Accurately Grasp the Contemporary Concept of Building Electrical Systems

The development of building electrical technology advances in step with the development of building technology and electrical science and technology. In particular, with the development of information technology, building electrical technology has achieved leapfrog progress. Since the reform and opening up, extensive technical exchanges have been carried out internationally; many advanced new products and new technologies from around the world have continuously entered the Chinese building market, enabling the building electrical industry to take a new step forward. At the same time, with the emergence of modern buildings, the scope of building electrical design has expanded from the original single focus on power supply and distribution, lighting, lightning protection and grounding to new theories of applied mathematics and physics based on modern physics, electromagnetics, electronics, optics, acoustics and other theories, and is advancing toward comprehensive application in combination with electronic computer technology and information technology. This has not only automated the power supply and distribution systems of buildings, but also achieved optimal control and management of the water supply and drainage systems, air-conditioning and refrigeration systems, automatic fire protection systems, security monitoring systems, communications and closed-circuit television systems, and operation and management systems inside buildings. Today, building electrical systems have become an important part of the modern electrical science field and an important symbol of the development of modern electrical science. Therefore, to see the direction of industry development clearly, one must accurately grasp the contemporary concept of the industry and correctly understand its profound connotations.

In recent years, we have hoped to give "building electrical systems" a scientific and standardized definition and further explore its connotations. Through years of arduous practice and scientific exploration, domestic electrical design and construction installation practitioners have formed today's comprehensive engineering discipline. At present, the broad interpretation of "building electrical systems" is: building electrical systems are an applied discipline that uses buildings as a platform and electrical technology as a means to create a humanized living environment within limited space. Its narrow interpretation is: in buildings, modern advanced scientific theories and electrical technologies, including power technology, information technology and intelligent technology, are used to create an electrical system for a humanized living environment, collectively referred to as building electrical systems. The "electrical technology" involved here is mainly formed by integrating power technology, information technology and various types of building intelligence technologies.

It is worth mentioning that, in the power technology aspect of electrical technology, a power system refers to circuits and related lines intended to provide electrical energy and to transmit and use electrical energy. A power system is also commonly called a power supply system or a transmission and distribution system. Transmission and distribution lines and substations are the intermediate links connecting power plants and users and are part of the power system, known as the power network. In a power system, the lines that directly supply power to users are called distribution lines. The distribution network is composed of distribution lines and transformation and distribution lines of 10 kV and below. Its role is to distribute power to various types of users. The power system in "building electrical systems" usually refers to distribution networks of 10 kV and below, while power generation and high-voltage supply networks do not fall within the scope of "building electrical systems."

The Origin of Building Electrical Systems Is "Humanization"

Because building electrical systems are the power systems people come into closest contact with in buildings, and because building electrical systems directly serve people's lives, human needs are the very foundation of their existence; therefore, "humanization" is the most important feature of building electrical systems, involving the safety of electrical equipment use, sustainable development, and energy conservation and environmental protection.

Ensuring users' safety, reliability and high flexibility is the primary technical requirement for building electrical systems. In civil buildings, those operating electrical equipment are generally not professional electrical technicians, so protection against electric shock is particularly important. Electric shock refers to the pathological and physiological effects caused by current passing through the human or animal body, and is divided into two forms of injury: electrical injury and electric shock. Electrical injury refers to damage to the surface of the human body by current, which often does not endanger life safety; electric shock refers to damage directly caused to internal tissues by current passing through the interior of the human or animal body. It is a dangerous form of electric shock injury and often leads to serious consequences.

Electric shock to the human body can be divided into direct contact electric shock and indirect contact electric shock. Direct contact electric shock refers to electric shock suffered when the human body directly contacts the live parts of electrical equipment or electrical lines, characterized by the shock current formed by the contact voltage on the human body. The degree of harm caused by direct contact electric shock is the most serious. The shock current formed in the human body is far greater than the limit current that may cause ventricular fibrillation. Indirect contact electric shock refers to electric shock suffered when, due to insulation damage in electrical equipment or electrical lines causing a single-phase grounding fault, the exposed parts carry a fault voltage to ground and the human body contacts the exposed parts of the electrical equipment or electrical lines carrying this fault voltage. Indirect contact electric shock mainly causes casualties due to contact voltage or step voltage. Protection against direct contact electric shock refers to preventing contact with parts that are live under normal working conditions. Protection against direct contact electric shock can be divided into: complete direct contact protection; partial direct contact protection; and supplementary protection through fault current protection devices. Technical measures to prevent indirect contact electric shock usually include: reasonably selecting automatic power cut-off protection supplemented by equipotential bonding; preventing workers from simultaneously touching two different potential points; using double insulation or reinforced insulation; adopting local equipotential bonding; and adopting electrical isolation, etc.

Frequent and arbitrary operation is a prominent manifestation of humanization, but this places extremely high demands on electrical and appliance technology. Reasonably designing the various systems of building electrical systems and using advanced electrical equipment is extremely important for meeting building function requirements and saving capital construction investment. That is: according to the requirements of the electrical system, ensure improved continuity of power supply under various operating modes; make the electrical system as simple, clear and free of redundant electrical equipment as possible; make operation convenient when putting certain equipment or lines into or out of service; avoid misoperation; and make accident handling simple and rapid. Flexibility is also reflected in the possibility of adapting to development, especially as terminal electrical equipment must satisfy arbitrary operation.

In addition, due to the rapid development of various new technologies, especially the application of intelligent technology in building electrical systems; the rapid changes in household appliance technology, with the evolution of various new functions leaving people dazzled; and the development of networked communication technology as humanity enters the information age, it has become extremely important for the industry to have far-sighted sustainability, and only in this way can building functions adapt to the pace of the times.

Building electrical engineering is an important component of engineering project construction. As science and technology develop, the science and technology of building electrical systems are also becoming increasingly rich and diversified. The development of the times requires us to accurately grasp the significance of the building electrical industry.