Answer / pundlik wanwe

48v Dc is used in the telecommunication circuit.

Answer / rabi

A negative line voltage helps to reduce the corrosion from
electrochemical reactions occurring on a wet telephone line.
Also -48v DC is more stable than +48 volit, so -48 V is
preferred.

Answer / subra

in -48v dc system positive + is earthed. Negative- is
giving to the equipment.Normally in automobile dc system
negative is earthed.positive is giving to equipment.in
positive grounding system we can avoid corrossion on
terminals.

Answer / anant gupta

it's true that telecommunications equipments operates on the
negative 48 volts DC.


how can we get any voltage while we are grounding the
positive terminal. pls give details.....

Answer / shri..

Thanks for repply


But why not using + ve 48 volt????

Answer / muralichppl

what is difference between + 48V and - 48V and how can we we
get individually

Answer / avinash

Even if a high supply current comes,the equipment can
compensate due to -ve voltage

Answer / maxiquiet

why do we prefer -48 volt instead of -24volt or -12 volt
etc. ??

Answer / jitender kotwal

first understand what -48 volt means,it means that when we
grounded the nagtive termnal of supply making it to zero
potential means nagative supply, in communacations we use
negative voltage to reduce the noise and hum level.

Answer / hemant

WHEN CLOUDS STRIKE THEY PRODUCE -VE CHARGE ,& FOR DISCHARGE THEY NEED THE ZERO POTENTIAL AT EARTH.IN TELECOM WE R GROUNDING THE -VE TERMINAL OF SUPPLY TO MAKE IT ZERO POTENTIAL .IF WE GROUND THE +VE TERMINAL THEN ALL THE EQUIPMENT WILL DAMAGE OR FIRED BECAUSE CLOUD WILL CHOOSE LOW RESISTANCE
+VE CHARGED ANTENAS.THAT IS THE REASON WE USE -48V.

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