Transmission Line Test System is a new generation power transmission line frequency parameter testing system. It equips with frequency conversion testing power DFT Digital Filtering Technique which eliminates strong interference from power frequency electric field and ensures the safety of equipment convenient fast and accurate measurement. 1. Quickly and accurately test the positive sequence capacitance the positive sequence impedance zero sequence capacitance zero sequence impedance also can measure the mutual inductance and coupling capacitance between lines ; 2. High Anti-interference ability accurate and reliable measurement; 3. Easy operation equipped with large LCD and American rotating mouse and micro printer 4. Simple wiring only connecting with tested down leads to finish all line parameter measurement 5. High speed micro-controller as inner core integrated structure 6. Fast testing process one sequence parameter testing time is 1 min 7. Supplied with three groups different frequency power supply for selection: 42.5Hz/57.5Hz 45Hz/55Hz 47.5Hz/52.5Hz easily isolate the power frequency and noise wave to ensure high precision measurement of small signals.