18650 lithium ion battery

　　Study on the scheme of overall replacement of switching power supply

　　Any kind of equipment has its own life cycle. At the late stage of the equipment life cycle, the equipment will inevitably experience aging, reduced efficiency, increased faults, etc., which is not conducive to production safety and is prone to related failures. causing significant losses. In addition, due to the equipment manufacturer, various spare parts in the later life cycle cannot be guaranteed, which brings certain difficulties to the maintenance and repair of the equipment. Therefore, expired equipment needs to be updated and transformed to ensure the safety of production on the existing network.

　　-48V DC is the main power specification for transmission and switching equipment. Some data equipment also uses -48V DC. Therefore, DC switching power supply [1] is the main power supply for communication equipment. According to "China Mobile Communication Power Supply, Air Conditioning and Monitoring and Maintenance Management Regulations (2008 Edition)" Chapter 3, Section 1, Article 19 stipulates that the update cycle of high-frequency switching rectifier conversion equipment is 12 years. Upon expiration, professionals must be organized to formulate a replacement plan and implement it safely [2].

　　Since most of the communication equipment that the switching power supply is responsible for powering are core network elements, which require 24-hour uninterrupted working power, the switching power supply must ensure that the output is not interrupted during the overall replacement process, and the entire process cannot have any adverse effects on the load. Threaten network security. The overall switching energy replacement plan is difficult and risky. China Mobile has been established for 10 years, and its switching power supply equipment has begun to enter the replacement period. However, it does not have much experience in overall replacement. This article introduces the overall replacement plan of the switching power supply in detail, and fully verifies its feasibility through specific projects, and provides a method for reference.

　　Shanghai Mobile successfully implemented the overall replacement and renovation projects of Siemens and Delta switching power supplies in Caoxi Building and Wusheng Building in 2008 and 2011 respectively. The author summarizes the entire replacement process and key points to note, and makes relevant introductions here.

　　1 Comparison of replacement options

　　The -48V DC switching power supply system is shown in Figure 1. There are basically the following basic solutions for the overall replacement and update of switching power supply equipment. The specific advantages and disadvantages are analyzed as follows:

　　1.1 Replacement in situ

　　Key points of the plan: Install a temporary power supply system in the computer room, connect it in parallel with the old system, cut all the loads to the temporary system, install the new power supply system in place, and connect it in parallel with the temporary system again, cut all the loads. Make your way back to the new system and remove the temporary power system.

　　Advantages: The overall coordination of the computer room does not damage the original power supply system, has little impact on communication equipment, is suitable for replacing a small number of power supplies, has low investment, and is suitable for old computer rooms without redundant installation locations.

　　Disadvantages: It is the most difficult, including the formulation of the plan and the specific construction implementation, which requires being very familiar with the system. The construction workload is large and involves a large number of non-stop power cutovers.

　　1.2 Transposition replacement

　　Key points of the plan: After installing a new system in the computer room, connect it with the old system, re-route new cables to all loads or reuse old cables and extend them, then cut over all loads online to the new system, and then dismantle the old system. .

　　Advantages: The construction is less difficult and the workload is significantly less than the in-situ replacement solution. It is suitable for computer rooms with abundant installation locations.

　　Disadvantages: The output cables in the original power supply system will be re-routed due to routing changes, or the original cables will be extended through cable multiplexing and other means, leaving hidden dangers and requiring large investments.

　　1.3 Retain the original DC power distribution panel and only update the rectifier module part

　　Key points of the plan: Install a temporary power supply system in the computer room. After parallel connection with the old system, remove the original rectifier module screen, install a new module screen, and then remove the temporary power supply system after parallel connection with the DC power distribution panel.

　　Advantages: The construction workload is small, the load familiarity requirement is low, the investment is small, and it is less difficult to replace products of the same model from the same manufacturer.

　　Disadvantages: Since the manufacturer's equipment is constantly being updated, the same model of product is likely to have been discontinued. The connection and installation methods of the module screen and DC screen in this solution need to be redesigned, which is difficult. If the products are from different manufacturers, it will involve the mixed use of system detection, control and alarm systems, which is more difficult. Moreover, the internal equipment cycles of the power system are inconsistent, and there will be subsequent update workload.

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