copper layer. Such a wire is much cheaper than a solid copper wire, but the voltage drop across it is much higher, in practical terms, this means that after 50-60 meters the link may be lost.

Second option, backup.

The second option is to remember that all differential pairs in Ethernet are galvanically isolated, and consider the standard circuit of the input stages of any network card:

We see that TX and TX- enter the communication transformer, which has a tap from the midpoint. RX and RX- are similar. This means that we can raise any pair to any (of course, not too high) voltage. To do this, you just need to connect the plus and minus of the power source to the midpoints of the transformers (on the diagram, these are pins 8 and 11). In some network girls and routers, there are additionally 75 ohm equalizing resistors. they will need to be evaporated or the tracks going to them must be cut.

Now you can combine the two methods, and run each voltage line in two pairs. For example, “plus” for orange and brown, and “minus” for blue and green. This method is useful if you need to transfer a relatively large current.

There are 3 PoE standards in total, how they differ?

PoE standards

  • Passive PoE is the most common form of power, which is transmitted over unused wires for data transmission. Brown / white-brown minus, blue / white-blue plus.
  • Active PoE. Power is supplied along with data orange / white-orange plus, green / white-green minus. The rest of the wires are not used.
  • Active PoE — All wires are used for power, allowing for increased load.

What you need to know about PoE before reworking a switch

How to make a simple DIY PoE splitter

The simplest power injector in the 802.3af standard (PoE-B or Passive PoE option) is usually made from an RJ-45 wall outlet and a 12-24 volt power supply (whichever is at hand).

For ease of connection, you can use a 12V power connector with a terminal block. this costs 30 rubles.
If you plan to forward PoE over a considerable distance, you will have to look for a 48 volt power source.

With a patch panel and a powerful 48-volt power supply at hand, you can make a 16-port PoE splitter.

What you need to know about PoE before reworking a switch

There are different tasks in IT and solutions often have to be looked for non-standard. A simple example, you need to install an IP video camera with PoE power supply at a distance of almost 300 meters from the object. PoE specification says that you can up to 100m and what to do here?
There are few options, pull copper with two switches after 100 meters (as intermediate nodes) or forward through optics (of course, if there is an optical port on the equipment) and then install a switch with PoE to power the video camera.

PoE standards

  • Passive PoE is the most common form of power, which is transmitted over unused wires for data transmission. Brown / white-brown minus, blue / white-blue plus.
  • Active PoE. Power is supplied along with data orange / white-orange plus, green / white-green minus. The rest of the wires are not used.
  • Active PoE — All wires are used for power, allowing for increased load.

What voltage is supplied through PoE?

Power supply of almost all PoE devices (VoIP phones, switches, video cameras, Wi-Fi access points, etc.) is usually 5 or 12 volts, but 48 volts DC is transmitted over the twisted pair to power them, which allows to reduce voltage drops for large distance.
Each device that receives power via PoE has a converter that steps down the voltage to the required.
As a rule, the PoE switch itself determines which equipment is connected and, if necessary, supplies power, i.e. if you connect the network card of a computer or laptop to the PoE switch, it will not burn out and will work normally.

Recently, bimetal twisted pair has become widespread, as a rule it is an aluminum wire covered with a copper layer. Such a wire is much cheaper than a solid copper wire, but the voltage drop across it is much higher, in practical terms, this means that after 50-60 meters the link may be lost.

Do-it-yourself PoE switch for a camcorder

DIY PoE switch

If you are friends with a soldering iron to power 2-3 PoE devices, you can use an ordinary inexpensive old switch that has been gathering dust in a drawer for a long time.

I used the Acorp HU5D switch, which had been lying around for a long time. In his circuit there is a converter that lowers the voltage from 15 to 3.3 volts. That is, with a minor rework, you can use 4 ports for PoE.
It is necessary to remove several resistors soldered between pins 4,5,7,8 from the Acorp switch circuit (marked in red in the photo).

After that, you can supply power to ports 2 through 5 by means of a wall-mounted installation, the first one is used as an uplink. On 8/7 (brown / white-brown) minus terminal and 4/5 (blue / white-blue) plus terminals.

