The EDC system, having different stators configurations, performs different Dielectric Strength Test in DC Voltage. For example, in the case of AST320/W Stator Tester or ATT320/W Transformer Tester or AAT320/W Armature Tester or ATS320/W Generator Tester or AMT320/W - PAE320/W Motor Tester that have integrated the appropriate options, it is possible to perform the following tests:
1. Winding(s) versus Ground
2. Winding versus Winding (when the distinct phases are not internally connected, and the related terminals are accessible)
3. Thermal Protector versus Ground
4. Thermal Protector(s) versus Windings
5. Other elements (for example, terminals of a possible brake or fan or other mounted on the motor) versus Ground
6. Other elements (for example, terminals of a possible brake or fan or other mounted on the motor) versus the Windings of main Motor/Stator.
During the test, the EDC system performs the following controls:
- Measurement of the total current and comparison between the current measured value and the maximum acceptable current value set in the program parameters. The test result is passed only if the current during the test is lower than the maximum acceptable current set in the program parameters.
- Check that set testing voltage is applied to the stator under test. This is very important to ensure that the stator stack is connected to the high-voltage generator. This control can be realized reading directly the testing voltage or checking indirectly the capacity value present between the testing points.
The Dielectric Strength Test with DC Voltage is used mainly in case of high-power stators, where the capacitive current results to be high and in whichever case higher than the maximum current that the eventual available AC High Voltage source could generate (30mA, 100mA, 500mA, 1000mA). The testing voltage must be 1,41 times the testing voltage used with an AC Voltage source.
The Picture shows the principle scheme of the dielectric strength test in DC voltage measurement.