Model number WJX-2/RJ45 Network unit Power unit Rated operating voltage Un 5V 12 twenty four 220 Maximum continuous operating voltage Uc 6V 15 30 320 The maximum discharge current Imax (8/20ms) 1-2 0.3KA 10KA 10KA 10KA 3-6 0.3KA 1, 2, 3, 6-PE 2KA SE-PE 5KA Limit voltage Up 10/700/ms 1-2 <20V 30V 60V 600V 3-6 <20V Insulation resistance MΩ ≥0.4 Insertion loss dB ≤ 0.5 Near-end crosstalk dB ≥60(PASS) Bandwidth FG (0.3~100)M Transmission rate Vs 100 M Response time Ta ≤1ns ≤25ns Enclosure rating IP20 Dimensions 90×66×28mm Housing material Shield metal aluminum Protection line pair 2 pairs (1-2, 3-6) Differential mode, common mode protection Interface mode RJ45 Terminals Model number WJZ WJZ Thunder current flow (In) 200KA 200KA Attenuation rate 8/20us 8/20us Steep attenuation factor 8/20 us 8/20us Wind strength 40M/S 40M/S Number of flashes Single needle Single needle Height (M) 1.0 1.5 Weight (KG) ≤3.0 ≤ 4.8 Flange size (mm) (Φ) Customized Customized Poly Resin Bathroom Accessory Sets Poly Resin Bathroom Accessory Sets,Bathroom Set Resin Bottles,Black Square Bathroom Set Resin Bottle,Blue Bathroom Set Resin Bottles MingHui Houseware Company Limited , https://www.minghuihousewareltd.com
Every year, various communications control systems or computer networks are damaged by lightning strikes. Occurrences of equipment damage due to lightning strikes and failure of automated monitoring often occur. Among the road monitoring subsystems, some of the front-end cameras are installed outdoors, and are prone to lightning damages in areas where thunderstorms occur frequently. Therefore, it is extremely necessary to provide lightning protection for these devices.
In the road monitoring system, the outdoor surveillance cameras distributed in various places, the AC 220V power supply passes through the two-core cable, the video signal passes through the 10Base2 thin cable with BNC connector, and the RS485 communication control signal passes through the multi-core cable and is transmitted to the central control host. , Conduct centralized monitoring.
In order to prevent induced over-voltage and over-current caused by lightning, appropriate surge arresters should be installed at both ends of the power line of all monitoring devices and the devices connected to the signal line. Front-end cameras in the surveillance system are generally divided into outdoor installation and indoor installation. The indoor camera signal transmission cables and power supply cables are routed through the "buried" method, and there is less chance of lightning strikes. When selecting the type of lightning protection device, it must be noted that the lightning protection device must meet the following basic requirements:
1) In normal operation, the lightning protection device shall not affect the normal transmission of the signal. The impedance of the lightning protection device to ground shall be as large as possible, and the impedance in series in the circuit shall be as small as possible.
2) When the lightning strikes the communication bus, the lightning protector should exert a good voltage clamping effect, and the clamping voltage should be lower than the RS485 chip's withstand voltage level.
3) The lightning protector itself should be intact during the suppression of the lightning strike that does not exceed the maximum flow of the arrester.
4) Lightning protectors should have sufficiently fast response to lightning strikes.
Second, the overall monitoring system lightning protection program
1. Direct lightning protection The simple method of lightning protection is to use lightning rods. Since the outdoor spherical cameras are located outdoors and are far away from each other, the outdoor cameras must be designed and installed with lightning rods. The specific design scheme is as follows: Install a lightning rod on the poles of the outdoor spherical cameras (on the top of the pole), the specification is φ16×1000mm galvanized round steel, and the installation method is welding.
2. Lightning protection grounding requirements Lightning protection grounding is composed of lead wires, grounding wires, and grounding bodies. The down conductor is the channel that guides the lightning current from the lightning rod into the ground. The grounding body is buried in the ground and connected to the down conductor, and the lightning current is discharged to the ground. The grounding body meets the requirements of the grounding resistance. When the distance between multiple grounding bodies cannot be greater than 20M, a grounding net isolator must be installed. The grounding wire generally uses 40×4mm galvanized flat iron or more than 25mm2 insulated copper wire, one end is welded to the grounding body, and the other end is led to the equipotential connection row in the room. The grounding body and the down conductor or the grounding wire are generally made of lap welding. The welding place must be firmly welded without welding. At the same time, in order to ensure that the grounding resistance is not more than 4Ω, the grounding body must be reliably connected to the foundation grid of the building. For the monitoring center and the camera close to the building, we designed the joint grounding method using the main steel reinforcement of the building. For the camera far from the building, we need to make a set of artificial grounding body beside the camera. The specific ground network design scheme is as follows.
