Any user has recently had the information firmly stuck in his head that IP video cameras are much better than analog ones. This article will discuss the principle of connecting both IP and analog models.
After all, only a few years ago analogue high-definition cameras appeared. These are AHD, CVI and TVI formats. In terms of resolution and picture quality, they are practically not inferior to the IP format, and the cost is several times cheaper.
As a rule, these are 1 or 2 Megapixel cameras. Their price segment is from 1000 to 2500 rubles. Moreover, if you already have an analog system installed and you just want to expand the number of cameras, or replace burned out ones, now it’s enough to buy modern inexpensive models with an OSD menu. 
They have a switch on the shank that allows you to switch them to analog PAL mode.
Installation of video surveillance with analog cameras
Before you directly install video surveillance in your home, you need to draw on paper the locations of video points, cable laying locations, etc. 
In order to maximize coverage of the entire space around the house, it is necessary to install at least one camera on each wall. It wouldn’t hurt to put another one on the roof in front of the front door.
Video surveillance materials
Here are all the materials you will need to install an analog video surveillance system:
- cable for powering the entire system from a 220V network
It is best to use the VVGnG-Ls 3*1.5mm2 brand. 
- wires for switching in low-current switchboard - PUGV 1.5mm2
Do not confuse with KVK-V. The KVK-P brand is an outdoor option, and KVK-V is for installation inside the house. It is not UV protected. 
- 3-core PVA wire cross-section 1.5mm2
First check that the number of video inputs on it is equal to or greater than the number of cameras.
- computer HDD for storing and recording video
The minimum recommended volume is 1TB. You can use both large 3.5-inch and small 2.5-inch disks. Small drives are much quieter and generate less heat. 
- power unit
For example, the same as used to connect LED strips. A standard power supply with a cable cross-section of 0.75 mm2 is enough for high-quality signal transmission over a distance of no more than 500 m. 
Select the power of the unit according to the same principle as for LED strips. That is, the total power of all cameras + 30%.
They are needed to connect the cable to the camera itself and connect to the video input of the recorder.
If you don't want all your video surveillance to burn out in the first thunderstorm, don't skimp on this piece of protection.
It is most convenient to connect a DVR or UPS via a plug and socket. Please note that all these materials must be compatible with each other. Simple IP equipment will not work with analog equipment and vice versa.
You can choose ready-made video surveillance kits, or individual components - cameras, video recorders, cables, connectors, plus you can get acquainted with the current prices today.
220V power connection in the low current cabinet
The low-current switchboard, where the DVR, power supply, etc. are located, may be located in a different room from the general 220V switchboard, sometimes even in the garage or basement.
Therefore, the first thing you need to do is supply electricity there.
Ditch the walls and lay the VVGnG-Ls 3*1.5mm2 cable from the 220V switchboard to the low-current cabinet. You power it from a separate modular circuit breaker with a rated current of 10A. 
In a low-current panel, connect the power cable to the terminals of another circuit breaker. It will be an introductory one for this cabinet. And directly from it you connect modular sockets and a surge arrester. 
The arrester is connected according to the diagram below. The white and brown wire is the phase, the blue wire is the neutral wire, and the yellow-green wire is the ground wire. 
Connecting sockets: 
In the same cabinet there are:
- power unit
- DVR + 1TB disk
- UPS
The hard drive is mounted in the recorder itself. To do this, unscrew the screws and disassemble it. There should be a space inside for the hard drive. 
Connect the connectors, and then screw the drive into place.
Please note that often the DVR case is also a cooling radiator for the disk.
Next, you power the UPS from the sockets through a regular plug. Most power supplies come without wires with a plug included, so here you will have to do it yourself. Use PVS wires and a regular Euro plug. 
Mount a plug on one end of the wire, and strip the other and connect it to the unit at the 220V power terminals, designated L and N. 
There is no particular difference in phasing or polarity where to connect zero and phase. Next, connect power to the video cameras. 
If there are not enough 12V output terminals on the unit, it is best to use terminal blocks. Set them according to the number of cameras and label the pins as “+V” and “-V”. 
Then, using PuGV wires, connect the 12V +V and -V output terminals from the power supply, with the corresponding connectors on the first terminal block. 
It is better to use red wires for the positive wire, and black wires for the negative wire. The remaining terminals are powered by jumpers. 
