requirement analysis

In the construction of electronic information, the power supply and distribution system of the computer room is the basic facility. The modern computer room is developing constantly, and the requirements for the construction of the computer room are also increasing. The power supply in the data computer room has a very high requirement for its stability, and it also requires that the modern computer room can work all year round. Such a UPS power supply solution for the computer room is a very important part of the power supply system of the computer room. Even in case of mains power failure or grid failure, it is necessary to ensure that there is power supply for the machine room, which requires that the power supply system has emergency security power supply that can make the unit power off; therefore, the machine room needs to be equipped with UPS power supply for the machine room, so as to provide the power supply for the machine room, which is the guarantee for the operation of the information system.

The choice of UPS power supply solution in the computer room is based on the equipment needed in the computer room. For example, those equipped with monitoring, server and switch belong to capacitive load, and the high-frequency machine is selected when purchasing UPS power supply; for printing machine, automation equipment, automatic access control system, etc., they belong to inductive load, and need to be equipped with power frequency UPS power supply. Select the appropriate UPS according to the size of the load. The load is generally 0.6-0.7 of the ups capacity. The backup time is configured according to the needs of customers!

Basic configuration scheme

1、 Requirements for UPS front power supply system

UPS can provide high-quality power supply with high voltage stability, frequency stability and low waveform distortion to the load, and can achieve uninterrupted power supply when switching with static bypass. However, to achieve this, the quality of its previous power supply can not be ignored. We should consider the following aspects when designing the front power supply system of the communication room:

(1) The power quality of the former power supply system should not be too poor, and the voltage and frequency should be stable in the normal range.

(2) The front power supply system should not be equipped with other frequent starting loads, such as frequently used elevators, frequently opened air conditioners, etc.

(3) The capacity of AC generator set in the former power supply system shall be appropriately enlarged.

2、 Determination of UPS capacity

According to the load capacity and nature, choosing appropriate UPS can not only ensure the power supply quality of UPS, reduce the failure rate, but also save investment and improve economic benefits. Generally speaking, the determination of UPS capacity is mainly to meet the needs of the current load. At the same time, several factors should also be considered:

(1) The influence of load properties on the output power of ups.

(2) The capacity of UPS should not be too large compared with the load to make it operate under excessive light load.

(3) The capacity of UPS should not be too small, so that it is in the state of heavy load operation for a long time.

(4) In the case of large area of communication room and continuous expansion of load by stages, the medium and long-term development trend shall be properly considered when configuring UPS capacity in the early stage, and the models that can be parallel or multi machine operation shall be selected in the selection, so that when the medium and long-term load capacity increases, the output capacity can be expanded through UPS parallel. Accordingly, when the ups I / O distribution panel is configured, multiple UPS input switches and load shunt switches in the medium and long term shall be reserved for future expansion.

3、 Electrical isolation and grounding of power supply system

Generally speaking, there are differential mode noise and common mode noise in the power grid, which have different degrees of interference to the normal operation of the computer. In addition, the offset of the zero line potential will also affect the operation of the computer, so measures should be taken to reduce these effects when considering the UPS power supply scheme. For large computer network and other important loads, the power supply system should try to use UPS with power frequency isolation transformer.

4、 Correctly configure UPS backup battery

In order to ensure that when the power grid is cut off, UPS can also be used to continue to power the computer, the configuration of backup battery is important.

The selection of battery capacity shall follow the following: that is, the battery shall supply power to the inverter within the backup time, and under the rated load, the battery voltage shall not drop below the voltage reduction allowed by the inverter. When arranging the equipment in the machine room, the battery pack shall be close to the ups host as far as possible, the connection length shall be shortened, and the sectional area of the connection shall be increased, so as to reduce the self inductance of the connection and the line voltage drop. The battery pack can be installed in the battery cabinet or in the open battery rack. The former is beautiful. Clean, but the load-bearing requirements of the floor are high, the latter can be decentralized load-bearing, and good heat dissipation, but covers a large area, easy to accumulate dust, which brings inconvenience to maintenance.

5、 Increase power supply through redundancy

In order to improve UPS power supply, a variety of UPS redundant connection modes can be adopted, all of which have advantages and disadvantages. When considering the scheme, the appropriate mode shall be selected according to the actual load situation.

At present, there are three ways of redundant connection:

(1) Dual host and slave hot backup.

Connect the output of UPS1 as a slave to the bypass input of another UPS2 as a host, which is powered by UPS2 during normal operation, and UPS1 is in backup. When UPS2 fails, the load is switched to UPS2 bypass, and UPS1 is responsible for the load supply task.

(2) Power sharing and parallel backup.

The system runs two or more UPS inverter units in parallel. Normally, two (or more) inverters supply power to the load equally at the same time. When one of them fails, the UPS is disconnected from the system, and the load current required by the user is re supplied by the remaining inverter according to the new share.

(3) Parallel hot backup.

In this system, two UPS's battery input, rectifier output and inverter output are connected in parallel and share bypass. Normally, two rectifiers supply power to two inverters at the same time and charge two batteries. One inverter is selected to supply power to load through inverter output static switch. Two rectifiers and inverter are standby for each other. Only when two inverters fail at the same time , the system switches the load to the common static bypass, and the municipal power continues to supply power to the load.

6、 The power supply system shall