READ  WI-FI smart camera how to connect to PC

Add. devices that do not support PoE

PoE is often provided for powering IP cameras as it reduces the number of cables required for each camera. However, some applications require separate power supplies:

Using a heater / fan for outdoor cameras is the most common situation requiring a separate power supply in IP video surveillance systems. Fixed outdoor cameras often consume 20-30W, and PTZ cameras often use 60 to 90W. Such power consumption will not support standard PoE, and many other power supplies.

In older installations, analog cameras are often powered by a transformer connected to the camera, so replacing them with IP should use these resources and thereby reduce costs.

When using Ethernet over coaxial or fiber, the camera requires a separate power supply as neither of these cable types provide the required power.

When using IR illumination, as a rule, separate power supply is required. Raytec has developed fixtures that accept PoE power, but they can only be used if a PoE adapter is used. If the PoE switch has additional power, or an adapter is used, the PoE backlight may work well, but according to the HiPoE standard. Note that many high-power IR illuminators will require 120-240 VAC, not low voltage.

When using wireless transmission systems, local amplifiers are required. Some wireless transmission systems offer PoE outputs to reduce the number of connections.

What you need to know to calculate the power requirement for CCTV cameras?

A quick guide to get you started:
Power W (W). Watts;
Voltage V (V). Volts;
Amperage A. Amperes
Resistance Ohms. Ohms

Power supply for surveillance cameras is an important element of a video surveillance system, which, unfortunately, is not given enough attention. But mistakes in design can lead to significant “gaps” in the reliability of the system.

To understand how much electricity a camera requires, you need to know the following:

Voltage current, for example, 24V @ 4A. You probably saw such a combination in the specifications. This is the value of the output voltage and total current.
Power, for example 9W: it is usually indicated in the specifications of the camera, according to the appropriate voltage.
To convert power to watts and vice versa, the following formulas should be used:

Power (watts) = current (amperes) x voltage (volts)
Current (in Amperes) = power (in watts) ÷ voltage (in volts)
Using this, let’s calculate an example:

For example, we can see that this camera draws 0.75 amperes, or 750 milliamps, at 12 VDC (= 9/12 = ¾ =.75) and 0.375 amps, or 375 milliamps. at 24 VAC (A = 9/24 = 3/8 =.375).

It is important to do these calculations in order to correctly calculate the power consumption of the camera.

Power Form Factors for CCTV Cameras.

Most systems consist of cameras with multiple power outputs. These devices are available in a wide variety of configurations. Most often, if the recorder is rack-mounted, the power supply will be in the rack with it to reduce the amount of cables. The number of outputs to these power supplies is a multiple of four for using cameras in combination with video recorders, which usually have 4, 8, 16 or 32 inputs.

Low voltage power supplies are also available in systems with accessories. This form factor is rarely used these days, but may still be needed for upgrades or in the case of a small system. The inclusion of multiple cameras in one location with output to one power supply significantly increases the number of AC outlets, so it is not recommended.

Another consideration, as for blocks with one-. and for units with multi outputs, it is where they will be located indoors or outdoors. Open source power supplies are built with components that can withstand large fluctuations in temperature and humidity, and are typically weather-protected in a NEMA enclosure. These devices can be installed directly on the camera body during installation and no other protection is required. The ability to install these power supplies directly into the elements of the system usually adds 50-100 to the cost of the device.

Power over Ethernet

Most IP video surveillance systems today use PoE. delivering power over a single Ethernet cable. which is for transferring data between a camera or other device and a switch.

There are two options for doing this: adapter and injector. The PoE power injector attaches directly to the switch for easy installation. The adapter introduces an additional component between the switch and the camera. Cables are routed from the switch to the adapter, and from the adapter to the camera. Adapters are often used when retrofitting existing systems.

PoE is defined in two IEEE standards, 802.3af-2003 and 802.3at-2009. The first, 802.3af, supports power up to 12.95W with a minimum of 44VDC. A new standard, 802.3at, also known as PoE or PoE Plus, specifies up to 25.50W to power the device. There are devices on the market that are capable of delivering more power, in some cases up to almost 100W, but they are not supported by the simple 802.3 standard. PoE provides more power than just PoE. It allows you to connect more power-hungry devices with one cable. PTZ cameras and housings are equipped with heaters that cannot be powered by PoE or PoE This requires an additional cable that will be connected to a separate power source, which of course increases the cost of the system.

Selection of backup power supply. Uninterruptible power supply for video surveillance.

