The column head cabinet is a cabinet used to allocate and manage one or more columns of cabinets in the same computer room, and has protection functions. In power room, communication equipment room, and large network room, column head cabinet is necessary and also necessary.

1. Basic concept of column head cabinet

A column head cabinet is a cabinet located at the top (first position, equivalent to a head) of a row of cabinet equipment, usually called a column head cabinet. It is generally composed of a cabinet body and accessory components, among which the cabinet body is composed of a skeleton, front and rear doors (single side cabinets do not have a back door, but should have a back plate), side panels, top plates, bottom plates, etc. The column head cabinet is a cabinet with protective functions.

The column head cabinet can be divided into column head cabinet, column middle cabinet, and column tail cabinet according to the installation position. The column head cabinet is divided into strong current column head cabinet and weak current column head cabinet.

The specific environmental conditions and appearance requirements for the column head cabinet are as follows:

1) Environmental conditions

Working temperature: -5~+40 °C

Relative humidity: ≤ 85% RH (at 25 ± 5 ℃).

Altitude: ≤ 1000m. When the altitude is greater than 1000m, it should be derated according to the general requirements for semiconductor converters and the regulations for grid commutation converters.

Vertical inclination: ≤ 2 °.

2) Appearance requirements

The coating layer of the cabinet should have a smooth surface, uniform color, no sagging, and no exposed bottom; The metal parts are free of burrs and rust.

The cabinet door panels and side panels are flat, without distortion, deformation, or obvious shaking; The opening of the door panel is uniform.
The cabinet markings should be complete, clear, uniform in color, durable and reliable. Labels or positions should be set up above the front and back of the cabinet to indicate the serial number, and positions should be set up on the side panels of the cabinet facing outward at the head and tail of the column to indicate the serial number.
Cabinets and their accessories, coatings, markings, decorations, etc. should all be made of flame retardant or non combustible materials.

2. Weak current column cabinet

The weak current column head cabinet can be divided into network column head cabinet, KVM column head cabinet, server column head cabinet, etc.

A fully enclosed or semi enclosed cabinet, also known as a server cabinet or cabinet, used to place computer equipment, data network equipment, or related equipment and provide environmental conditions such as information network, power supply, and cooling required for equipment operation. Usually, a 19 inch standard cabinet is used, which is a specification series

with a cabinet width of 600mm, a device panel width of 19 inches (482.6mm), and a height of an integer multiple of 1U (44.45mm). In rare cases, 23 inch standard cabinets are also used. In special cases, cabinets can be customized according to the size of user needs. The appearance of the cabinet is shown in the following figure.
1)

(1) Network header cabinet

1) Characteristics of network header cabinet

Taking a reasonable structure and popular demand as the leading design concept;

Have good ventilation performance, with ventilation holes facing the front door and
ventilation holes facing the back door;

Designed primarily for communication and data;
All are made of high-quality cold-rolled steel plates with precision craftsmanship, and the
stress distribution is uniform;
Complete machine electrostatic powder spraying;
The welded frame structure has better load-bearing performance;
□ Removable fully open structure, convenient for transportation, installation, and
maintenance, beautiful and smooth in shape, and convenient for disassembly and assembly.

2) Product composition of network header cabinet

The main frame structure of the network header cabinet is made of high-quality cold-rolled steel plate welded together, with a generous appearance and can be wired up and down. The top is equipped with a heat dissipation fan, which is conducive to active equipment heat dissipation. There are different capacities such as 6U, 9U, 12U, 16U, 18U, 20U, etc.
Network cabinets are generally composed of a cabinet body and auxiliary components, including a skeleton, installation columns, front and rear doors, side panels, top plates, bottom plates, and layer plates. Auxiliary components include power distribution units, network interfaces, wiring ducts, door locks, flow hoods, sealing components, fans, etc.

3) Product classification of network header cabinets

According to the different cooling methods of air conditioning in the computer room, the network header cabinet can be divided into forward air, lower air, and upper air network header cabinets.
According to the presence or absence of network cabinet doors and the degree of sealing,network cabinets can be divided into closed, semi closed, and open cabinets.
According to the type of power supply used, the network header cabinet can be divided into AC 220V network header cabinet, AC 380V network header cabinet, DC 48V network header cabinet, and DC 240V network header cabinet.
According to the different positions of communication cables and power cables entering the cabinet, the network header cabinet can be divided into upper routing, lower routing, and upper and lower routing header cabinets.

