Computer room commonly used power supply uninterruptible power supply (UPS) power supply, due to the use of pulse width frequency modulation technology, the maturity of high-efficiency power devices, microprocessor development and other factors, the uninterruptible power supply has become the main means of power supply of the computer room. Uninterruptible power supply's biggest feature, lies in the uninterruptibility, and can maximize the provision of stable voltage, isolated from the interference of the external power grid. Once the external power grid blackout, UPS can be allowed in the equipment within a very short period of time (microseconds to milliseconds) automatically from the standby energy by the inverter transformed into voltage, frequency and phase are the same as the original power supply power supply to the computer continues to supply power. Or usually powered by the inverter, only in the event of inverter failure, by the static electronic switch automatically switch the computer instantaneous power supply to the external power grid or switch to another parallel with the UPS, to achieve uninterruptible power supply.UPS power supply has a high voltage and frequency stability, waveform distortion is also smaller, the interference is better than the external power grid, is the most ideal power supply of the computer system. Almost all of the important computer equipment using UPS power supply.

Due to the adoption of pulse width frequency modulation technology, the maturity of high-efficiency power devices, the development of microprocessors and other factors, uninterruptible power supplies have become the main means of power supply for computer rooms. The biggest feature of uninterruptible power supplies is their uninterruptibility, and they can provide stable voltage to the maximum extent and isolate interference from the external power grid. Once the external power grid fails, the UPS can automatically convert the backup energy through the inverter into electricity with the same voltage, frequency and phase as the original power supply to continue to power the computer in a very short time allowed by the equipment (microseconds to milliseconds). Or it is usually powered by an inverter, and only when the inverter fails, the static electronic switch automatically switches the computer to the external power grid or to another UPS connected in parallel to achieve uninterrupted power supply. The power supply provided by the UPS has higher voltage and frequency stability, less waveform distortion, and better interference than the external power grid. It is the most ideal power supply method for computer systems. Almost all important computer equipment is powered by UPS.

(I) Power supply layout and system design

Design and construction must fully understand and master the power supply object. Only by fully collecting the information of the equipment and system in the computer room can the power supply layout and system design be done well, so as to reasonably meet the power needs of the computer room.

According to the needs, we will set up a separate power management room for the computer room, and use a partition wall that meets the fire protection requirements to isolate it from the weak current equipment to prevent accidents such as noise from the power management room, battery acid and alkali leakage, and electrical fires from spreading to the computer equipment room. A single door opening toward the power management room is set between the computer equipment room and the power management room, and a glass observation window can also be considered. The power management room should have a cement floor, and a 0.3~0.5m high cement platform can be built to place the power distribution cabinet and UPS power supply for moisture and humidity prevention.

UPS main supply: host equipment, network equipment, security monitoring equipment, multimedia, fire protection, emergency lighting, etc.

Main power supply: air conditioning equipment, general lighting and ventilation, maintenance sockets, general power, etc.

(II）Power supply and distribution system

The power supply and distribution system fed by the main distribution cabinet adopts 50Hz AC, 380/220V three-phase five-wire power supply, TN-S grounding method, the neutral line and the ground line are set separately, and the voltage between the neutral line and the ground line is less than 1V. The power distribution cabinet and lighting distribution box adopt radial distribution to directly distribute to each power-consuming equipment.

All cables in the computer room must be designed with steel bridges, cable troughs or steel pipes for laying. Due to the large power supply current and wide load dynamic range of precision air conditioners, in order to prevent interference, it should be considered to choose another path to lay cables separately.

The power distribution cabinet (box) has a fire alarm linkage protection function. When a fire alarm occurs, it can be linked with the fire protection system to cut off the power supply in time, close the smoke and fire damper, and install a manual power cut-off device in the duty room. The switches and main components in the power cabinet and lighting box are imported products, and effective lightning protection measures are set. When conditions permit, it is best to use a dedicated power transformer for power supply in large computer rooms.

（III）UPS power supply and distribution system

The power supply range of the UPS power supply and distribution system is computer equipment (host and auxiliary equipment), communication equipment, network equipment, security monitoring equipment, fire protection system, emergency lighting, etc. The UPS output distribution circuit (each power distribution control switch is a circuit) needs to be set according to the equipment requirements in the computer room. Minicomputers/servers, network core switches and important routers should be powered by independent dual circuits. Other computer equipment can use a circuit with 3~4 sockets, fixed under the floor. It is reliable and convenient to send UPS power to the power distribution cabinet (terminal) of the main computer room. It should also be considered to install power distribution units (PDU) for key load equipment in the data center. These facilities are devices that combine the functions of several components into one device. They are usually small and more efficient than installing several independent panels and transformers separately. If the computer room is subdivided into different rooms or spaces, each of which is supported by their own independent emergency power switches (EPO), then these spaces should have their own independent horizontal distribution areas.

Power distribution units (PDU) integrate the functions of independent transformers, transient voltage surge suppression (TVSS), output panels, and power control, and provide more advantages.

A PDU usually includes the following components.