In addition to connecting the power supplies of the cameras to the emergency power supply circuits in the building, you can also “secure” in one of the following ways: connecting to a UPS or using the built-in battery.

Using AC or DC to power the surveillance cameras.

There was once a war of currents between Tesla and Edison. But our story is not about that))).

AC in CCTV is used to power cameras that are located at a farther distance from the power source.

24V 50Hz alternating voltage is most often used in traditional dome cameras, which have a fairly high consumption due to built-in electric motors, fans and heaters. Such cameras are quite expensive and the presence of a built-in power supply is imperceptible against the background of the overall price. From a voltage of 24V 50Hz, it is quite easy to obtain a constant voltage of the required quality inside the casing, while it meets the requirements of electrical safety. Although the factors of high cost of power redundancy and electrical interference from alternating voltage 50Hz remain in force.

Alternating voltage 220V 50Hz is often used to power box cameras placed in thermal housings with built-in power converters. Although there are cameras that are directly supplied with 220V, i.e. the power supply is built into the camera. Such a solution certainly has some advantages, the main one in my opinion is that such voltages are not joked, and system developers, willy-nilly, are forced to lay normal power supply wires without saving on copper. Well, this is more of a psychological factor, but there are enough minuses.

DC voltage 12V is supplied directly to CCTV cameras that do not have a transformer isolation from the power line as in the case of AC voltage, then remote outdoor cameras are more susceptible to induced voltages from atmospheric discharges (lightning). Here, the questions of lightning protection arise in full growth.

What is such a device

The poe injector is a device designed to supply power to an IP camera using a “twisted pair” cable. There is no need to lay a power cable. Two free pairs of wires of the network cable are used for power.

Voltage can also be supplied through wires that carry information.

Such devices can be of two types:

Active devices work with devices that support PoE and can extract power from the general flow. The voltage is supplied after agreement between the issuing and consuming equipment, which ensures the safety of the connection.

The passive injector is paired with a splitter. The first device is placed at the beginning of the network and is supplied with power. The second is at the end, acting as a stream separator. Further, the voltage is transmitted over a twisted pair.

The technology allows you to provide power to IP cameras when there is no 220 V outlet nearby. You can connect the device with your own hands. Poe switches can have up to 16 ports and can include multiple compatible devices that require power.

Technology advantages

The technology has many advantages that have led to the widespread use of poe switches for arranging video surveillance systems. Among them:

  • the connection diagram of IP cameras becomes simpler. There is no need for power cables connected to all devices, no bulky power supply is needed;
  • security. Poe power injectors transform 220V into the voltage required for the operation of video cameras. more often 12V;
  • the ability to increase the distance to the powered device;
  • the ability to control the device remotely. turn on, turn off, reboot, etc.

Another important advantage is that the cost of powering IP cameras over twisted pairs is less than using a standard power cable. Using a poe switch in the power supply of video cameras can save money and time.

Standards

Poe voltage transmission technology is relatively new. It was designed to supply power to switching devices that have their own IP set according to the IEEE standards. The IP camera can be powered via poe using the following devices:

  • swarm injector. Purpose. supplying voltage to the Ethernet network for supplying power to the device;
  • splitter. Purpose. the allocation of constant voltage from the flow. Most often it is 12 V. Helps to power devices that do not support PoE;
  • extension cords Purpose. to increase the distance over which information and voltage is transmitted over Ethernet. This is the best solution if the IP camera is far away — you can increase the line by 100-200 meters. Extension cords do not have their own power supply, they take part of the transmitted power.

Poe power transmission does not degrade the quality and speed of information dissemination.

The reason is the use of high frequency transformers. The voltage goes to the center taps and does not affect high frequency signals. The implementation of power supply over twisted pair depends on the pinout.

Many people who do not know what poe is, wonder why the ports of devices that do not support this technology are not burned. The devices are connected like this. Both of them, transmitting and receiving, are negotiated upon connection. It is established whether the technology can be used, and also the class of the device that accepts the voltage is determined.

Honda Grom T-Bolt Cam & Injector | How-To

If there is no support, the physical parameters will be different and no voltage will flow into the line. This is protection in case of accidental connection of switches for IP video surveillance, made by hand. The essence of the coordination is that a voltage of 3-10 V is applied to the wires, which helps to assess the characteristics of the terminal device and conclude whether it is compatible. The process lasts no more than 0.5 seconds.