4) Size, structure, and configuration of network header cabinets
① Outline dimensions of network header cabinet

The cabinet height is generally divided into four types: 2000mm, 2200mm, 2400mm, and 2600mm. It is recommended to choose 2200mm, and the height of the lower air inlet cabinet should not exceed 2200mm.
The recommended cabinet width is 19 inches (600mm), and in special cases, 23 inches (800mm) can be used.
The depth of the cabinet is generally divided into five types: 800mm, 900mm, 1000mm, 1100mm, and 1200mm. The depth of the lower inlet cabinet should not be less than 1100mm, and it is recommended to use 1100mm; The depth of the forward air cabinet should not exceed 1100mm, and it is recommended to use 1000mm.

② Basic structure of network header cabinet

The basic structure of the network header cabinet consists of a frame, front and rear doors, side panels, top plates, bottom plates, and corresponding positioning and fasteners. The interior of the cabinet can be equipped with installation columns, laminates, air intake and exhaust, power supply and distribution devices, etc. The basic structure of the lower air inlet cabinet is shown in the figure. The basic structure of the front air inlet cabinet and the upper air inlet cabinet are similar to the lower air inlet cabinet, and can also refer to the following figure.

The structure of the network header cabinet should be firm, with the bottom and top fixed up and down, and should be able to withstand the load of the top cables and structural components;
Each component and internal and external overall structure has sufficient rigidity and toughness to prevent shaking and structural deformation after equipment installation. The cabinet structure and its internal installation columns, laminates, and other components should meet seismic requirements.
The frame of the network cabinet is processed with cold-rolled steel plates or aluminum alloy profiles, and the side panels, front and rear doors, laminates, and reinforced top and bottom structures are made of cold-rolled steel plates or materials with better performance.
The assembly of the network header cabinet should have consistency and interchangeability, and the components should use standard and universal parts to the maximum extent possible, with no loose fasteners. The exposed and operating parts should be smooth and free from sharp edges and burrs.
The door and side panel of the network cabinet are detachable structures, with flexible opening and closing rotation, reliable locking, and convenient construction, installation, and maintenance.
The opening angle of the network header cabinet door should not be less than 110 °; The disassembly and assembly of side panels should not affect the overall width of the cabinet.
The front and rear doors of the network cabinet should adopt an external door opening method, with the front door being a single door and the back door being a single door or symmetrical double door; The front and rear doors are equipped with locks, and can also be replaced with independent locks according to user needs.
The network header cabinets can be installed in parallel and should be equipped with parallel connectors.

③ Internal structure of network header cabinet

4 or 6 installation columns should be installed inside the network header cabinet for equipment installation and fixed layer boards. The installation of the column allows for forward and backward movement and adjustment. The spacing, hole spacing, and other internal dimensions and structures of the cabinet for installing columns should meet the user's requirements.
The depth of the internal layer of the network header cabinet is 600mm ± 5mm, with standard
layer plates bearing N40kg and reinforced layer plates bearing N80kg. The layer board should be easy to install and disassemble, and its installation height and front and rear positions can be adjusted. The fixation method of the laminated board can be determined by user needs, using screws, elastic pins, clamping components, and other fixation methods.
The effective installation depth of internal equipment in the network header cabinet is N720mm.

④ Network header cabinet accessory configuration

Set up a side cable tie board or routing slot on the left and right sides of the rear of the network header cabinet, respectively, for the layout and binding of communication cables and power cables; All cable management components should be set reasonably, adequately, and conveniently.

(2) KVM column head cabinet

The KVM column head cabinet category is similar to the network column head cabinet in terms of characteristics, product composition, product classification, technical requirements, size, structure, and configuration. KVM equipment is installed.

(3) Server column header cabinet

The server header cabinet category is similar to the network header cabinet in terms of characteristics, product composition, product classification, technical requirements, size, structure, and configuration. KVM servers are installed.
3. Strong current column head cabinet
Strong current column cabinets can be divided into ordinary power column cabinets, AC/DC column cabinets, precision distribution column cabinets, etc.

(1) Basic Concept of High Voltage Train Head Cabinet
1) Product composition of power column cabinet

The power supply cabinet is generally composed of a cabinet body and auxiliary components.
The cabinet body is composed of a skeleton, front and rear doors (single side cabinets do not have a back door, but should have a back plate), side panels, top plates, bottom plates, etc. The auxiliary components include input and distribution modules, shunt output modules, neutral wire bars, ground wire bars, signal output interfaces, electricity metering modules, data display devices, door locks, and machine piers.

2) Product classification of power column cabinet

The power supply column head cabinet can be divided into column head cabinet, column middle cabinet, and column tail cabinet according to the installation position.
The power supply cabinet can be divided into single side cabinet and double side cabinet according to the direction and quantity of the operating surface and cabinet door. When the power supply column cabinet is used as a column head cabinet or a column tail cabinet, it is advisable to choose a single side column cabinet.
The power supply cabinet can be divided into single circuit cabinet and double circuit cabinet based on the number of independent power supply circuits input and distributed.

