Detailed introduction of Integrated Wiring System electrical protection

This article introduces the electrical protection knowledge of the Integrated Wiring System. Many people may not understand the electrical protection yet. It does not matter. After reading this article, you will certainly have a rough understanding of the Integrated Wiring System electrical protection, I hope this article will teach you more things.

The Integrated Wiring System is part of smart buildings. Compared with traditional cabling systems, it features compatibility, openness, flexibility, reliability, advancement, and economics, it connects voice, data, Image devices, and exchange devices to other information management systems, as well as external communication networks. It can be said that the Integrated Wiring System is like an expressway of a smart building. With this information expressway, it is very easy to think about any application system. The purpose of Integrated Wiring electrical protection is to reduce the damage to the cables and related connection hardware of the Integrated Wiring System due to electrical faults, and to avoid damage to terminal equipment or devices, ensure the normal operation of the system.

I. Electrical Protection

When an outdoor cable enters a building, it is usually transferred to the room at the entrance. Electrical protection equipment should be installed at the transfer place, in this way, the user's equipment is damaged by the induction potential generated by lightning strikes on the cable or the contact with the power line.

Electrical protection can be divided into overvoltage protection and overcurrent protection. These protection devices are usually installed in a dedicated room or wall at the entrance of a building.

The overvoltage protection of Integrated Wiring can be either gas discharge tube protector or solid-state protector. The gas discharge tube Protector uses the gap of disconnections or discharge to limit the voltage between the conductor and the ground. The discharge gap is formed by two metal poles sealed in the Ceramic Housing and filled with inert gas. When the potential difference between the two electrodes exceeds V of AC or the lightning surge voltage exceeds V, an arc occurs in a gas discharge tube, providing a conductive path between the conductor and the ground electrode.

Solid State protector is suitable for low breakdown voltage of 60 ~ 90 V), and the circuit cannot contain the ring voltage. It uses electronic circuits to drain excessive harmful voltage to the ground without affecting the transmission quality of the cable. The solid-state protector is an electronic switch. It can perform a stable voltage reset before it reaches the breakdown voltage. Once it exceeds the breakdown voltage, it will introduce the overvoltage to the ground, solid State protectors provide optimal protection for cabling systems.

In addition to Overvoltage Protection, the Integrated Wiring System also adopts overcurrent protection. The over-current protector is connected in series. When the over-current occurs, the line is cut off. For ease of maintenance, overcurrent protection generally uses a Protector with the automatic recovery function.

Ii. Shielding

Electromagnetic interference and radiation are problems of the entire application system. The interference caused by cables in the Integrated Wiring System is only part of the problem. The radiation energy is related to the voltage and frequency of the sent signal. Shielding is used to ensure the transmission performance of the Integrated Wiring channel in an interference environment. It consists of two parts: reducing the energy of the cable itself radiating outward and improving the cable's ability to resist external electromagnetic interference.

The overall performance of Integrated Wiring depends on the performance of the weakest cable and related connection hardware in the application system and the connection process. In the Integrated Wiring System, the weakest link is the distribution frame and cable connection components, and the contact parts of the information outlet and plug. When the shielding layer of the shielded cable cracks during installation, it also forms a weak link in the shielding channel. In order to eliminate electromagnetic interference, in addition to non-Intermittent points on the screen layer, the overall transmission channel must be shielded at 360 ° throughout the process. For a point-to-point connection channel, it is very difficult to achieve, because the information plug-in, jumper, and so on are difficult to achieve full shielding, coupled with the corrosion of the shielding layer, oxidation damage and other factors, therefore, no channel can truly block the whole process. At the same time, the shielding layer of the shielded cable has poor shielding effect on the low-frequency magnetic field and cannot resist the low-frequency interference caused by equipment such as motor. Therefore, shielding Cables cannot completely eliminate electromagnetic interference.

Theoretically, in order to reduce the external world, shielding measures can be used to shield static shielding and magnetic shielding. The shielding principle is that the interference current is short-circuited to the ground after the shielding layer is grounded. Therefore, it is very important to properly shield the ground. Otherwise, the interference will not be reduced, but will increase. When the grounding point is incorrectly arranged, the grounding resistance is too large, and the grounding potential is not balanced, it will cause grounding noise, that is, the potential difference is generated at a certain two points in the transmission channel, in this way, the interference current is generated on the metal shielding layer. At this time, the shielding layer itself forms the largest interference source, resulting in far inferior performance to the non-shielded transmission channel. Therefore, to ensure screen effect, the screen must be properly and reliably grounded.

In practical application, in order to minimize interference, in addition to ensuring the integrity of the Screen Layer and reliable grounding of the Screen Layer, you should also pay attention to the working environment of the transmission channel, stay away from various sources of interference, such as power lines, transformers, and electric data centers. When the Integrated Wiring environment is extremely harsh, the electromagnetic interference is strong, and the information transmission rate is high, optical cables can be directly used to meet the electromagnetic compatibility requirements.

Iii. System grounding

Cables of Integrated cabling systems and related connection hardware grounding are important means to improve application system reliability, reduce noise, and ensure security. Therefore, before wiring design and construction, the designers and construction personnel must carefully study the grounding requirements of all equipment, especially the application system equipment, determine the grounding requirements and the relationship between various ground wires. Improper handling of the grounding system will affect the stability of the system equipment, cause faults, and even burn down the system equipment, endangering the safety of the operator. The grounding of the Integrated Wiring System equipment room and equipment can be divided into DC work grounding, AC work grounding, safety protection grounding, lightning protection grounding, anti-static connection and shield grounding.

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