Why use -48V for communication base station power supply?
3G equipment macro station is still -48V based, but most of the 3G business in the interior, and operators in order to reduce site costs, indoor AP-POE and outdoor RRU+BBU coverage will become the main way of 3G distribution. The time available for -48V power supplies may be worth considering.In addition, with the massive growth of data services, large room IDC will become an urgent demand, direction and focus and the power supply safety and cost control is the IDC room we explore, promote the use of high voltage DC power supply scale will gradually expand.
2G macro stations generally use -48V, which is mainly due to historical reasons. The earliest communication network used was the telephone network, which was powered by the telecommunications office. The 48V was chosen as far as possible to improve the user's end-to-end distance (36V is a safe voltage, more than too insecure). Later, in order to be compatible with early equipment and cost reduction, the local communications equipment was powered by -48V. Negative power supply system, positive grounding is only used. The original saying is that there are a lot of negative charges in the air. According to the knowledge of electrochemistry, the positive grounding can adsorb negative ions in the air, thus protecting the shell of the telecommunication equipment from being corroded. In fact, this statement is not quite right. Galvanic reactions and electrolytic reactions can cause equipment to rust, but because they are microscopic in the equipment, they have little impact. For example, the network of non communication systems is negative grounded (for example, the computer you are using), but it is not rusty. And -48V internal isolation through the DC/DC, DC/DC output is negative ground, nor see single board corrosion rust. So no matter which pole is grounded, it is the same.
At present, the communication power voltage level is mainly divided into DC -48V (+24V) and AC 220/380V, which is in the initial stage, but the promising DC 380V appears.
