Paint film continuity testing used to use some offline testing methods, such as voltage mercury method, Japanese salt water method, low-voltage electrolyte method, etc., which are not suitable for online testing of enameled wires during the production process.
The enameled wire paint film continuity online detection system currently used by most electromagnetic wire manufacturers is a non-contact detection method based on DC high-voltage electric field sensors.
The basic principle is to generate DC high voltage through a DC high voltage circuit and connect it to a cylindrical metal conductor in the high voltage electric field sensor, so that a high voltage electric field is generated inside the cylindrical metal conductor.
Driven by the take-up wheel, The enameled wire passes through the high-voltage electric field at high speed.
When the electric field is strong enough, corona is generated on the surface of the enameled wire. If the enameled wire with defects in the paint film passes through it, local causes will be formed between the metal conductor - the enameled wire - the take-up wheel. Leakage current generated by discharge. By dynamically measuring the changes in the leakage current of the enameled wire, the defect location and severity of the enameled wire can be accurately measured and recorded.
When this method is used for detection, there is no contact between the enameled wire and the sensor part during the entire process, so there will be no additional damage to the enameled wire.
It is very suitable for online detection of enameled wires running at high speed on the production line. Moreover, the metal conductor in the high-voltage electric field sensor is approximately cylindrical, and the electric field generated is basically the same in all directions, so the detection capability in all directions is basically the same, the detection sensitivity is high, and missed detections are less likely to occur.
Of course, users of electromagnetic wires can only use offline testing, that is, using a paint film continuity tester. Compared with online testing testers, because it is only a semi-envelope state test, the ability to detect defects is slightly weaker. However, in view of the randomness of sampling, it is basically possible to qualitatively determine the performance compliance of electromagnetic wires.