AC Line Traps for High-Frequency Power Line Communication to Prevent Unwanted Transmission

  • 16 Dec, 2019

Line traps are a key component in Power Line Carrier Communication (PLCC) systems to prevent unwanted signal transmission. Line traps are also known as a high-frequency stopper or wave traps, they are used in power transmission and distribution networks around the world as a maintenance-free parallel resonant circuit. Line traps are series-connected to the high voltage ac power lines used for transmitting high-frequency signals between 40 kHz and 500 kHz. An AC line trap prevents the transmission of high-frequency carrier signals to an unwanted destination typically substation. This helps in preventing undue loss of carrier signal power under all power system conditions.

Line Traps are the cylinder-like structure with three major components: the main coil, the tuning device, and the surge arrester (protective device). The surge arrester and the tuning devices are mounted inside the main coil which is covered with a cylindrical bird barrier. The main coil is made from aluminum cables for a low impedance path for the electricity flow while a tuning device consists of coils, capacitors, and resistors and is used for blocking frequencies. The protective device is the third component of a line trap that is connected in parallel with the main coil and the tuning device to protect them from high-voltage levels. Line traps are designed to withstand the rated power frequency current and the short circuit current to which the power lines are subjected.

How does it work?

A line trap is a maintenance-free parallel resonant circuit connected in series with the transmission line. It is used to create high impedance in the carrier frequency range of 40 kHz to 500 kHz and prevents these high-frequencies from entering into unwanted destinations and prevents signal losses. This protects the power system components from high-frequency damages that are designed to operate at 50 or 60 Hz. The line trap’s inductive reactance offers high reactance to high-frequency signals but a low reactance to mains signal that allows the passage to main current & block the unwanted high-frequency currents. To protect electrical equipment like transformers and breakers, line traps are usually connected at the entrance of substation in the incoming line.

Using the high-frequency line traps, substations communicate with each other through the power lines at the same time as they transmit electrical power as they use different frequencies to separate power signals from messages being sent.

An AC line trap can be used indoor as well as outdoor as per the requirements. Many manufacturers offer to fulfill special requirements for any custom installation. You can contact any reputed and experienced manufacturer in the business to order line traps as per your requirements. Before installing a line trap to any location, make sure that it is clean with no harmful gas, steam, electric conductivity, and explosive dust around for safety purposes.