With regards to partial discharge test ECG KOKUSAI

Production Engineering Department
Quality Assurance Department
Maintenance Department
Development Department

It plays a key role in the production lines and quality inspection processes of all electrical products that use wound coils, such as motors, transformers, solenoids, and ignition coils. In particular, for inverter-driven motors used in EVs and HVs (electric and hybrid vehicles), partial discharges (corona discharges) generated inside the windings due to high voltage spikes are a major cause of insulation degradation. As a result, the DWIT-05PD—which can perform partial discharge testing simultaneously with conventional layer short testing—is gaining attention as the new standard for manufacturing quality assurance. It has been adopted in mass-production inspection lines across a wide range of industries, including automotive, home appliances, industrial equipment, and robotics, and is capable of performing 100% inspection inline.

By applying a high-voltage pulse to a coil and comparing the response waveforms, layer shorts are detected with high accuracy. Furthermore, this single unit can simultaneously perform conventional impulse winding tests (for rare short detection) and partial discharge (PD) tests. Thanks to its proprietary detection circuit, the system highly sensitively detects partial discharges—which are subtle signs of insulation coating degradation—and completes the reliability evaluation of coils for inverter-driven motors, such as those used in EVs and HVs, in a single process. In recent years, there has also been growing interest in insulation testing for materials such as insulating paper and coatings; this system is capable of handling everything from small-lot, high-variety production to 100% inspection of mass-produced items, as well as insulation evaluation of film materials.