Installation and connection of cable KVK-P
Now you need to lay the KVK-P cable to each video camera, or rather to the place where you planned to place them. You can lay it indoors either in a plastic channel or simply on top of the walls.
On the street, if desired, it can be protected with corrugation, but not necessarily. 
To protect the connection points between the cable from the recorder and the cable from the camera from snow and rain, mount a junction box on the wall and route the wires into it. 
Next, remove the top layer of insulation from the cable, about 8-9 cm, and strip the two power cores. Press them with NShV tips. 
Insert these wires into the male power connector. There are two connectors "+" and "-". As we already agreed before, the red wire will be the positive contact, the black wire will be the negative one. 
After this, remove the insulation from the coaxial cable.
Carefully move the outer copper braid back so that not a single hair has accidental contact with the core in the center. Otherwise, the quality of the picture will be poor, or there will be no picture at all.
Expose the central core by 3-4mm and mount the BNC-F connector. 
Insulate everything from above with a protective cap. 
Connect the connectors together and close the lid tightly. 
To prevent moisture from getting inside, it is necessary to use a box with sealed cable entries on the sides. 
All other video cameras on the walls of your house are connected in the same way. To each of them you will have to pull a separate KVK-P cable. 
Connecting wires on the DVR
Now all the video surveillance cables need to be disconnected in the low-current cabinet. First, connect the DVR itself via the source uninterruptible power supply.
Then you strip the second ends of the KVK-P cable, brought into the cabinet, in the same way as shown above. In this case, connect the power wires (red and black) to the corresponding terminal blocks “+V” and “-V”. 
And insert the end of the coaxial cable, with the BNC-F connector installed, into the free socket of the DVR. Where it says Video In. 
Do the same with the remaining video cameras. 
All you have to do is set up the video surveillance by connecting the monitor to the recorder via VGA or HDMI connectors.
If the low-current cabinet is located far from the computer, you can use a laptop to configure it. And after that, output the signal to the monitor using a separate cable.
To safely use the monitor for other purposes, you can connect a computer to the HDMI connector, and cameras to the VGA connector. Then by changing modes you can easily switch pictures from different sources.
All software To set up video surveillance, it must be included with the video cameras. If for some reason it is not there, then you can try universal software, for example from ivideon.
Connecting IP CCTV cameras with PoE
To mount and install IP cameras, in addition to the materials indicated at the beginning of the article, you will need slightly different components:
The PoE function allows you to transmit both signal and power over the same cable through one connector.
Twisted pair is one of the types cable connection, through which data is transferred between the camera and the recorder in video surveillance systems. With its help, the signal is transmitted at high speeds, and the supply range without switching equipment significantly exceeds the same parameter for a coaxial cable. What are the features of video surveillance over twisted pair?
Principle of operation and features of operation
Data transmission over certain distances, regardless of the channel used, is subject to various interference. This interference gradually drowns out the useful information signal. When its strength drops to the level of interference, it is almost impossible to distinguish and isolate the necessary data from the general background.
The principle of operation of a twisted pair cable is a symmetrical line. In such connections, when transmitting data, interference is also transmitted symmetrically. And when they converge, their mutual destruction occurs, due to which the main data is easily recognized.
This principle of operation is ensured by the special design of the line, which, in addition to the cable itself, also includes a transmitter-receiver pair. Of this equipment, the transmitter is responsible for receiving and converting the video camera's unbalanced signal into a symmetrical one. Then it is amplified and sent to the receiver. At the receiver, the signal is re-amplified and converted back to single-ended form.
But this scheme also has a couple of nuances. Even this transmission method, although it allows you to neutralize interference, still does not exclude the weakening of the useful video signal. The transmission range in such systems is 50 Hz – 6 MHz. And since the channel capacity is much larger, the signal is supplied unevenly. Moreover, the higher the frequency of the transmitted video signal, the more it weakens. In addition, the degree of attenuation is also directly proportional to the range of the line used.
As a result, we can conclude that this transceiver format, also called passive, is suitable only for small cable infrastructures. Over longer distances, transmission is better achieved by active equipment. Such equipment includes various designs of jumpers or trimming resistors. With their help, two types of signal strength adjustment are carried out:
- Using a jumper – stepwise adjustment;
- Due to the resistor, the line is adjusted more smoothly.
