There are two types of electrical cabinets, one is the power distribution cabinet and the other is the control cabinet.
From a structural point of view, the electrical cabinet is composed of a shell, a steel structure and various installation boards, as well as components, instrumentation equipment, measurement and control devices and cables.
There are partitions inside the electrical cabinet. Partitions include busbar compartment, component compartment, outlet compartment, etc. The compartment exists to avoid the effects of electrical shock and heating.
We refer to the power transmission and control loop as the primary loop, and implement measurement and control, data collection and amplification, indicating that the information exchange loop is called the secondary loop. Therefore, the components in the electrical cabinet are also divided into primary circuit components and secondary circuit components. In addition, the primary loop is also called the primary loop, and the secondary loop is also called the control loop.
For primary circuit elements, when a short circuit occurs, only circuit breakers and fuses can disconnect the short-circuit current, so circuit breakers and fuses are called active elements, and other electrical appliances, including bus bars, are called passive elements.
Since the short-circuit current will cause electrical shock and thermal shock to the electrical cabinet, we divide the electrical cabinet's ability to withstand electrical shock into dynamic stability and thermal stability. Dynamic thermal stability is the key technology of electrical cabinets.
For electrical cabinets, the main circuit components are rated for overload protection and short-circuit protection, known as overcurrent protection. Overcurrent protection is closely related to the design of distribution systems and distribution networks, the grounding protection of distribution, loads and loads, and the wires and cables connected to the distribution system.
The operation of power distribution equipment generates temperature. We subtract the ambient temperature from the temperature of the power distribution equipment, which is called heating up. The temperature rise has a specified value. After exceeding the specified value, the components in the electrical cabinet will be damaged, the insulation will be damaged, and when the body touches the surface of the electrical cabinet, it may cause injury. Therefore, heating is an important performance indicator of electrical cabinets.
When a short circuit occurs, an arc will be generated when the switchgear breaks the short-circuit current, and the burning of the arc will cause damage. The busbar system in the switch cabinet will generate huge power due to the flow of short-circuit current, and its value can reach several tons to more than ten tons of power. Such a huge amount of power will have a significant impact on the structure of the electrical cabinet, serious or even disintegration.
The way components in an electrical cabinet are controlled is usually system-dependent. For example, the switching mode of power supply and distribution, the control method of the motor, and the start-stop control of the self-provided generator, as well as the collection and control of distributed electrical parameters, that is, DCS, etc. The control of many electrical cabinets chooses PLC to operate.
Many times, PLC can not only perform operation tasks, but also perform data management, data transmission and man-machine confrontation control, support man-machine interface, power monitoring system and DCS system, these data can also be sent to intelligent building management system, fire protection system management system, etc.
Post time: Aug-11-2022