In the wiring project of the monitoring system, it is very common to lay the strong power line and the monitoring tv wiring harness in parallel, but the interference problem caused by this cannot be ignored. The strong power line will generate an electromagnetic field when it is running, and the monitoring tv wiring harness is responsible for transmitting weak current signals such as video and audio. Once the two interfere with each other, the monitoring screen may have problems such as snowflakes, horizontal stripes, and flickering, which seriously affect the normal use of the monitoring system. To solve this problem, it is necessary to consider comprehensively from multiple aspects and take effective prevention and treatment measures.
First of all, reasonable planning of wiring is the basis for avoiding interference. When designing the wiring plan, try to keep a certain distance between the strong power line and the monitoring tv wiring harness. The intensity of the electromagnetic field will weaken as the distance increases, so the greater the distance between the two, the less likely it is to interfere. In the actual construction process, independent wiring channels should be planned for strong power and weak power respectively according to the structure and layout of the building. For example, in the vertical shaft of the building, special strong power bridges and weak power bridges can be set up to let the strong power line and the monitoring tv wiring harness go their own way, reducing the chance of mutual interference from the source. At the same time, when planning the line direction, it is necessary to avoid long-distance parallelism between the two, and try to use a vertical cross-way to pass through, which can effectively reduce the degree of electromagnetic coupling.
Secondly, physical isolation is an important method to reduce interference. When the ideal spacing requirements cannot be met, physical isolation can block the propagation path of interference. Metal bridges are commonly used isolation tools. Strong power lines and monitoring tv wiring harnesses can be laid in independent metal bridges, and the two can be separated by metal partitions. Metal has good shielding properties and can absorb and reflect electromagnetic fields, thereby protecting the monitoring tv wiring harness from strong electrical interference. In addition, steel pipes or metal hoses can be used to protect the lines separately. The strong power lines are inserted into galvanized steel pipes, and the monitoring tv wiring harness is inserted into PVC pipes or metal hoses. The two pipes are kept at a certain distance, and the metal pipes must be grounded to form a Faraday cage-like effect to further enhance the shielding ability.
Choosing the right cable is also a key link in avoiding interference. The anti-interference performance of the monitoring tv wiring harness directly affects its ability to resist strong electrical interference. When selecting, cables with good shielding performance should be given priority. For example, double-layer shielded cables use aluminum foil and tinned copper braided mesh structure, which can effectively block the intrusion of external electromagnetic interference. For video signal transmission, coaxial cable can be selected, and its characteristic impedance matching can reduce signal reflection; for data signal transmission, Category 5e or Category 6 shielded twisted pair is a better choice, and differential transmission can offset common mode interference. In addition, the insulation material of the cable is also very important. Insulation materials with low dielectric constants can reduce capacitive coupling and reduce the interference of strong power lines to monitoring tv wiring harness through distributed capacitance.
Optimizing the grounding system is crucial to eliminate interference. Improper grounding can easily lead to a potential difference between the strong power system and the monitoring system, forming a ground loop current, which in turn causes interference. In the grounding design, the single-point grounding principle should be followed, and the signal ground of the monitoring system and the protection ground of the strong power system should be connected at a single point at the main grounding terminal box to avoid multi-point grounding to form a loop. If the strong power system adopts the TN-S system, the monitoring system can achieve floating ground connection through an isolation transformer or a signal isolator to cut off the ground loop. At the same time, the grounding resistance should be strictly controlled. Good grounding can effectively reduce the ground potential rise and reduce the generation of interference.
During the construction process, attention should be paid to avoid interference caused by human factors. Construction personnel should strictly follow the specifications to ensure that the cable connection is firm and the contact is good. During the threading process, the cable sheath should be avoided from damage to prevent the shielding layer from failing. At the same time, the construction site should be kept clean, the cables should be avoided from being tangled, and the strong power lines and monitoring TV wiring harness should be prevented from accidentally contacting. In addition, after the construction is completed, a comprehensive test should be carried out, and the transmission quality of the signal should be detected by professional instruments to promptly discover and solve potential interference problems.
For situations where interference has already occurred, corresponding remedial measures need to be taken. A filter can be installed at the input end of the monitoring equipment to filter out high-frequency common-mode interference and noise of specific frequencies. For some monitoring systems with high requirements for picture quality, digital noise reduction algorithms can also be enabled at the software level to process the interference in the picture. However, software noise reduction may have a certain impact on the picture quality, which needs to be weighed according to the actual situation.
Finally, regular maintenance and inspection are also important measures to ensure the normal operation of the monitoring system. As time goes by, the cables may age, break, and the grounding system may also be affected by environmental factors. Therefore, it is necessary to regularly check the wiring system, replace damaged cables in time, and repair grounding system faults. Through continuous maintenance and management, it is ensured that the strong power line and the monitoring TV wiring harness will not interfere with each other when laid in parallel, and the stable operation of the monitoring system is guaranteed.