The first type of equipment is quite easy to use. After calculating the total length of the line, jumpers are installed on precisely calibrated sections that amplify the signal. Of course, there is no need to talk about fine tuning here, but for most surveillance systems they are quite sufficient.
The tuning resistor is capable of providing more fine tuning. But this is only possible if additional equipment is used. However, not every master can adjust such a scheme.
By implementing the above measures and properly configuring the system, the signal transmission range over twisted pair cable can be increased from the standard 2 km to 3-4 km.
Features of choosing equipment for twisted pair
Effective work This type of device is only possible if the right components are selected. To do this, you should follow these tips:
- It is desirable that the receiver or transmitter include a protection unit against induced voltage or atmospheric electricity.
- The product in question must contain information about operating voltage, permissible temperature range, and compatibility with other types of equipment.
- If you plan to purchase an active transmitter and receiver, they must include controls for configuring the device.
- As a “plus” you can also consider marks such as characteristics of the protection system, frequency range and others. Of course, without proper qualifications, these designations will not say anything. But, on the other hand, they indicate the quality of the product.
- You should not believe statements such as “an image with 720p quality will not change even when transmitted over a couple of kilometers.” When transmitting twisted pair cables over such a distance, minor quality losses are an inherent factor.
- Also, when choosing a suitable version of a twisted pair cable, it is advisable to pay attention to its capacity. The option in which this value is lower will be more reliable and effective.
Connecting an analog video camera via twisted pair
Analog video surveillance over twisted pair is created by connecting transceivers to the line.
Connecting an analog video camera without transmitters even at a distance of 5 meters degrades the quality to the point of being unrecognizable.
A huge advantage of twisted pair over coaxial cable is the number of connected video cameras. Using one 4-pair Lan cable, you can fully connect 2 video cameras, i.e. simultaneously supply a signal and voltage.
Connecting an analog video camera via twisted pair cable is very simple. To do this, you need to decide on the color of the required pairs for connecting the transceiver and power plug on the video camera side and duplicate the sequence at the end of the line on the video recorder and power supply side.
The voltage supply via twisted pair is correct over a distance not exceeding 30 meters. As the distance increases beyond 30 meters, a voltage drop will begin due to the small cross-section of the cable.
How to connect an IP camera via twisted pair
To connect an IP video camera, rg45 connectors are used. Twisted pair cable for IP video surveillance can be either 2-pair or 4-pair. To connect any IP camera, two pairs of Lan cable are enough. Do not believe if anyone says that signal transmission will be better with a 4-pair cable.
Ethernet technology allows you to operate at speeds of 100 Mbit using only two pairs LAN cable, this is enough for any IP system. Compressing the connector into 4 pairs makes it possible to operate at a speed of 1 Gbit, which an IP video camera will never need.
When connecting a video camera over short distances, it is wiser to compress 2 pairs for the signal and use 2 pairs for the voltage supply.
To connect an IP video camera over long distances (for example, up to 150 meters), you can use a POE injector. To power the video camera via POE, you need to crimp 4 pairs under the connector.
The maximum operating distance of an IP video camera over twisted pair cable without a poe injector does not exceed 100 meters. To increase the operating distance of the IP video camera, you need to install an Ethernet extension cable for every additional 100 meters.
Standards and typesPoE
Today there are several types PoE technology and they are all significantly different. The reason for this is the following. When IEEE finally decided to move to standardize PoE technology, a long time had passed after its introduction, and many corporations had already developed and implemented their own PoE solutions. As an example, Cisco introduced the implementation of power over twisted pair back in 2000. But even after the standardization of IEEE 802.3af in 2003, and IEEE 802.3at in 2009, manufacturers continue to introduce new developments in PoE. Mainly due to the high cost of full-fledged 802.3af and 802.3at standards, while customers increasingly need budget solutions.
As a result, there are several PoE options:
- 802.3af standard,
- 802.3at standard,
- proprietary private standards, of which the most famous in the world is Passive PoE.
802.3af and 802.3at refer to active PoE, while Passive PoE is passive.
The implementation of food itself network cable(twisted pair) differs in the type of pinout. And depending on the voltage per port, PoE is divided into classes.
All this must be indicated in the technical data sheet of the device to be able to correct selection equipment.
Active standardsPoE - IEEE 802.3af and 802.3at
The main advantage of such PoE sources is their intelligent working diagram, which helps equipment work longer, save energy and avoid breakdowns.
