As for as I've heard, -ve volt is used because to avoid any interfernce due to noises as noise voltages used to be in positive side. Why 48V is used?
waleed - 4th April 2004 (07:31 GMT)
sorry dear ahmad i miss understand your question, I thought you are asking about the voltage (why 48 instaead 24)not why - 48and not + 48,in case of -48 the +ve polarity is connected to the ground(equipment chassise)and the dc current flows from +ve to -ve so in this way the we will avoide this current stream carring distortion and interference to log in the electronic circuits gaining high reliability and pure DC supply.
Ahmad - 1st April 2004 (00:25 GMT)
Can some experts answer for this question..
Sanjeev - 31st March 2004 (09:52 GMT)
Sammour u r right , negative voltage is used to reduce the corrision
waleed - 28th March 2004 (08:37 GMT)
i think -48v is used instead of 24v because we have high loaded power to decrease the loaded current and lowering the power supply cable thickness(24vdc used in the bts back up battery).
Abdalla Sammour - 28th March 2004 (08:13 GMT)
I think that you meant by your question why the negative voltage is used, if so my answer is the chemical effect is less than positive voltage.
Ahmad - 23rd March 2004 (18:42 GMT)
Though this topic has already been discussed, I'd like to get cleared about the fact that "Why -48V is used as power for telecom eqipments?"