READ  Doesn't Show Rear View Camera

If the parameters are within the required limits, the power class is set. Depending on the power supplied, poe switches for video surveillance are divided into the following classes:

  • 0. 15.4 W;
  • 1. 4.5 W;
  • 2. 7 W;
  • 3. 15.4 W;
  • 4. 30 W.

If, as a result of matching, an overload of current is revealed, the voltage from the wire is removed (in 0.5 seconds).

PoE injector and splitter for powering IP cameras from a distance

Digital IP cameras are becoming more common. One of the main areas of their application is video surveillance systems. An uninterruptible power supply is required for proper functioning of the video camera. There are several options for organizing power supply, one of them is poe injectors. They allow you to provide equipment with power over the network wire, because there is not always access to a 220 V outlet.

Main characteristics

The main parameters for choosing a poe switch for video surveillance are:

  • the number of ports, there are devices for 8 ports or more. There are poe devices with 16 ports, the choice is due to the number of connected equipment;
  • port speed. 10/100/1000 Mb;
  • port power. Is in the range of 15.4-30W
  • required power transmission distance for IP cameras.

It is important to correctly calculate the required power. For this, the total consumption of terminal devices should be estimated. It is advisable to do this with a margin. Next, you need to familiarize yourself with the specification of the switch, see how much power each of the ports provides. For example, 8 port. up to 7.5 watts. Estimated based on peak load.

Although the technology provides power transmission up to a distance of 100 meters, it is undesirable to use the maximum value. In practice, the line length should not exceed 85 meters. This will help get rid of the influence of factors that can negatively affect the quality of the transmission: pickup, wire bends, etc.

The technology was developed with the aim of reducing the cost of laying networks in offices and industrial enterprises. But soon it gained popularity among individuals, as it simplifies the connection of equipment.

Features of connection via Ethernet

In this case, the installation of video surveillance is performed using a cable. You will need a twisted pair with ready-made plugs. If multiple chambers are needed, use a crimping tool. The length of the cable can be adjusted by yourself. This allows you to make the connection neat, without unnecessary loops and hanging hanks.

When installing up to 5 cameras, one router is enough. If there are many video surveillance devices, a separate switch will be required. This situation develops at enterprises and on the territory of commercial facilities with a large area.

How to connect a CCTV camera

Infotech company offers modern security elements. In each case, the connection diagram of the video surveillance system is selected. As a result, you get an individual approach, wide service and regular equipment maintenance.

To organize reliable protection at any facility, modern and reliable video surveillance systems are needed. They provide year-round monitoring of the territory, allow you to monitor the situation in real time or make records. How to connect a CCTV camera?

Hardware connection

Depending on the camera model, it is important to select a power source and network outlet. IP cameras can be connected not only via the Internet. There are several options for connecting:

  • Ethernet. This is a standard twisted pair cable connection.
  • Wi-Fi. This is a wireless connection.
  • PoE. This is a cable connection that requires a dedicated injector and a separate lead wire.

Note! If the instructions indicate one PoE connection option, the camera will not work with a regular network cable.

Features of connecting an outdoor camera

Connection of IP video surveillance is possible if the camera needs to be located at a sufficient distance. Twisted-pair cable has limitations on the wiring distance. If this condition is not met, the signal is completely or partially muted. The camera will not be able to function in the same way as under normal conditions.

The same situation applies to power wires. The power of the voltage and chambers completely depends on their cross-section. Almost all IP cameras operate at a voltage of at least 12V.

Features of connection via Wi-Fi

An Ethernet connector is used for connection. After that, you need to go to the interface by the IP address of the equipment. The latter is indicated in the documents for the router. Then you need to go to the wireless network settings. You need to activate it, enter information about the Wi-Fi connection.

The device can be turned off. When reconnected, it independently finds the network and becomes available at the previously entered IP address. If the camera supports WPS technology, you must press and hold the corresponding button. After that, the search mode on the router is activated independently. The devices are connected in a few seconds.

Note! Manual data entry can also be used. In this case, you need to enter the camera PIN, which can be found on the box or in the documents.

