Communication DC power supply and its maintenance
① Communication section.
The mains power input for the communication section is generally 2-channel 380V three-phase four wire AC input, and sometimes 2-channel 220V single-phase AC input is also used when the power capacity is small to ensure reliable power supply. To prevent lightning strikes and overvoltage damage, lightning arresters should be installed at the input end of the mains power supply. Commonly used ones include ordinary zinc oxide lightning arresters and OBO lightning protection modules; Due to the fact that lightning protection here mainly protects against surge voltage caused by non direct induced lightning strikes, the current carrying capacity of the lightning arrester is generally selected between 15-20KA, and the residual voltage is around 1.5KV, which can effectively protect the power equipment. To achieve interlocking and automatic switching of two input AC power sources, an AC switching device needs to be installed, using mechanical or electrical interlocking methods. However, it should be noted that it is not allowed for two AC power sources to be simultaneously connected or disconnected at any time. After switching devices, the AC input is divided into rectifier module input and AC branch output. The AC branch output provides power for other AC electrical equipment in the computer room, such as computers, UPS, etc.
② The rectifier part.
The rectifier is the most important component of communication DC power supply, and the power quality of communication DC power supply mainly depends on the electrical indicators of the rectifier. It completes AC-DC conversion and supplies power to communication equipment in parallel current sharing mode, while also providing constant current and voltage limiting charging for the battery pack and power supply for the monitoring module. All communication DC power supplies now use modular high-frequency switching rectifiers, which have the advantages of small size, high efficiency, modularity, high power factor, wide input voltage range, low noise, high reliability, and can be equipped with electric hot plugging; The high-frequency switch rectifier module used in power communication DC power supply is generally single-phase 220V AC input, with a power factor of 0.99 or more, and the module capacity is generally 20A/-48V~50A/-48V per block; In practical use, if the input is a 380V three-phase four wire AC power supply, attention should be paid to evenly distributing all rectifier modules to each phase; At the same time, in order to improve the reliability of rectifier operation, excess spare capacity should be considered in the design, and N+1 redundancy should be adopted for module configuration. There are two types of high-frequency switch rectifier modules: internal control and external control. The internal control rectifier is equipped with an independent monitoring unit that can set, detect, and display the parameters of the rectifier module. It is connected to the monitoring module of the system through RS-485 bus; The externally controlled rectifier does not have an independent monitoring unit internally and is completely controlled by the system monitoring module. If the monitoring module fails, the rectifier module will switch to autonomous operation, and its output voltage and current will follow the initial set values.
