Coil-short-circuit measurement

Reliable detection of turn-to-turn short circuits in coils is essential for quality assurance in the winding process. A coil-short-circuit—meaning a short circuit between individual turns of a coil—can lead to failures and loss of performance. Therefore, precise coil-short-circuit testing is an integral part of modern production and testing processes.

Methods of coil-short-circuit testing

Traditionally, coil-short-circuit are detected using the surge test. In this method, voltage pulses from an external source are applied to the winding. The resulting damped oscillation is characteristic of the particular coil and, in the event of a fault, shows deviations in frequency and amplitude. Alternatively, there are methods in which the coil is used as part of a resonant circuit, allowing measurement without external high voltage.

The coil-short-circuit measurement developed by GDG Testsystems utilizes the self-induction of the test coil: The required voltage pulses are generated directly by the inductance of the coil itself, eliminating the need for external pulse sources. The optimal measurement parameters are automatically determined through a trial run.

Measurement principle and evaluation

• An integral is calculated from the voltage pulses generated in the coil, which serves as the measurement variable for fault detection.
• In the case of a coil-short-circuit, the integral of the affected coil is significantly damped.
• Evaluation is performed by comparing the integrals:
  • Coils of the same design and position are compared with each other.
  • Individual coils can be compared to mean values or stored reference values.
  • Regression analysis of the integrals enables a position-independent reference comparison.
• Even a single shorted turn can be reliably detected in this way.

Advantages of the method

• Automated test parameters: Measurement parameters are automatically learned and stored for different types of test samples.
• High sensitivity: Even the smallest coil-short-circuits are detected.
• Additional monitoring: The influence of the quality of laminated stack sheets on the total inductance can also be monitored.

Conclusion

The innovative coil-short-circuit measurement from GDG Testsystems offers an automated, highly sensitive, and process-reliable solution for detecting coil-short-circuits in coils. It is suitable both for individual testing and for integration into automated production lines, meeting the increasing demands for quality and efficiency in coil production.