Connecting analog video surveillance

The latest analog cameras are virtually indistinguishable from digital cameras. They have the same resolution, image quality, and additional functionality. Analog video control has AHD, HD-TVI, HD-CVI formats. At the same time, they fully compete with IP technologies.

It is important to know how to make a video surveillance connection in the presence of analog cameras. You can create a home control system or connect equipment in an office and commercial center. In this case, the connection is carried out directly to a personal computer or TV. No additional hardware required.
What cables are used when connecting

You must select a pin coaxial cable. This is a standard cable suitable for connecting the antenna to your TV. It is important to choose a quality product from reliable manufacturers so that the connection does not fail.

To connect the power supply, use the red cable. Two cables are used for RCA connectors. red for audio signal, yellow. for conducting a video signal. An additional black cable is provided for grounding the devices.

When connected to a personal computer, you can install special software. It allows you to set the correct time, issue an alarm message when motion is detected, or set a timer for the desired time period. This expands the functionality of the camera, tracking the situation around the perimeter and indoors.

The Infotech company provides services for the supply, installation, configuration and repair of video surveillance systems. The range of our company is a full range of equipment and software for digital video surveillance.

How to connect an injector for a video camera

PoE (Power-over-Ethernet) technology was created for IP telephony, access points, IP cameras and other devices to which it is undesirable to run a separate power cable. PoE technology does not affect the quality of data transmission, the potential of the Ethernet level is used, that is, network cables.

It is important to understand that a power supply device (such as a PoE router) will only supply power to the cable if the connected device (such as an IP camera) supports PoE. How does this happen?

1) First, a check is made: whether the connected device is powered (PD). A voltage from 2.8 to 10 V is applied to it, the input resistance of the connected device is determined. If the parameters correspond to the required ones, the power supply goes to the next step.

2) The power supply determines the power consumption of the connected device, for subsequent control of this power. Depending on the power, the devices are assigned a class: from 0 to 4.

How to use PoE injector to power your IP camera

After the device is classified, a voltage of 48V is applied to it with a rise time of no more than 400 ms, and the power supply begins to control its operation:

1) If the device consumes less than 5 mA for 400ms, then the power supply stops;
2) If the resistance of the connected device is greater than 1980 kΩ for 400 ms, the power supply is interrupted.
3) If the current consumption exceeds 400 mA for 75 ms, the power supply is interrupted.

PoE injector

There are two types of devices. PoE splitters and PoE injectors. We figured out the splitter, and how the PoE injector works?

For example. Let’s imagine that your infrastructure uses a switch without PoE support, the network cable only transfers data.

How to connect and supply power over twisted pair to devices supporting this technology in such a system? It is in such cases that a PoE injector is used, which serves to supply electrical voltage to the network cable.

PoE injector connects to both RJ45 and power supply. As a result, the injector receives data at the PoE input, and at the output. both data and voltage that can be used to connect devices that support this technology.

PoE. IEEE 802.3af

PoE adapter

It is an AC-DC converter with a built-in splitter and stabilizer at the output. The PoE adapter does not use phantom power, but uses free pairs (which means the inability to use gigabit ports, the inability to use two-pair cables, the inability to share the cable). The only difference from the splitter is that the adapter, by increasing the voltage, supports the line length up to 100m at rated power and activates the PoE power supply circuit. It is not a fact that the equipment that is powered by the PoE-B standard will work. That is, it uses the same 1, 2, 3, 6 contacts for power and data transmission.

PoE splitter

With this method of connection, it is necessary to carefully select the power of the power source and its consumer.

IEEE 802.3bt

  • A new standard IEEE 802.3bt has now been developed, this technology can power devices up to 51W over a single cable, in this case all four pairs of Category 5 cable are used. Using previously unused pairs of wires for power supply increases efficiency and power without any additional costs for cables.

