I. Introduction to Computer and Data Center Power Distribution

　　Once computer and network communication equipment is put into service, failure to establish a long-term, stable power supply system to ensure the normal operation of such equipment and its associated peripherals will inevitably lead to serious political and economic consequences.

　　Typically, the power supply system consists of a single power feed supplemented by a generator set.

　　It is impossible to guarantee reliable power supply without proper measures. A high-quality, efficient power distribution environment plays a crucial role in the data center. Therefore, power distribution in the data center is its “heart” and a key focus of the overall data center project.

　　II. Design Basis and Overview of the Power Supply and Distribution System

　　The power supply and distribution system for computer equipment is the prerequisite and guarantee for the normal operation of computer systems. According to GB 50174 and GB 2887, computer power supply methods can be classified into three categories:

　　Class I power supply: An uninterruptible power supply system must be established.

　　Category II power supply: A power supply system with redundancy must be established.

　　Three categories of power supply: considered based on general user power supply.

Distribution System

　　III. Power Distribution Requirements for the Computer Room

　　(1) The data center distribution cabinets shall be designed to provide accurate and reliable power supply to each circuit based on its intended use. This design proposes the use of two distribution cabinets—the mains power distribution cabinet and the UPS distribution cabinet—such that power-supply loads of different natures are not controlled within the same cabinet. A modular architecture is adopted to implement all distribution functions, and spare circuits shall be provided in the distribution cabinets to accommodate future expansion of data-center equipment.

　　(2) The automatic air switches, contactors, fuses, disconnect switches, and other components selected for the distribution cabinet shall be reliable in performance, meet the design requirements in terms of technical specifications, and be capable of satisfying the operational requirements of computer equipment and its auxiliary devices.

　　(3) The distribution cabinet shall be equipped with an emergency switch. In the event of a serious accident or an unexpected fire in the entire computer room, the switch shall be able to immediately disconnect the power supplies to the computers, the air-conditioning system, and the fresh-air ventilation system.

　　(4) Each branch circuit in the distribution cabinet shall be equipped with an indicator light to show the on/off status of the respective circuit.

　　(5) Within the distribution cabinet, connection devices for the neutral conductor and the protective earth conductor shall be provided in accordance with the specific requirements of the computer equipment and its auxiliary devices. The neutral conductor, the protective earth conductor, and the enclosure of the distribution cabinet shall be electrically insulated from one another.

　　(6) The busbars, grounding bars, and all cables, conductors, neutral conductors, and grounding conductors used inside the distribution cabinet must comply with national standards and be marked and numbered in accordance with the color codes prescribed by the state.

　　(7) Minicomputers, network equipment, and PC servers shall be supplied with power from separate, independent distribution circuits within the distribution cabinet.

　　IV. Principles of Data Center Power Distribution Design

　　(1) A dedicated, independent power supply provides power exclusively to computers and network communication equipment;

　　(2) A surge arrester must be installed on the distribution cabinet to protect against lightning strikes and the effects of switching operations in the power grid.

　　(3) After the installation of the data center equipment system, three-phase balance must be considered;

　　(4) Give due consideration to power supply frequency, voltage fluctuations, and the load-carrying capacity of the utility grid;

　　(5) Power and lighting wires and cables shall, wherever possible, be routed along the ceiling using cable trays and galvanized steel conduits. UPS cables shall be shielded to minimize electromagnetic interference and routed beneath the floor; interference-suppression measures must still be implemented during installation.

　　(6) This system shall establish reliable electrical connections between the protective earth conductor and the metal enclosures of all equipment, cable trays, conduit for wiring protection, metal aluminum-plastic panels, and metal supports, and shall route these connections to the original system grounding electrode, ensuring reliable grounding that complies with code requirements.

　　(7) Installation height of wall-mounted outlets: 300 mm above the finished floor level. Installation height of switches: 1400 mm above the finished floor level;

　　(8) DC grounding in the equipment room shall be separate from AC protective grounding: the DC grounding grid shall be connected to the building’s DC grounding electrode at an appropriate location, and such connection shall comply with electrical requirements;

　　(9) Lighting, air-conditioning, and maintenance wiring and cables shall be flame-retardant (ZR) double-insulated wires and cables. UPS cables shall be RVVP-grade cables. Interference-suppression measures shall be implemented during installation.

　　(10) Lighting shall use glare-free, reflective grille-type luminaires;

　　(11) Design illumination levels: ≥400 lux in the main computer room; ≥200 lux in the auxiliary computer room; ≥50 lux for emergency lighting.

　　(12) Prevent sudden power outages and surges in the power grid;

　　(13) The power supply’s stability deviation shall not exceed ±5% of the rated value;

　　(14) The power supply voltage shall have low ripple and minimal interference, and external electromagnetic interference must be prevented from entering the system.