Offline Transformers: Dual input breakers should be considered to allow a temporary connection to be made, allowing maintenance or resource redistribution without shutting down critical loads.

Transformer: As close to the load as possible to reduce common-mode noise from ground to neutral and reduce the difference between voltage source ground and signal source ground. When the transformer is located inside the PDU unit, it is the closest location.

Transient Voltage Surge Suppression (TVSS): The efficiency of the transient voltage surge suppression (TVSS) device will be greatly improved when the wire length is as short as possible, preferably less than 200m. By providing the transient voltage surge suppression (TVSS) in the same device as the

distribution panel, the efficiency can be improved.

Distribution Panel: The panel can be mounted in the same cabinet as the transformer or a remote power panel can be used if more panels are required.

Metering, monitoring, alarms and remote control: When providing a traditional panel system, it usually means a large space requirement.

Emergency Power Off (EPO) control.

A single-point grounded bus should distribute power to critical loads using power distribution units (PDU). Panels or PDU "sidecars" may be secondary fed where additional branch circuits are required. Two redundant PDU should be provided to power each rack, preferably each powered by a different UPS system; single-phase or three-phase computer equipment should be provided with a rack-mounted fast-transfer switch or static switch fed from each PDU. Alternatively, single- and three-wire equipment may be provided with dual-fed static switch PDUs fed from separate UPS systems, although this arrangement provides slightly less redundancy and flexibility. Consideration should be given to color- coding of signage and feeder cables to distinguish A and B distributions, e.g., all A-sides white and all B-sides blue.

A circuit should not serve more than one rack to prevent a circuit failure to multiple racks. To provide redundancy, each rack and cabinet should have its own unique, two dedicated, 16A, 220V circuits from two different power distribution units (PDU) or power panels. For high-density racks, higher amperage capacity may be required. Some new servers may require one or more, single-phase or three-phase sockets with a rated current of 5OA or higher. Each socket should be identified with the PDU or circuit number that serves it.

Installation of power distribution equipment and line laying issues.

On the premise of determining the layout of equipment in the machine room, equipment installation and wiring are carried out in accordance with the use of electrical equipment and design drawings.

Equipment installation. Machine room power distribution cabinets, UPS power supply cabinets installed on the ground; power distribution box, lighting distribution box bottom edge from the ground 1.4m wall mounted; according to the equipment load capacity and distribution in the machine room, cabinet (box) within the configuration of the components to the arrangement of the orderly, firmly installed, neatly arranged lines, wired correctly, marked obviously, good appearance, inside and outside the clean. Single-phase, three-phase circuits, with small vacuum circuit breakers, such as C65N and other line protection switch. Auxiliary equipotential grounding busbar is set inside the box. The base of the power supply cabinet and other electrical devices should be firmly fixed with the floor of the building. There is no residue in the electrical junction box, and the cover plate is neat, tight and close to the wall. The installation height of the same type of electrical equipment should be the same. The electrical equipment in the ceiling should be installed in a convenient place for maintenance. Special power distribution devices should have obvious signs and indicate the frequency and voltage. Concealed lighting boxes or switch panels are installed at convenient locations on the wall near the entrances and exits of the machine room. Split air-conditioning sockets are set at 1.8m above the ground on the wall inside the machine room.

Reliable grounding. The metal frames and foundation steel of the main distribution cabinet, UPS power cabinet, power distribution box, and lighting distribution box must be reliably grounded (PE) or zeroed (PEN). The grounding terminals of the door and frame are connected with bare copper wire. The wiring inside the cabinet and box is neat. The operating current of the leakage protector in the lighting distribution box is not more than 30mmA, and the operating time is not more than 0.1s. The grounding (PE) or zeroing (PEN) branch line must be connected to the grounding (PE) or zeroing (PEN) main line separately and must not be connected in series. The neutral line (N pole) at the output end of the UPS power cabinet must be connected to the grounding main line directly led by the grounding device for repeated grounding, and the grounding resistance must be less than 4Ω. When the height of the lamp is less than 2.4m from the ground, the accessible exposed conductor of the lamp must be reliably grounded (PE) or zeroed (PEN), and there should be a special grounding bolt and mark. When the external power supply is connected to the power management room of the computer room, the metal sheath of the cable should be connected to the grounding device; the armored signal cable and shielded signal line introduced from outside the building should also be protected from lightning strikes before entering the weak current machine room to avoid lightning strikes and high-frequency electromagnetic interference from entering the room along the building's outer wall or lightning protection lead. The shielding layer of the coaxial cable must be grounded together with the casing.

(1)devices should have obvious signs and indicate the frequency and voltage. Concealed lighting boxes or switch panels are installed at convenient locations on the wall near the entrances and exits of the machine room. Split air-conditioning sockets are set at 1.8m above the ground on the wall inside the machine room.Maintenance and test power outlets should be set up in the mainframe room, and the two should be clearly differentiated signs. Test power outlets should be powered by the mainframe power system. Other rooms should be appropriately set up maintenance power outlets. Single-phase maintenance power circuit in the power management room wall 0.3m from the ground to set up maintenance power outlets, prohibit the use of more than 2kW high-power inductive power tools. If it is necessary to use such tools and three-phase maintenance equipment, the construction of mobile switchboards should be used to connect the power supply from the power or lighting distribution box near the floor where the machine room is located.

