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Safeguarding Your Power Components and Isolated Components
How to Reduce Insulation Quality Abnormality (Partial Discharge)
in Power Components and Isolated Components?
When there is a void inside the insulation material or when there is an air gap between the insulation materials, the void or the air gap is prone to partial discharge (PD) under the normal operating (working) voltage, which can lead to insulation degradation and cause the insulation quality to be abnormal. Why does PD often appear at the voids inside the epoxy or the air gap between enameled wires? Because the relative permittivity of air is a lower than that of the insulation material, the capacitance of the void or air gap is lower than that of the insulating material, and therefore, the void or air gap will have a relatively high proportion of voltage. Additionally, under the same distance condition, the breakdown voltage of the void or air gap is lower than that of the insulation material. This electrical discharge, which occurs in the void or air gap (partial defects) while other insulation materials in series are remaining normal, is called partial discharge (PD).
Ca：Equivalent capacitance of the insulation material (path without any void between the electrodes)
Cc：Equivalent capacitance of the void
Cb：Equivalent capacitance of the insulation material (path with void between the electrodes)
When a sufficient test voltage is applied on the device under test (DUT), the charge quantity of PD is measured (in pC) by using PD measurement for checking whether the insulation material of the DUT has any potential risk of abnormal insulation quality. Therefore, applying the test voltage, which is slightly higher than the maximum rated working voltage of the component, for the PD test ensures the component's quality and reliability (no continuous PD) for long-term operation under normal operating voltage.
IGBT and SiC-MOSFET, both power semiconductor devices, are used in various fields such as electronic products, industrial equipment, aerospace, military equipment, railway systems, energy applications, smart grids, electric vehicles, etc. They are frequently used in high-power conversion, large-current power conversion and power control circuits, which may have an operating voltage with several kilo-volts. Because they will be switched ON and OFF very frequently, there is a PWM (Pulse-Width Modulation) high voltage difference across between the gate and collector or between the gate and drain of the module, and as well as between the module and heatsink. When the high voltage is across the insulation materials that contain voids, air gaps, or cracks, there is a higher likelihood of PD occurring. After long-term operation, the insulation material will be gradually degraded, which will eventually lead to insulation failure of the material and cause product damage.
Partial Discharge Tester Chroma 19501 ↗
The Chroma 19501 series complies with the requirements of IEC 60270 for partial discharge (PD) measurement and integrates the testing methods specified by the standard into the instrument. It provides AC withstand voltage testing (up to 10kVac) and partial discharge measurement (up to 6,000pC), effectively identifying insulation quality defects in high-voltage/power components, optocouplers, digital isolators, etc.. This ensures the quality and reliability of components during long-term operation.
▲ 19501+A195005 Partial Discharge Tester + HV Module
▲ 19501+A195004 Partial Discharge Tester + HV Module
▲Isolator UHV Test System Sample Chroma 1950
The Chroma 1950 can control 1 to 16 units of the 19501 in a master-slave configuration with phase-synchronized high-voltage output. It also collects, analyzes, and statistically processes test data to generate reports. Additionally, it offers tailored integration with customers’ automated production systems, making it easier and more convenient to pair and integrate the 19501 with automated production equipment.
▲ ▲Isolator UHV Test System Sample
