article POE on the knee (ammo1.livejournal.com/1047470.html) I talked about the different ways to connect the power CCTV cameras via LAN cable. I spent a little experiment.
Dome Camera AZISHN (Ammo1.livejournal.com/1053037.html) It will be powered by a 50-meter cable Proconnect 01-0045-3 (Ammo1.livejournal.com/1063728.html). Not to cut 50 meters of cable, I locked the 4 wires into the 100 meter bay. The resistance line of the four wires got 5.6 ohms, the second - 5.7 ohms.
The total resistance of the supply lines of 11.3 ohms. The same resistance will be in the lines of the two connected in parallel, wiring length of 50 meters.
All the experiments I carried out at a voltage of the power supply of 12 volts (standard voltage camera power) and 13.5 volts - a voltage which gives BBP (ammo1.livejournal.com/1043712.html).
Consumed currents measured in two modes - the day and night (included infrared light).
I used to pay a higher voltage StepUp XL6009E1 and lowering the cost StepDown voltage LM2596.
Experiment 1. Power supply - camera (camera is connected directly to the power unit).
Hereinafter: the power supply voltage - the voltage at the camera in the day mode, the current in the day mode / chamber voltage in the night mode, the current in the night mode.
12.0 V - 12 V 102 mA / 399 mA, 12 V
13.5 - 13.5 92 / 13.5 387 mA
Experiment 2. Power supply - Cable - camera.
12 - 10.61 The 117 mA / 260 mA in 8.96
13.5 - 12.32 V / 101 mA / 326 mA in 9.71
Experiment 3. Power supply - Cable - StepUp - a camera.
As many commentators have written, this option does not work. Though on StepUp output multimeter in day mode and shows a 12 volt, the camera is not started. Apparently, the power fails for a short time, making it impossible to operate the camera. In night mode, the voltage drops on the camera to 9.24, and it also does not work.
Experiment 4. Power supply - StepUp - Cable - camera.
On StepUp module exhibited voltage 14.6 V. It is chosen so that in the day mode voltage does not exceed the camera 13.5 V.
12 B - 13.51 In 131 mA / 490 mA At 10.14
13.5 - 13.52 V / 115 mA / 433 mA 10.13
Unfortunately I could not find out the information, a range of operating voltages from Chinese cameras (camera manufacturers and write modules 12 V, without specifying the range). It would be possible to raise the voltage to the cable so that it is 12 volts and backlight in night mode, the camera worked full power, but in the daytime the camera mode will be greater than 15 volts, and a voltage is allowed unknown or camera It burns. I did not try.
Experiment 5. Power supply - StepUp - cable - StepDown - camera.
Maximum input voltage StepDown-module 35 volts, so I put on the StepUp 35 volts.
12 - 12.00 195 mA / 612 mA 11.97 in
13.5 - 12.00 V / 173 mA / 540 mA At 11.97
This method of feeding most correct - it when the voltage on the cell is always stable, the cable losses only increase the overall current consumption. This mode is the closest to the "real POE".
Disadvantages of this method - you have to "pile up" two modules at both ends, consumption increases significantly.
conclusions
If the camera power source is used with a supply voltage of 13.5 volts (e.g. BBP) can be do without conversion, connect the unit even after a long cable resistance. The night mode is 9.7 volts per cell, light is on, but not bright. However, very often the brightness of IR illumination greatly excessive. Bonus - the current consumption is quite low, and when a large number of cameras required less powerful power supply.
If the brightness is not enough, it is necessary to set the voltage converters. The best option - to increase the voltage to 35 volts to the cable, and then drop it after the cable. The backlight will operate at full capacity, but the camera's consumption will increase by 1.5 times, and therefore the power supply unit will have to rely on the basis of the increased consumption.
There are a compromise - using one StepUp converter to increase the voltage to the cable in such a that, in the day mode it was no more than 13.5 volts per cell (in my case it was necessary to raise 14.6 volt). In night mode, wherein the camera is approximately 10.1 volts, and back light is already more or less clearly. Total consumption will increase with less than a quarter.
Of course, many will say, why the farm, when you can just buy a camera with POE 48V and do not fool yourself down. Of course, you can do so, but each camera will cost at least $ 3 more expensive It needs very expensive POE-switch, and any problems with the organization of power besperebeoynogo such a system. I for myself have chosen a cheap option, but you really decide. :)
© 2019 Alex Nadozhin
The main theme of my blog - Equipment for human life. I write reviews, share experiences, talk about all sorts of interesting things. My second project - lamptest.ru. I test LED lamps and help figure out which ones are good and which are not.