So, before supplying power to the desired device, the active PoE source of the 802.3af/at standard itself (can be an adapter or switch) checks and finds out the following:
1. Does the device support PoE technology? If it is absent, electricity simply will not be supplied over the twisted pair.
2. Check what voltage the device consumes. And after setting the power class, it will supply only the required voltage value to the connected port.
3. Does the device need power and is it turned on? If the answer is no, power is not supplied via the cable.
4. Has the device been rebooted? If the answer is positive, the power is stopped.
Padimensions
Nutrition classes
The most common today is the 1st nutrition class.
Passive PoE
Passive PoE is a significantly cheaper analogue of the 802.3af and 802.3at standards. Passive power can significantly reduce the price of equipment. But at the same time, such equipment does not check the device requiring power via twisted pair cable for power consumption and its condition. That is, the voltage is simply supplied constantly. There is a risk of equipment incompatibility, which will either lead to immediate failure or the device will break down a little later due to overheating of the boards and their burning.
Leading manufacturers are adding Passive PoE technology in the form of useful functions. Let's give an example of a MikroTik device with PoE out. This PoE out can detect whether a device is connected to the port, and also knows about a short circuit or reboot. Some other MikroTik devices allow you to control these functions. You can turn PoE on and off on ports, change modes, and so on. Only in in this case We are not talking about ordinary PoE cords, but about PoE technology in routers, switches and other equipment.
Passive PoE sources vary in power, current, and voltage. Most often, manufacturers make them directly for their specific equipment. For this reason, the PoE source must be selected specifically for a specific device.
Pinout types
There is also a pinout of the third type, that is, when each core of a four-pair cable is used to supply power. But such pinouts are rare and only in proprietary PoE implementations. The best example will be UPOE from Cisco.
If at both ends of the network you install network equipment that supports the 802.3af or 802.3at standard, then in this case the type of pinout is not actually important, since the installed PoE consumer device will work with any of them. But if the standards are different, then this is important.
PoE cable
The quality of PoE is highly dependent on the quality of the cable and the length of the twisted pair. The twisted pair should be chosen as follows:
- there must be four pairs, that is, four pairs twisted pair and not lower than cat.5e;
- the twisted pair must be copper, not copper-plated;
- the thickness of the conductors must be at least 0.51 mm (24 AWG);
- the resistance in the conductors should not be higher than 9.38 Ohm/100 m (if more, there will be a large loss of power);
- preferably from a well-known manufacturer.
Our manufacturer's products are perfect. They make unshielded outer cable and shielded inner cable. By the way, we note that the use of shielded cable must be verified according to the specifications of any manufacturer. For example, PoE standard 802.3af or 802.3at in some equipment models can only be used in conjunction with unshielded twisted pair cable.
PoE length
The 802.3af and 802.3at standards indicate that the twisted pair length for PoE is exactly 100m. But in practice, the maximum length of a twisted pair cable will depend on many factors. And all these factors may be unknown in advance:
- conductor cross-section;
- metal conductors;
- presence of bends in the line;
- unevenness of the twisted pair, cable kinks, etc.
But if it’s Passive PoE, then the length should be no more than 30-60m. And it is necessary to calculate the line, taking into account the following:
- voltage consumed by the device taking into account peak load;
- voltage supplied by the source;
- the resistance of the twisted pair itself and the amount of voltage loss in this line.
PoE Power Budget
To calculate the PoE budget you need:
1. Calculate the total power of all PoE consumers without exception on the serviced line. You need to calculate based on the peak load of each device and take into account each operating equipment module.
2. Based on the power indicator, select a PoE source. In this case, it is necessary to pay attention to the power of individual ports, that is, which device will be connected to which port in the future, and also take into account the total power of the source, so as not to exceed the total power of consumers. And it is advisable to add 25% for reserve. Long-term operation of the line assumes that the power supplied by the PoE source will lose about 10% annually.
3. Take into account the power loss due to the length of the cable from the source itself to the consumer directly. The main thing here is the resistance of the conductor. In addition to the default values, do not forget that resistance increases when the cable heats up.
Network devices differ from other types of cameras, which are only elements of television surveillance systems. Such a device is completely complete and can independently record, digitize, compress and transmit a video signal over the Internet. It can be installed in any in the right place and receive an image where it is convenient - for this purpose. As with all complex electronic products, which are subject to strict requirements for operational reliability, uninterrupted power supply to the IP camera is required during operation.
