IWT-5000A winding tester is a coil (such as voltage transformer, inductance, motor) testing instrument that tests self-insulating property of the coil. The in?uences of winding materials, magnetic materials, and framework, also extra fabrication decreases the insulating property of coil layers along with the jumpers and jacks. The IWT-5000A adopts the technology of high-speed sampling rate to store the sample waveform of the standard (master) coil in the instrument. By comparing the waveform results of the test coil to the master, the defect in the DUT can be found easily. Moreover, the IWT-5000A judges the quality of the testing coil according to the parameter set by the user.