3) Working principle of power column cabinet

After the 380V (or 220V) AC input power enters the cabinet, the live wire is connected to the main circuit breaker through the "peephole copper terminal", and then passes through the main circuit breaker - current transformer - busbar - several branch circuit breakers - corresponding terminal blocks on the outgoing module - user load; After the working ground wire enters the
cabinet, it is connected to the main circuit breaker through the "peephole copper terminal", and then passes through the working ground copper bar on the main circuit breaker outlet module.
Then, it passes through the working ground copper bar and the corresponding wiring terminals on the outlet module user load to complete the distribution function of AC power. At the entrance of several wiring terminals on the outgoing module, collect the on/off signals of corresponding branch circuit breakers, send them to the centralized sampling box, and then to
the electrical control board to achieve the on/off alarm and indication functions of each branch.

4) Main characteristics of power supply cabinet

The cabinet body of the power supply column head cabinet is made of high-quality cold-rolled steel plate, with electrostatic spraying on the surface, which is beautiful and elegant.
The power distribution of the power column cabinet adopts a modular and standardized design, with flexible configuration and convenient production.
The internal wiring of the power supply cabinet is convenient, reliable, and aesthetically pleasing.
The power supply cabinet has the advantages of convenient customer management of incoming and outgoing lines and full frontal operation.
Special design can achieve live capacity expansion.
Equipped with AC input short circuit protection function.
Equipped with lightning protection device.
Sound and light alarm function: shunt alarm, overvoltage alarm, undervoltage alarm, lightning
protection alarm.
Display function: LCD display, branch dual color indicator light display, alarm light display, and work indicator light display.
Each branch is equipped with corresponding branch identification numbers, indicator lights, and convenient identification plates for customers.
Storage of information: When the equipment experiences a power outage fault, all settings and status parameters of the power cabinet before the fault can be automatically saved. After the device is powered back on, the settings and status parameters of the power cabinet are automatically restored.
Equipped with RS232 interface to achieve centralized monitoring of the power cabinet.

5) Environmental conditions requirements for power supply cabinet
① General requirements for power column cabinet

The power column cabinet is equipped with a complete set of detachable and replaceable fixed power distribution units (PDUs) for the introduction, distribution, protection, opening and closing, and plugging (sockets or terminals) of the cabinet equipment power supply. Within the same cabinet, AC power distribution and DC power distribution should not be mixed (except for cabinet cooling fan power distribution).

② Structure and installation requirements of power column cabinet

It is recommended to use a vertical strip integrated structure for the power distribution unit of the power column cabinet, which integrates power distribution, protection, and wiring together.
The front of the unit can be disassembled for easy installation, replacement of the wiring module and wiring;
The power column cabinet adopts a split structure that separates the introduction, distribution, and protection parts of the power supply from the plug-in part. The introduction, distribution, and protection parts of the power supply are placed in the distribution unit at the top or bottom of the equipment, while the plug-in part is still a vertical strip unit structure.

③ Environmental conditions of power supply cabinet

Working temperature: -5~+40 ℃.
Relative humidity: ≤ 85% RH (at 25 ± 5 ℃).
□ Altitude: ≤ 1000mo When the altitude is>1000m, it should be derated according to the general requirements for semiconductor converters and the regulations for grid commutation converters.
Vertical inclination: ≤ 25%.
Atmospheric pressure: 70-106kPa.

④ Basic requirements for power column cabinet

The power supply cabinet should comply with the relevant technical requirements of YD/T585, and the requirements should refer to the relevant clauses in YD/T585.
The materials and components (fasteners, seals) used in the power supply cabinet should comply with Chinese national standards, communication industry standards, and relevant IEC standards for their mechanical, chemical, electrical, and other performance testing methods.
The creepage distance and electrical clearance between each live circuit in the power supply cabinet and between live or grounded components should comply with the provisions of GB/T3797-2005.
When the rated current is applied to the power supply cabinet, the temperature rise of each electrical component and component should comply with the relevant requirements of YD/T585.
The power supply cabinet should have anti lightning and anti surge protection devices, and the lightning protection level should meet the requirements of YD/T944 for the second level of lightning protection classification.