Power supply features of IP cameras (twisted pair, etc.)
Having a high resolution, video clarity, these digital devices, and in fact mini-computers with a camera, require significant consumption electric current. Therefore, the organization of power supply for IP cameras must be approached with all responsibility to eliminate any malfunctions and technical failures.
Types of television surveillance systems
Depending on where the cameras are installed, there are 2 types:
- Video surveillance systems in buildings and premises with heating and lighting systems.
- Video surveillance outside buildings.
Naturally, equipment installed outside consumes a lot of power, which is usually used for IR illumination at night and heating the camera’s thermal casing at low air temperatures. In addition, in both cases, many cameras are equipped with rotating mechanisms with electric drive, motion sensors, which also requires costs.
Types of food
There are 2 power options:
- WITH laying a separate line from external unit power supply with a voltage of 5–24 V or from the built-in 220 V (for cameras for outdoor installation). But you will also need an Internet connection, which is generally reminiscent of double laying the power and coaxial cables to analog cameras.
- IP camera power supply over twisted pair by technology PoE. Only one wire is used to transmit power, video and control the device, which is convenient and practical. The most commonly used wire is 4 twisted pairs.
The big disadvantage is the wire length limit of 100 m. To overcome this limit, several have been developed technical solutions using additional equipment:
- Using PoE repeaters. Such a device receives power and data flow, then transmits it. A chain of such repeaters connected one after another significantly increases the distance and the ability to power an IP camera via PoE. It is advisable to use high quality cable to reduce losses.
- Installation of converters made using VDSL2 technology. These devices provide power supply up to 1.5 km.
- The use of “PoE Extender” technology, which allows the use of the “Power Reach” device to install cameras up to 500 meters, providing power to both the IP video camera and for power supply to the thermal casing, the use of IR illumination of video surveillance devices outside buildings.
In each specific case, it is necessary to take into account the situation as a whole. Effective choice will be influenced by many factors: availability and ramifications local network, condition and stability of power supply, lighting of premises and territory, climatic conditions, security regime and much more. It is advisable to entrust the development of design and technical solutions to specialists from organizations involved in the design and installation of television surveillance systems.
This will ultimately make it possible to create a balanced system, where all points of the customer’s technical specifications will be taken into account, including ensuring reliable power supply for IP cameras at a protected facility.
Power supplies
The quality of power supply usually leaves much to be desired. No consumer is immune from sudden power surges or unscheduled outages. Therefore, the correct choice of equipment is very important, because the reliable and long-term operation of any camera directly depends on a stabilized (constant voltage) and continuous power supply. A power supply that is of poor quality or does not meet the technical parameters may well render the camera unusable until it becomes necessary to replace it and render it unsuitable for repair.
You can use the power supply for IP cameras that provides the required technical parameters. The following requirements must be taken into account. In addition to the possibility of continuous operation, the power supply must be stabilized and protected from short circuit and overloads.
Taking into account the inevitable losses, the power supply must provide a 20–30% current reserve to compensate for them.
Powering an IP camera over twisted pair cable makes it much easier to organize power backup than when using analog video cameras. It is enough to connect the uninterruptible power supply to the PoE switch, to which all IP surveillance cameras are connected. This scheme most simply provides reliable uninterrupted power supply. There are switch models with a built-in UPS.
You should not save when purchasing a unit, since in addition to ensuring reliable operation of the cameras, it itself must be safe and not cause a fire or fire. It is better to purchase equipment from the manufacturer, official dealers or specialized organizations involved in the installation and sale of security system equipment.
Power supply for standalone cameras
In some cases, in the absence of a permanent power supply or temporary unstable power supply to remote or under construction objects, they are used. In such cases, it is necessary to calculate the battery capacity of the power supply to ensure the required operating time. It also makes sense to connect a motion sensor to save energy, which is important if there is no power supply to the facility.
It is best to select a suitable power supply for IP cameras from the camera manufacturer’s catalog, which will provide a ready-made solution, or entrust the selection of appropriate equipment technical specifications specialists.
In conclusion, it should be said that the choice of IP cameras today is quite justified, since technical specifications and technological solutions they are far superior to analog devices. Initial high price one product pays for itself due to the absence of many inevitable costs during installation and operation analog systems, and the benefits are undeniable.
