Why inter-transformer communication is not possible in Data Communication through Powerline?

Question

If possible, how & why?

Answer 1

There are two reasons:

One reason is that, data communications generally operate at high frequencies (KHz to MHz range). The core of a transformer is designed to work at 50 or 60 Hz. Hence high frequencies get absorbed (attenuated) and do not get transferred to the secondary.

Secondly, assuming that even if data is transmitted at the mains frequency, the distribution transformers are generally step down types. While the mains voltage is in thousands of volts (HT) the amplitude of the data signal is typically in milli Volts or micro volts. Hence even if some signal gets across to the secondary, the step down ratio is much higher and for a signal which is already in micro or millivolts, the secondary signal voltage is barely usable.

However, communication is possible via powerlines by providing optical isolation converters which bypasses the data signals at transformer points and again superimposing the signal on the secondary side.

Comparitively traditional methods like wireless are far more economical and hence powerline communication methods are not popular. However they are used to communicate between substations.

Answer 2

It is possible. Some companies have trialled providing internet connections to households via the power lines.

Answer 3

There was some experiments for that but the loses are very high. most high tension wire would need capacitors to bypass the low freq transformers etc. The last I heard it was not very good .