Testing the effectiveness of electrical insulators can be done using Power factor testing. This test applies to medium and high voltage equipment such as transformers, oil filled capacitors, motors, bushings or any electrical device with an insulator. Doble Engineering is one of the leading manufacturers of Power factor testers. One popular tester is the Doble M4000 M4100 Power Factor Insulation Analyzer.
Understanding cable system configurations …
The three cables that make up a 3 phase circuit can be placed in different formations. Typical configurations include the trefoil or triangular and the flat formation. The choice will depend on several factors like screen bonding method, conductor area and available space for installation.
Typical cable formations
Capacitance and Dissipation Factor (C&DF) test equipment can sometimes be limited by their power supply when testing highly capacitive objects. An example of power system apparatus that might fall into this category would include large motors, generators or cabling. Test specimens that have a characteristically higher capacitance value will sometimes achieve a maximum output current from the test equipment at less than the desired test voltage. By appropriately positioning a resonating inductor that is adjusted to resonate with the capacitance of the test object, the range of charging current from the test equipment can effectively be extended to accommodate testing of more capacitive test objects.