Differences between PoE and PoE

Power Transfer Method PoEPoE
DC voltage range on the powered device 36 to 57 V (nominal 48V) from 42.5 to 57 V
Source voltage range from 44 to 57 V from 50 to 57 V
Maximum Power of PoE Source 15.4 watts 30 watts
Maximum Power Received by PoE Consumer 12.95W 25.50 watts
Maximum current 350 mA 600 mA
Maximum cable resistance 20 Ohm (for cat.3) 12.5 ohm (for cat.5)
Nutrition classes 0-3 0-4
READ  How To Make A Camera From A Phone

3 tips for choosing the right PoE switch from PIPL experts

A PoE switch seems like a pretty simple device. However, it is worth choosing it not only for the price and the number of ports for connecting cameras. So that the system does not fail at the most inopportune moment, it is important to take into account 3 additional parameters:

power. The switch must be able to meet the power requirements of the cameras. At the same time, it is important to correctly calculate the total power and lay 20-30% of the stock;
2. performance, outdoor or indoor. Depending on the location of the switch, its case can have both high protection according to the IP standard, or practically without it.
3. scope of application. Inexpensive PoE switches are commonly used in home systems and can only support low-resolution cameras. Professional models have a large number of ports and high total power.

Free yourself from unnecessary wires with PoE Switch for video surveillance

What is needed to ensure the operation of an IP video camera? That’s right, the power supply and the video signal transmission channel. Usually these are 2 different wires, the use of which imposes certain restrictions on the location of the camera, placing increased requirements on it.

PoE technology allows video and power transmission over a single FTP / UTP cable.

PoE switch functions in a video surveillance system

The main devices for ensuring the operation of IP cameras in a system with PoE communication technology are PoE switches. In appearance and basic functions, they are no different from standard switches. The only difference is the ability to transfer through the power ports to connected devices.

Depending on the models of PoE switches, both all ports and a certain group can have the power transfer function. Considering the fact that there are models with the number of ports from 4 to 24, one can imagine how much simplified the installation of a video surveillance system when using them.

With PoE Switch, it is very easy to integrate an uninterruptible power supply into your security system. It is enough to connect it to the switch and in the event of a power outage, the entire system will instantly switch to using reserve energy.

Free yourself from unnecessary wires with PoE Switch for video surveillance

Description of PoE technology and 4 advantages of its use in video surveillance

Power over Ethernet, or PoE for short, is a technology based on the IEEE 802.3af standard. Channel power can be up to 15.4W per port. Taking into account network losses, cameras can reach up to 13 W, which is quite enough to ensure the operation of both the device itself and the IR illumination. The maximum length of one communication channel cannot exceed 100 meters.

Based on these features, there are 4 main advantages of using PoE in IP video surveillance systems:

no need to lay an additional line of electrical wiring and install bulky power supplies. A small PoE switch handles the power supply of all connected cameras by itself;
2. there is no binding to the location of the camera;
3. Only 1 cable from the camera is easy to hide and easy to connect;
4.Real economy of finances and time.

Buy the original is reliable and profitable

Choose original equipment at an attractive price!

Power over Ethernet (PoE) for video surveillance

Power over Ethernet standard

In June 2003, the IEEE Institute released the IEEE 802.3af standard. Power over Ethernet (PoE). The current specification of PoE technology describes the operation of Ethernet equipment, which consists of two parts: an adapter-injector, which serves to inject power into the line, where data is transmitted using Ethernet technology, and an adapter-splitter (splitter), which separates digital data from the power supply and supplies them to two different outputs. In the IEEE 802.3af standard, an injector and / or Ethernet equipment that includes the function of introducing power into a cable is called Power Source Equipment (PSE), and a splitter and / or a device powered via an Ethernet line is called Powered Device (PD).

The standard provides for the supply of 48 volts DC voltage over the twisted pair and a maximum power consumption of 15.4 watts. This technology works with existing cabling systems, including Category 5 cables, without the need to make any modifications to the existing SCS (structured cabling network).

How PoE adapters work

Power over Ethernet technology does not affect the quality of data transmission. To implement it, the properties of the Ethernet physical layer are used:
A) Use of high frequency transformers at both ends of the line with a center tap from the windings.
A constant supply voltage is supplied to the central taps of the secondary windings of these transformers, and is also removed from the central taps on the receiving side. The use of central taps of signal transformers allows, without mutual influence, to transmit one pair of wires and high-frequency data and a constant supply voltage.
C) Using free pairs for power connection. Modern 100Base-TX Ethernet cabling consists of four pairs, two of which are unused.