3. Lightning protection of the power supply system The main energy of the lightning shock wave is concentrated from the tens of Hertz to the lower end of the power of several hundred Hertz. Therefore, the energy of the lightning shock wave is easily coupled with the industrial frequency circuit and the resonance occurs. Therefore, the lightning shock wave comes from the power supply. The probability of a line entering an electronic device is much higher than the probability of entering it from a signal line. According to statistics, about 80% of lightning accidents that damage electronic devices are caused by power lines. Therefore, the power supply of devices in the system should be particularly strengthened. Lightning protection measures.
1) Install the first-level reinforced power source lightning protection device at the main distribution cabinet of the control building;
2) Install a second-level standard power source lightning protection device at the control system distribution box of the central control room;
3) Install a standard power supply lightning protector at the entrance of the outdoor PTZ camera power supply;
4) outdoor fixed camera, install standard power supply lightning protection device;
4. Lightning protection for video signal lines and PTZ control lines The main considerations when selecting these arrester types are:
1) The response time is less than 10ns;
2) Limit voltage below 50 volts;
3) The attenuation of the signal after access is between 0.1dB-0.8dB.
Third, lightning protection device selection
Network combo lightning arrester model: WJX-2/RJ45
(Network + Power) Two-in-one lightning protection device 
1. Overview This surge protector is designed according to the national standard GB/T18802.21-2004/IEC61643-21:2000.
2.Feature It is suitable for the monitoring system front-end network camera, wireless remote control camera power line, network cable lightning surge protection, so that it is protected from damage caused by induced overvoltage, operating overvoltage and electrostatic discharge, etc.; The lightning protection of signal power supply with different voltage levels. The characteristics of the entire product are: multi-level protection, large flow capacity, low limit voltage, fast response time, low insertion loss, and high transmission rate.
3. The use of ambient temperature: -40 °C ~ 70 °C; relative humidity: ≤ 95%; atmospheric pressure: 70kPa ~ 106kPa.
4. Working principle The surge protector is connected in series with the front end of the protected equipment. When the transmission line is subjected to induced lightning and other transient over-voltage surges, the inrush current is discharged to the earth through the protection branch of the surge protector. The sense overvoltage is within the allowable voltage range of the device, thus ensuring the safety of the operating device.
5. Technical indicators
6 Installation, use and maintenance 6.1 Installation instructions 6.1.1 Before connecting the protector to the system, first check the grounding resistance of the grounding network and meet the requirements of the specification.
6.1.2 Connect the protector to the front of the protected equipment and it must be connected reliably.
6.1.3 Connect the ground wire of the protector as short as possible to the protective grounding busbar of the equipment room.
6.2 Precautions 6.2.1 There are input (IN) and output (OUT) marks on the protector. The output terminal is connected to the protected device. Do not connect it reversely. Otherwise, the protector may be damaged and the device cannot be protected.
6.2.2 If the loss increases due to factors such as poor connector connection, the protector should be reconnected or replaced.
6.2.3 Users are not allowed to disassemble the fasteners of various parts of the protector, so as to avoid damage and affect normal operation.
6.3 Check of the protector 6.3.1 The protector does not require special maintenance. If the protector is damaged by high voltage and lightning, (when the LED indicator goes off, it means that the lightning protection function has been lost). The protector should be replaced.
6.3.2 Use the three-meter meter “Ω×1†to measure the corresponding input of the network signal. The output resistance is about 4.7Ω. If the resistance is too large and abnormal, replace the protector.
6.3.3 Use the “Ω×10K†file of the three-meter table to measure the resistance of the network signal line to the ground, which is about 400kΩ. The resistance of the line to the ground and the shell to the ground should be infinite. If the measured resistance does not match, protectors should be replaced.
7. Product appearance and wiring 
Monitoring pole lightning rods Wanjia series single-pin lightning arrester is a non-inductive, low-impedance metal inner conductor down conductor, which transmits the lightning current after receiving the lightning to the earth and makes the protected antenna tower or building Things do not live. In most cases, the impact of the electrostatic field cable is less than 1/10 of the impedance of the tower to allow the protected equipment to reduce the risk of counterattack and induced overvoltage.
Application scope:
Monitoring system, camera support bar, petrochemical warehouse, gas station, building building, beacon station, communication base station, meteorological station, military base, radar room, bank building, etc. 
Monitoring system (pole) lightning protection design
I. Overview