The head cabinet is a cabinet on the top of a row of cabinet equipment. Usually the front end is called the head cabinet, and the end is called the tail cabinet. The main function is to provide power for the AC or direct load of this row of cabinets, and to perform functions such as power distribution, monitoring, measurement, protection, and alarming. The top cabinet is similar to a cabinet-type distribution box, and many circuit breakers are concentrated in it. Next, we will introduce the main functions and usage principles of the cabinets.
The power distribution column cabinet is referred to as the top cabinet for short, and the top cabinet is divided into ordinary top cabinet and precision top cabinet. Ordinary head cabinets are mainly used in communication equipment rooms and station transmission equipment equipment rooms. They are installed at the head and tail of the equipment, and are matched with bar-shaped communication equipment columns and optical terminal equipment columns. Through the power distribution device in this equipment, it serves as a Perform power distribution.
The precision column head cabinet is a vital part of the computer room power distribution in the entire computer room, but it is also a level that is easily overlooked. The current computer room equipment servers, air conditioners, UPS, fans, etc. have been able to monitor at any time This step, and the monitoring of power distribution in the computer room is just a blank. The traditional power distribution cabinet is just a few meters plus a few required switches. Second transformation (adding various modules). This is both cumbersome and ineffective. The power distribution circuit in the computer room is generally connected by two-way mains power. First, it enters the mains power distribution box, one part is for UPS, the other part is for air conditioners and lighting, and ordinary sockets. Connect to the PDU of each cabinet after the head cabinet and then to the load.
The power supply line of the head cabinet generally adopts dual power supply lines. When one power supply system fails and the power is cut off, the other power supply is automatically switched on to ensure the continuity of power supply. In order to realize short-circuit and overload protection, a molded case circuit breaker is used in front of the dual power supply to provide short-circuit and overload protection, and also has an isolation function for easy maintenance. The electrical fire monitoring system, electrical fire detector and monitoring unit are generally required to be installed in the box. Since the equipment in the computer room is very sensitive to lightning strikes, it is generally necessary to choose a surge protector.
Molded case circuit breakers can be selected for the main outgoing circuit of the top cabinet, and leakage modules can be installed if necessary. The power supply continuity of the equipment in the computer room is very important. The power parameter measuring instrument is equipped at the incoming line of the head cabinet, which can monitor the level of electrical parameters in real time, send fault alarm signals in time, detect potential hidden troubles in advance, and monitor the power consumption level at the same time.
The power distribution module can be selected as required in the top cabinet. The modular structure is convenient for disassembly and maintenance. The module allows users to quickly and flexibly add and delete circuits to meet the expansion needs of the power consumption of the computer room.
The power distribution cabinet is usually composed of automatic control switches, isolating switches, fuses, contactors, relays, ammeters, indicator lights, buttons, switches and other electromechanical components, semiconductor components and cabinets.
When designing a power distribution cabinet, it is first necessary to examine the relationship between computer electrical equipment, auxiliary electrical equipment in the computer room, and backup power supply equipment; secondly, to understand the load of various electrical equipment, the installation position of the control switch, and the ease of use , The layout of the power distribution cabinet is neat and unified; the control relationship between the various power distribution cabinets in the computer room must be improved.
1. General requirements for special power distribution cabinets in computer rooms
① When numbering the power distribution cabinet in the machine room, in addition to the normal number of the power distribution cabinet, the purpose of the power distribution cabinet should also be added. Such as: No. 5 UPS power input cabinet.
②The power distribution cabinet in the computer room should be designed according to the purpose, and the power supply should be accurate and reliable. Power supply objects of different nature should not be controlled in one cabinet. There should be a spare circuit in the power distribution cabinet for power consumption when expanding the equipment in the computer room.
③ The automatic control switches, contactors, fuses, isolating switches and other components selected in the power distribution cabinet must have reliable performance, technical indicators meet the design requirements, and meet the requirements of computer equipment and its auxiliary equipment.
④ There should be an emergency switch in the power distribution cabinet. When a serious accident or accidental fire occurs in the computer room, it should be possible to immediately cut off the power supply of the computer, air conditioner and Xinfeng.
⑤ The power distribution cabinet should be equipped with ammeters and voltmeters for checking the power supply voltage, current and the balance relationship between the three phases.
⑥The computer equipment control power distribution cabinet should be equipped with a frequency meter: for observing the frequency change of the UPS power output.
⑦ Each branch power supply in the power distribution cabinet should be equipped with indicator lights to indicate the on-off status of each power supply.
⑧In the power distribution cabinet, according to the different requirements of computer equipment and its auxiliary equipment, the connecting device for the neutral line and the grounding line should be set. The neutral wire is insulated from the ground wire and the enclosure of the distribution cabinet.
⑨The busbars, terminal blocks and various cables, wires, neutral wires, grounding wires, etc. used in the power distribution cabinet should meet the national standards. And according to the color mark and number stipulated by the state.
⑩ Various switches in the power distribution cabinet. Handles and operating buttons should be clearly marked to prevent misoperation during use. (11) When the aluminum row in the power distribution cabinet is connected with the copper parts, the aluminum-copper transition material should be used. If the aluminum-copper transition material is difficult, tin must be applied to the copper parts. (12) Some power distribution cabinets for special purposes can be equipped with alarm devices. (13) The insulation performance of the power distribution cabinet should meet the requirements of Article 20.1.1 of the national standard GBJ232-82 “Electrical Equipment Handover Test Standards”, generally not less than 0.5MΩ.