Accordingly, there are two options for supplying power to PSE with a PoE adapter:
A. to twisted pairs that carry data (example), Fig. one
B. for unused pairs in the cable (example), fig. 2

As you can see from Figures 1 and 2 PSE PoE adapters (PoE injectors) differ, depending on options A or B, while splitters, i.e. PoE PD adapters are versatile. The PD PoE adapter must be able to accept power in any way, including when the polarity is reversed (for example, when a computer-to-computer crossover cable is used).
It is important that the PSE PoE adapter only supplies power to the cable if the connected equipment is a PD type device. Thus, equipment that is not PoE capable and is accidentally connected to the PSE adapter will not be damaged. The procedure for connecting and disconnecting power to a cable consists of several stages.

Connection definition phase.

The “connect detection” step is used to determine if the equipment connected at the opposite end of the cable is a PD device.
At this stage, the PSE PoE adapter supplies the cable with voltage from 2.8 to 10 V and determines the parameters of the input impedance of the connected equipment. For PD device. this is a resistance of 19 to 26.5 kΩ with a parallel connected capacitor of 0 to 150 nF. Only after checking the compliance of the input impedance parameters, the PSE PoE adapter proceeds to the next stage. the classification stage, otherwise the PSE again, after a time of at least 2ms, proceeds to the “connection definition” stage.

After the stage of determining the connection, the PSE PoE adapter can additionally perform the stage of classification. The classification stage is used to determine the range of power that the PD can draw in order to then monitor this power.
Each PD device, depending on the declared power consumption, will be assigned a class from 0 to 4. The maximum power range is class 0. Class 4 is reserved by the standard for further development.
A PSE PoE adapter can remove voltage from a cable if the PD device draws more power than it announced during the classification phase. Classification is done by injecting 14.5 V to 20.5 V into the PSE cable with a PoE adapter and measuring the line current.

Full voltage phase.

After passing through the PSE identification and classification steps, the PoE adapter supplies 48 V to the cable with a rise time of no faster than 400 ms.
After applying full voltage to the PD, the PSE PoE adapter monitors its operation in two ways.
1) If the PD device draws less than 5 ma for 400 ms, the PSE PoE adapter removes power from the cable.
2) The PSE adapter supplies the cable with a voltage of 500 Hz with an amplitude of 1.9. 5.0 V and calculates the input impedance. If this resistance is greater than 1980 kOhm for 400 ms, then the PSE PoE adapter removes power from the cable.

In addition, the PSE PoE adapter continuously monitors the overload current. If the PD device draws a current for 75 ms more than 400 mA. then PSE will remove power from the cable. Shutdown phase.

What is POE injector?

A POE injector is a device that supplies power to a network device over a twisted pair cable. Power and data are transmitted over the network cable at the same time.

POE injector is used when there is no access to a 220 V outlet nearby.

In addition, the installation of “twisted pair” is much cheaper and faster than the installation of a power cable. Therefore, using POE technology saves you money and time.

The POE injector has two LAN ports. One is signed “POE” and the other. “LAN”. A POE-enabled network device is connected to the POE connector, and to the LAN connector. computer, switch or router.

Conventional power supply with POE injector:

Power supply with built-in POE injector:

There is another type of POE. passive POE injectors. In fact, these are just special adapters that allow you to remotely power network equipment using a standard power supply.

Let’s take a closer look at passive POE injectors and where they can be used.

First example of a passive POE injector. MikroTik Gigabit PoE.

This passive PoE injector is used to remotely power devices with gigabit ports that support POE technology.

A standard power supply is connected to MikroTik Gigabit POE. The POE injector connects to a computer, router or switch. An Ethernet cable is connected to the LAN connector of the injector. On the other side, the Ethernet cable is connected to the LAN connector of the device with POE power supply.

There is another very interesting set of passive POE injectors. this is the Passive PoE ™ Set 5.5×2.1 (Standard). With this kit, you can remotely power up even a router that does not support POE technology.

A standard power supply unit, a switch and a twisted pair network cable are connected to one adapter. To the second adapter. the second end of the network cable. Also, the second adapter is connected to the LAN port of a device without POE support and to a standard power connector.

POE technology is a state-of-the-art technology that provides an alternative way to supply power to network devices. It allows you to solve the problems that arise when laying new Ethernet networks or upgrading old ones, and allows you to place CCTV cameras in places convenient for you. PoE-capable equipment is readily available, so it has gained a lot of popularity. PoE technology not only saves you money, but also time for the installation of network equipment.

BYRGPUB.COM 2021