(2) Line laying. The power supply distance should be as short as possible, mainly for the sake of power supply safety. The computer power supply room should be close to the main machine room equipment. The low-voltage distribution line under the raised floor in the main machine room should use copper core shielded wire or copper core shielded cable. The power lines, signal lines and communication lines in the machine room should be laid separately, arranged neatly, tied and fixed, and the length should be left with a margin. The distribution lines led out of the UPS power distribution box (cabinet) should be laid under the raised floor of the machine room to the back of each row of cabinets and wiring racks through a thin-skinned steel pipe or flame-retardant PVC pipe, and then laid under the raised floor of the machine room to the back of each row of cabinets and wiring racks. They should be led up through the raised floor with wire holes, and protected by pipes and large metal guide-type socket ducts, cabinets or wiring racks. The wiring behind the console or equipment table should be fixed with metal guide-type socket ducts with bolts and installed on the back of the equipment table 0.1~0.3m away from the raised floor.

Signal cables from cabinets and patch panels to various devices under the raised floor should be led to the equipment from the raised floor threading holes around the equipment or in the main room from the equipment (note that the raised floor threading holes should not be shared with power lines, and the spacing should be greater than 0.1m). Signal cables should not be laid along the walls of the computer room to prevent crossing with strong wire pipes. The power lines under the raised floor should be as far away from the computer signal lines as possible, and avoid laying them side by side. When it cannot be avoided, appropriate shielding measures should be taken. The signal lines between desktop devices are short-line (length greater than 3m) and should be laid openly along the desktop at the back of the equipment, but should not be suspended in the air on the back side of the equipment table; long-line (length greater than 3m) should be turned down (up) from the raised floor threading holes and laid under the raised floor through thin steel pipes. The lighting load and ordinary air-conditioning load in the computer room are respectively led out of the power and lighting circuits from the power management room. The lighting and air-conditioning load lines are laid along the ceiling or wall to avoid the weak power room.

(3) Reliable grounding. The metal frames and foundation steel of the main distribution cabinet, UPS power cabinet, power distribution box, and lighting distribution box must be reliably grounded (PE) or zeroed (PEN). The grounding terminals of the door and frame are connected with bare copper wire. The wiring inside the cabinet and box is neat. The operating current of the leakage protector in the lighting distribution box is not more than 30mmA, and the operating time is not more than 0.1s. The grounding (PE) or zeroing (PEN) branch line must be connected to the grounding (PE) or zeroing (PEN) main line separately and must not be connected in series. The neutral line (N pole) at the output end of the UPS power cabinet must be connected to the grounding main line directly led by the grounding device for repeated grounding, and the grounding resistance must be less than 4Ω. When the height of the lamp is less than 2.4m from the ground, the accessible exposed conductor of the lamp must be reliably grounded (PE) or zeroed (PEN), and there should be a special grounding bolt and mark. When the external power supply is connected to the power management room of the computer room, the metal sheath of the cable should be connected to the grounding device; the armored signal cable and shielded signal line introduced from outside the building should also be protected from lightning strikes before entering the weak current machine room to avoid lightning strikes and high-frequency electromagnetic interference from entering the room along the building's outer wall or lightning protection lead. The shielding layer of the coaxial cable must be grounded together with the casing.

After the above cables enter the machine room, a metal junction box (box) should be installed, and the metal (shielded) outer skin of the cable should be connected to the lightning arrester or surge suppressor (SPD), and then connected to the equipotential grounding busbar of the machine room with a copper core insulated wire with a cross-sectional area of not less than 16mm2. This can effectively suppress the electromagnetic interference signal received by the cable, thereby ensuring the quality of signal transmission. The signal line sent out from the machine room should be laid along the wall and in the ceiling using a metal wire trough to avoid being parallel and close to other electrical pipelines. Try to avoid air conditioning, fire protection, heating and water supply and drainage pipelines, and the distance between them should be implemented in accordance with relevant specifications. The metal cable tray and its bracket and the metal cable conduit for introduction or extraction must be reliably grounded (PE) or zeroed (PEN), and must comply with the following regulations:

(1) The metal cable tray and its bracket should be connected to the grounding (PE) or zeroing (PEN) trunk line at no less than 2 points along the entire length.

(2) The copper core grounding wire is connected across both ends of the connecting plate between the cable trays, and the minimum allowable cross-sectional area of the grounding wire is not less than 6 square millimeters.

(3) The grounding (PE) or neutral (PEN) wires are not connected in series between sockets.

Our experienced engineers will follow the above practices during implementation to better handle the reliability and safety of the power supply in the computer room, and ensure that signal cables of various voltages and frequencies are laid safely, isolated from each other, neatly and beautifully, and easy to maintain and manage.