
Why is 48V a telecommunications industry standard operating voltage? There are several reasons why this is the case. First, it is considered a “compromise voltage” because this voltage level is high enough to enable relatively low signal loss for transmissions over large distances and yet low enough to be considered a “safe low voltage.” Most common safety regulations internationally consider levels below 50V to be safe.
Another advantage of this voltage level is that four 12V batteries connected in series create a 48V DC backup power source, usable in the event of electrical power outage. Many central stations have elaborate arrays of 48V battery banks which may occupy even an entire room.
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