In June 2003, the IEEE released the IEEE 802.3af standard - Power over Ethernet (PoE). The current PoE technology specification describes the operation of Ethernet equipment, consisting of two parts: an injector adapter, which serves to introduce power into the line where data is transmitted via Ethernet technology, and a splitter adapter (separator), which separates digital data from the power supply and supplies it 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 device powered via an Ethernet line is called a Powered Device (PD).
The standard provides for a 48-volt constant voltage supply over a twisted pair cable and a maximum power consumption of 15.4 watts. This technology works with existing cabling systems, including Category 5 cables, without the need for any modifications to the existing 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) The use of high-frequency transformers at both ends of the line with a central tap from the windings.
The 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 both high-frequency data and constant pressure nutrition.
B) Using free pairs to connect power. Modern 100Base-TX Ethernet cabling consists of four pairs, two of which are unused.
Accordingly, there are two options for supplying power to the PSE with a PoE adapter:
A - on twisted pairs along which the data goes (), Fig. 1
B - to unused pairs in the cable (), fig. 2
Rice. 1 Power over Ethernet (Option A), power supplied via data pairs (pins 1,2 and 3,6)
Rice. 2 Power over Ethernet (Option B), to unused pairs in the cable (pins 4,5 and 7,8).
As can be seen from Figures 1 and 2, PSE PoE adapters () differ depending on options A or B, while splitters, i.e. PD PoE adapters are universal. The PD PoE adapter must be able to accept power in any variant, including when the polarity changes (for example, when a computer-to-computer crossover cable is used).
It is important that the PSE PoE adapter supplies power to the cable only if the connected equipment is a PD type device. This way, non-PoE equipment accidentally connected to the PSE adapter will not be damaged. The procedure for applying and disconnecting power to the cable consists of several stages.
Connection definition stage.
The “connection detection” step is used to determine whether the equipment connected at the opposite end of the cable is a PD type device.
At this stage, the PSE PoE adapter supplies the cable with a voltage of 2.8 to 10 V and determines the input impedance parameters of the connected equipment. For a PD device, this is a resistance from 19 to 26.5 kohms with a parallel connected capacitor with a capacity 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 2 ms, proceeds to the “connection determination” stage.
Classification stage.
After the connection detection stage, the PSE PoE adapter can optionally perform a classification stage. The classification step serves to determine the range of power that the PD device can consume so that it can then control that 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.
The PSE PoE adapter can remove the voltage from the cable if the PD device begins to consume more power than what it declared during the classification phase. Classification is performed by introducing a voltage from 14.5 V to 20.5 V into the PSE cable with a PoE adapter and measuring the current in the line.
After the connection detection stage, the PSE PoE adapter can optionally perform a classification stage. The classification step serves to determine the range of power that the PD device can consume so that it can then control that power.
After passing through the PSE definition and classification steps, the PoE adapter supplies the cable with a voltage of 48 V with a rising edge no faster than 400 ms. In addition, the PSE PoE adapter continuously monitors the overload current. If the PD device draws more than 400 mA current for 75 ms, the PSE will remove power from the cable.
Once full power is applied to the PD device, the PSE PoE adapter monitors its operation in two ways.
1) If the PD device consumes less than 5 mA current 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 resistance. If this resistance is greater than 1980 kOhm for 400 ms, then the PSE PoE adapter removes power from the cable.
After passing through the PSE definition and classification steps, the PoE adapter supplies the cable with a voltage of 48 V with a rising edge no faster than 400 ms. Once full power is applied to the PD device, the PSE PoE adapter monitors its operation in two ways.
When FSE PoE adapter will determine that the PD device is disconnected from the cable or there has been an overload of the consumed current, the voltage is removed from the cable in a time of no less than 500 ms.
Benefits of Power over Ethernet
Power over Ethernet is an attractive alternative way power supply network devices. Moreover, its use is possible both when organizing new networks and when upgrading existing ones. Most often, when upgrading a network, it is necessary to install active equipment exactly where there is no power source or electrical outlets nearby. Thanks to the IEEE 802.3af standard, it becomes possible to install equipment in the most suitable locations, regardless of the lack of electrical wiring. For example, Wi-Fi point access can be placed in place best regards signal, even if there are no electrical outlets, or install it in any place convenient for viewing. PoE not only allows you to significantly save on the cost of power cables and other components, but also reduces the installation time of Ethernet equipment.