What Is the Tan Delta Test?

The Tan Delta test is a good way of measuring cable insulation.

Tan Delta testing is a procedure used in electronics to measure how effective a cable is as an insulator. This test is key in determining if a cable needs to be replaced after heavy use.

Meaning of Tan Delta

Tan Delta, symbolized as Tanδ, is known as the Dissipation factor in the study of electrical circuits. It is defined as the ratio of useless current to useful current in an electrical system. δ in this case refers to the angle of power loss in this system.

Necessary Hardware

Two items are needed to perform a Tan Delta test: the Tan Delta Unit, consisting of a measuring unit and a loss angle analyzer; and a Very Low Frequency power source, which will provide the test voltage. A VLF control device is also used to display and adjust voltage.

Testing Process

Before the actual testing, the cable in question must be de-energized. After that is done, voltage provided to the cable from the VLF power source is increased in small increments while the measuring unit displays any values of angle loss. An angle loss value of close to zero indicates that the cable is a quality insulator, while an angle value shifted close to 90 degrees means that the cable is contaminated and is a poor insulator.

References

• High Voltage Inc,: Tan δ (Delta) Cable Testing
• Inside Power Station: Generator Tan-Delta Test