WAVE trap : Power plants and substati**s are c**nected by high voltage power transmissi** lines which transmit power typically at 50 or 60 Hz. These lines are also used to carry communicati** and c**trol signals for the operati** of the grid (local equipment status, readings, alarms and switching signals). These signals which are of much lower voltage than the power, use high frequency carriers and Wave trap filters are employed to separate the power and communicati** signals at every receiving end.