　　(15) The power supply system should not be connected in parallel with high-capacity inductive loads to avoid the occurrence of high-voltage inrush currents.

　　(16) Prevent frequency drift in the power grid;

　　(17) Maintain a low-impedance grounding system;

　　(18) Computer and network communication equipment systems have stringent power-quality requirements, typically demanding that the power supply meet the following specifications: voltage tolerance of ±5%, frequency tolerance of ±1%, and harmonic distortion below 5%. To ensure the stable operation of such equipment, UPS power supplies are generally employed. If the grid exhibits significant voltage fluctuations, an isolation transformer or a compensating voltage regulator should be installed between the utility power supply and the UPS.

Distribution Scheme

　　V. Selection of Other Materials for Data Center Power Distribution

　　The insulation levels of power distribution cables and conductors for electrical equipment in the computer room shall comply with the relevant provisions of GB 50217—94, “Code for Design of Power Cables.” All power supply cables for equipment in the computer room shall be high-quality copper-core cables. The two types of outlets are differentiated by frame color: standard mains power outlets use conventional off-white panels, while UPS outlets use colored panels. All wiring materials and switches shall be from well-known brands.

　　(1) Low-voltage distribution circuits within the equipment room shall use flame-retardant copper-core shielded conductors or copper-core shielded cables, with insulation performance complying with the relevant requirements of GB 50217-94 “Code for Design of Power Cables.” The number of copper cores in the cables shall be selected to meet the power requirements of the electrical equipment in the equipment room.

　　(2) In addition to meeting the required current-carrying capacity, electrical wires and cables in the equipment room must also comply with flame-retardant requirements.

　　VI. Essential Equipment for Data Center Power Distribution

　　(1) Lighting System

　　Lighting shall be provided by luminaires coordinated with the suspended ceiling, specifically grille-type luminaires that deliver high illuminance without glare. The light sources shall be low-color-temperature, daylight-type fluorescent tubes. The illumination level in the equipment room shall be no less than 500 lx; emergency lighting shall utilize grille-mounted luminaire panels with an illuminance requirement of no less than 50 lx. These grille luminaires must be equipped with high-quality electronic ballasts that ensure energy efficiency, excellent start-up performance, a high power factor, zero audible noise and flicker, and no interference with computer power supplies. Luminaires shall be installed in a manner that is both functional and aesthetically pleasing to minimize glare. Automatic control with interlock to the mains supply shall be employed. Emergency lighting shall be powered by both the mains and the UPS; in the event of a mains failure, the system shall automatically switch over to the UPS within the equipment room. Evacuation signage lights shall be installed at the main entrance, with an illuminance of no less than 0.5 lx.

　　(2) UPS Uninterruptible Power Supply System

　　UPS employs IGBT power devices and multiple protection technologies, while advanced distributed direct parallel connection technology ensures online capacity expansion and system redundancy.

　　The output employs an isolation transformer to effectively suppress third-harmonic distortion and exhibits strong overload and surge-impulse resistance.

　　Regular automatic battery self-tests, backup time prediction, and intelligent battery management;

　　Supports multiple backend communication protocols, including RS-232, RS-485, SNMP, and MODEM.

　　Considering future capacity expansion, the UPS systems selected will be capable of parallel operation regardless of any subsequent changes in individual UPS power ratings.

　　(3) Auxiliary Power Supply and Distribution System

　　To prevent potential interference to the computer system caused by auxiliary electrical equipment operating within the data center, such equipment is typically supplied with power from a dedicated subsystem known as the auxiliary power distribution system. This system provides power to other equipment that supports the operation of the computer system, including air-conditioning units, maintenance equipment, fresh-air ventilation systems, lighting fixtures, test equipment, automatic fire-suppression systems, and auxiliary power outlets, among others.

　　VII. Advantages of Data Center Power Distribution

　　First, traditional distribution cabinets use analog pointer meters or digital display meters, which can only provide limited monitoring of cabinet parameters and meet basic requirements. In contrast, precision distribution cabinets employ highly integrated, high-reliability computer motherboards to comprehensively monitor all operational parameters of the system and present this information in an integrated HMI display, thereby reducing the space occupied by the cabinet and increasing its utilization rate.

　　Second, traditional distribution cabinets are solely responsible for power distribution, routing electrical supply to load cabinets; in contrast, precision distribution cabinets not only provide power distribution management but also offer operational and safety management capabilities, thereby significantly enhancing the reliability of the entire power distribution system and reducing risks.

　　Third, traditional distribution cabinets support fewer circuits and occupy a larger footprint; in contrast, precision distribution cabinets employ high-precision, highly integrated modules that maximize cabinet volume, accommodate more circuits, and thereby reduce the required floor space.