Sunday, January 15, 2017

Why telecom power supply has -48V dc power supply?

Why telecom power supply has -48V dc power supply?

Negative sign indicates The positive grounded

he negative voltage on the line was better than positive to prevent electro-chemical reactions from destroying the copper cable quickly, if cables get wet

Low enough not to cause serious danger if somebody touches the telephone wires

What is the nominal voltage required in subscriber loop connected to local exchange?

   - 48 volts. This -48 volts is required by the copper wires to prevent it from corroded & eluded

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