Singapore DC Power Supply

Singapore DC Power Supply: Why is the Telecommunication power supply -48V?
There are 2 meanings here:
(1) Why is the polarity negative power (that is, positive ground)?
(2) Why is the voltage -48V (-36~ -72V)?
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Let’s talk about the second question first. Using a -48V power supply is for historical reasons. The earliest communication network used was the telephone network, and the telephone was powered by the telecommunications bureau. The choice of 48V was to maximize the distance between the user and the end office under the conditions at that time (36V is a safe voltage, too much is unsafe). Later, in order to be compatible with early equipment and reduce costs, the central office communication equipment still uses -48V power supply.
As for the grounding of the casing of the equipment (connected to PGND), this is for the purpose of protection, and the electric charge accumulated on the equipment is quickly discharged to the ground, so as not to damage the equipment and staff.
As for the grounding of the casing of the equipment (connected to PGND), this is for the purpose of protection, and the electric charge accumulated on the equipment is quickly discharged to the ground, so as not to damage the equipment and staff.
You may also learn through the media that there are devices that use a -24V power supply system, which some modern internal devices use for design convenience. The output voltage of the power supply is generally measured to be 26.8V.
Generally, the equipment is required to work normally within the voltage fluctuation range of ±20%. For -48V system equipment, the working voltage range is -38.4V ~ 57.6V, but we generally require the working range -36V ~ -72V. The main consideration is that the -48V system equipment should be compatible with the -60V power supply system, which requires -48~ -72V. In this way, the combination is required to operate in a voltage range of about -36V ~ -72V.
The -48V power supply system is only a communication power supply standard adopted by my country and most countries. Not all countries use this standard. For example, Russia uses a -60V power supply system, and some countries use a -24V power supply system. If the product is to be sold in these regions, it is necessary to take into account these different standards. The standard of mains is also different in the world. For example, my country and Europe use 220V mains system, and the United States and Japan use 110V mains.
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Best Plus Power is a manufacturer and provider of dependable high efficiency power electronics, energy conversion systems and power supplies. Best Plus Power solutions include a complete line of high-efficiency rectifiers, inverters and DC power systems for mission critical applications. With over 10-Years experiences supporting customers in more than 60 countries, Best Plus Power is focused on bringing reliable power solutions to customers across all applications and environments, which specialize in Battery Chargers, Power Inverters, Power Supplies / Rectifiers, DC / DC Converters, Frequency Converters, and other Power supplies.
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