The common test used in determining the reliability of cable insulation is tan delta or loss angle testing. This test helps the technician determine if the cable is still in good condition or needs to be replaced.
Tan delta measures the reliability of insulators in cables based on the fact that they act like a capacitor. Passing an AC current through a good cable should shift the test current by 90 degrees. The presence of contaminants changes the capacitive characteristics and allows resistive currents to flow. The phase angle is measured by dividing the IR by IC. A good cable should should have an angle of nearly zero. A wide angle indicates high resistive currents due to insulator deterioration.
If you need a tan delta bridge, you might want to check out the TD30 from HV Diagnostics. It’s a portable tan delta bridge that features an air insulated, solid-state design which makes it ideal for field use. This bridge is suitable in conjunction with the HVA30 DC/ VLF test set.
Get the equipment you need for tan delta testing from Protec Equipment Resources. We supply tan delta bridges and VLF hipot test sets at affordable rental fees. Contact us today for a tan delta test equipment quote.