The 48V power supply system used by the communication equipment in the communication base station is to increase the distance from the user end to the local end as much as possible (36V is a safe voltage, it is unsafe to exceed too much); later, in order to be compatible with the early 48V communication equipment and reduce costs, the central office communication equipment will be replaced over time. 48V power supply system is still used.
The communication base station chooses -48V level as the power supply voltage of communication equipment, the main reasons are as follows:
1) 48V voltage is relatively safe. For example, the resistance of the human body is 50kΩ. When the power supply voltage is -48V, the maximum current flowing through the human body is 48/50000=0.96mA, which will not affect human life.
2) The positive electrode grounding of the power supply system of the communication base station can reduce the corrosion phenomenon of the positive electrode of the battery.
3) In the early days, the communication base station used the earth as the loop of communication equipment, thus saving wire.
4) The power supply system of the communication base station adopts 48V voltage level higher than 24V, which is conducive to energy transmission, thereby reducing the energy loss of the line.
5) The power supply system of the communication base station adopts positive grounding, which can reduce the corrosion of the grounding device.
The shell of the communication equipment needs to be connected to the ground through an electrical connection, so that the charge accumulated on the communication equipment can be quickly released to the ground, so as to ensure that the communication equipment will not be damaged and the personal safety of the operator will not be affected; the equipment of the communication base station is basically It uses a 48V power supply system, and the actual measured DC voltage is 53.5V. In addition, considering the reliability of the communication equipment, it needs to be equipped with a 48V battery system as a backup power supply.
At the same time, in order to ensure the reliable charging function of the battery system, ensure The power supply system voltage of its communication base station needs to be slightly higher than the battery system voltage.
Based on the above, the communication base stations applicable to some countries including China adopt -48V power supply system, not only to better meet the voltage level requirements of communication equipment, but also to improve the utilization rate of energy transmission and operation, and at the same time to ensure the safety of communication equipment Reliable grounding; however, not all countries use -48V voltage as the power supply system of communication base stations.
If some countries use -60V power supply system, -24V power supply system, etc., it is necessary to choose the appropriate voltage power supply system according to the characteristics of each region.