If electrical signals are used, what kinds of power supply voltages and control voltages are commonly used in the control system?

As the "heart" of the communication system, the communication power supply system has an unparalleled important position in the communication bureau (station). It contains a wide range of contents, including not only 48V DC combined communication power supply system, but also DC/DC secondary module power supply, UPS uninterrupted power supply and communication battery. The core of communication power supply is basically the same, which is based on power electronics. Through stable control loop design and necessary external monitoring, energy conversion and process monitoring are finally realized. Communication equipment needs power supply equipment to provide DC power. The security and reliability of power supply are important conditions to ensure the normal operation of communication system. Simply put, the communication power supply system is divided into AC and DC parts. The AC system has two phases and three phases, which are 220V and 380 V respectively. There are +24V and -—48V DC. The early wired telephone used "* * * electricity", and the power supply of the telephone was provided by the telephone exchange through the telephone line, which played the roles of power supply, voice transmission, ringing, off-hook signal and so on. The power supply used in the early telephone office was the original lead-acid battery. At that time, the material and structure were suitable for positive grounding, and its voltage was a multiple of the basic (single battery) voltage 1.2 volts. According to the capacity of equipment components and lines at that time, and in order to ensure the long-distance communication distance and local telephone safety, the power supply chose positive grounding, and the voltage was 48 volts (60 volts), so the system was negative grounded. At present, the telephone and its switch have experienced the replacement of magnetic-* * * electricity-automatic switching (electromechanical electronics)-program-controlled switching. In the replacement of these systems, except the magnet system, the power supplies of other systems are compatible at first, and the power supply voltage and grounding polarity remain unchanged. Switching power supply is a kind of power supply which uses modern power electronics technology to control the time ratio of switching tube on and off and maintain stable output voltage. Switching power supply generally consists of pulse width modulation (PWM) control IC and MOSFET. With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. At present, switching power supply is widely used in almost all electronic equipment because of its small size, light weight and high efficiency, and it is an indispensable power supply mode for the rapid development of electronic information industry. The output voltage depends on where it is used and how much V it can output. Common DC voltages in the market are 5V, 6V, 9V, 12V, 15V, 24V, 48V and 240V.