Power Transformers - Line Trap

edited February 2021 in Power System

Line Trap nedir, nasıl çalışır, bağlantı şekli nasıldır?

"What is Line Trap, how does it work, how is the connection method?"


  • Line trap, also known as Wave trap, is basically used to trap high-frequency signals or to stop them from entering towards the substation power side. Line traps are generally used at the substations where Power Line Carrier Communication (PLCC) systems are employed.

    What is a Power Line Carrier Communication (PLCC) system?

    In this system, as it's name implies, Power Line itself is used to carry communication. How it is done - with the help of modulation techniques.

    A modulated signal having higher frequency range is added onto the power line along with the main power transmission. Frequencies that are used to transmit power are usually 50 Hz (UK, India etc.) or 60 Hz (US). A modulated carrier signal with much higher frequency, usually within range of 24 to 500 kHz, is then impressed on either one or multiple conductors. Thus, with the help of modulation and de-modulation at either ends, communication signals are transmitted over a power line.

    What is Line Trap or Wave Trap and How does it work?

    As said, above, a Line Trap is a device/circuit which blocks high frequency carrier signals from entering into power circuits in a substation. But what exactly it is? Basically, a Line Trap is a "Parallel Resonant Circuit" i.e a parallel LC circuit with very high impedance for higher frequencies. This Line Trap circuit is connected in series with the power line.

    As this LC circuit offers very high impedance to the higher frequency signals, these signals will be flowed towards communication circuits via a coupling capacitor. The communication circuits may consist of Tx/Rx circuits and modulators - demodulators.

    Kiran Daware
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