⑤ Appearance structure of power column cabinet

The overall dimensions of the power supply cabinet should be coordinated and unified with the network cabinet, mainly determined by the overall dimensions and output capacity of the network cabinet.
The structural design of the power supply cabinet should ensure safe and reliable operation, convenient maintenance and inspection. The heat, arc, impact, vibration, magnetic field or electric field generated during the operation of each electrical component should not affect the normal operation of other electrical components.
The power supply cabinet should adopt a fully enclosed structure, with side panels, bottom panels, top panels, and front and rear doors (single side cabinets do not have a back door, but should have a back panel).
The appearance of the structural components of the power supply cabinet should be flat, and all welding joints should be uniform, firm, without cracks, residue, obvious deformation or burning through defects.
The cable entry and exit method of the power column cabinet requires upper entry and upper exit (or upper entry and lower exit), and the top should have an entry hole with at least one 80mmx500mm rectangular entry.

The power supply cabinet should adopt a double door structure with upper and lower doors
(single or double doors can be selected within the width of 850mm; when the width of the
cabinet is above 850mm, both upper and lower doors should be designed with double doors),
and the doors should be flexible to open, with each door opening angle not less than 90 °.
The surface of the power supply cabinet should be coated with a non glare reflective coating,
with a smooth and uniform surface, no sagging or exposed bottom, and no burrs or rust on the
metal parts.
The wiring of the power supply cabinet should be reasonable, and the connection of each wire end should be reasonable, with obvious danger signs.
The power supply cabinet and its auxiliary components, coating layers, signs, decorations, etc. should be made of flame retardant or non combustible materials.

⑥ Power distribution requirements for power column cabinet

The power supply cabinet should meet the requirement of providing completely independent dual circuit power supply to one or more network cabinets.
For dual circuit cabinets, each circuit should have a separate neutral bar and should not be interconnected or shared.
The setting of the number of output branches for the power column cabinet should meet the requirements for the number and capacity of the network cabinets it is assigned to.
Rated value:
Rated voltage: AC three-phase five wire system 380V
Rated frequency: 50Hz
Single input (total) rated current (A): (50), 63, 80, 100, 160, (225), (250)
□ Output shunt rated current (A): (10), 16, 20, 25, (32)
Note: The values in parentheses indicate that they are generally not recommended, and can also be used in special circumstances.

6) Electrical performance of power column cabinet

Insulation resistance: In distribution equipment, the insulation resistance between the conductors of each live circuit and between any conductor and the casing (or ground) is ≥ 30M Ω.
Electrical strength: AC2500V, 50Hz, Imin, no breakdown, no flashover.
Rated voltage of AC power distribution equipment: 380V or 220V.
7) Structure of power column cabinet
Electrical components on the front of the power column cabinet. There are four types of alarm indicator lights (branch, overvoltage, undervoltage, and lightning protection), LCD LCD display module, and membrane button switch installed on the upper panel of the front of the cabinet.
The buzzer and power indicator light are installed on the front of the cabinet top frame.
Composition of the power supply cabinet monitoring system. The power supply cabinet monitoring system consists of a sampling panel, rectifier board, control board, LCD display module, membrane switch, LCD indicator light board, power supply working indicator light board, alarm sampling line, and buzzer.
Power input line of the power column cabinet. The power supply line generally adopts a dual power supply line. When one power supply system fails and loses power, the other power supply automatically switches on to ensure power supply continuity. To achieve 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. It also has isolation function for easy maintenance.
The intelligent monitoring system of the power supply cabinet can monitor, alarm, and count the switch status and load situation of the distribution system. The input electrical parameters that can be monitored include: electricity quantity, active power, reactive power, apparent power, power factor, three-phase voltage, current, frequency, etc. The output branch electrical parameters that can be monitored include: rated current, actual current, load percentage, load current harmonic percentage, load electricity quantity, etc Power factor, etc. These monitoring information can enable users to grasp the operation status of various devices, adjust load distribution in a timely manner, have a clear understanding of the power consumption of each cabinet, and provide reliable basis for energy efficiency management and energy consumption
reduction.

(2) Ordinary power supply cabinet

The ordinary power supply cabinet is mainly used in the communication room and station transmission equipment room, installed at the head or tail of the equipment, for power distribution of communication and network equipment.
Characteristics of ordinary column cabinet:
1) The interior of the cabinet adopts a modular design, which is neat and beautiful. The ordinary column cabinet adopts a glass door design, which is intuitive and reliable. Both the top and bottom of the cabinet are equipped with cable holes for cable entry from the machine room wiring duct or from the cable trench.
2) The use of highly reliable circuit breakers eliminates the disadvantage of fuse protection, greatly shortens fault handling time, and ensures safe and reliable equipment use.
3) The column head cabinet is equipped with overload and short circuit protection functions for each branch, ensuring stable and reliable performance.
4) The standard power distribution cabinet can provide up to 96 branches and uses terminal
outputs.
5) Equipped with unified zero and ground bars, it can effectively ensure grounding.