Important Notice:
HVI's line of Tan Delta Transducers, used as accessories to the VLF-E Series of Very Low Frequency AC testers, has been updated. The TD-34E model has been discontinued. Moving forward, the TD-65E will now be offered as an accessory to either VLF-E model. See Product Change Notice Here.

Click here to get more details.

Tan delta (Tan δ, TD) testing, also referred to as dissipation factor or loss angle, is a method used to measure the deterioration level of shielded MV/HV cable insulation. The results indicate the extent of contamination, damage, or water tree infusion in the insulation.

TD measurements are employed to achieve the following goals:

• Establish baseline readings on new installations
• Monitor cable conditions over time
• Compare the condition of multiple cables to aid in prioritizing cable replacement and/or rejuvenation programs
• Determine if additional tests are warranted

Tan delta testing is conducted with the cable off-line. A VLF AC test instrument supplies the test voltage to the cable while the TD device records the results. It is a diagnostic test, meaning it is not a VLF AC withstand test, which carries a high risk of cable failure. By performing TD testing, cables can be rated as highly, moderately, or slightly degraded. The test voltage is incrementally increased in steps while readings are monitored to avoid potential cable failure if the TD values signal severe degradation.

TD testing is cost-effective, easy to perform, and the results are straightforward to interpret.

Tan Delta Diagnostics Information

You will get efficient and attentive service from Hengfeng.

Tan Delta (TD), also known as Dissipation Factor or sometimes even Power Factor, is an excellent diagnostic method that gauges the quality of dielectric insulation used in electrical apparatus. By analyzing the dielectric losses in the insulation, the TD Series of test instruments equip testing engineers with a versatile high-voltage diagnostic system suitable for testing MV cables such as XLPE, EPR, PE, and PILC. Furthermore, other electrical apparatus like capacitors, transformers, and large rotating machines can also be diagnosed.

For MV and HV cables, Tan Delta measurements are the most effective and widely used diagnostic technique for detecting water trees and water degradation, the most prevalent aging mechanism and cause of failure in old extruded insulated cables. These degradation mechanisms often go unnoticed with other diagnostic techniques such as Partial Discharge. Tan Delta tests can also be conducted at test voltages below the device's normal operating voltage under test. This minimizes the risk of cable insulation failure, which could otherwise occur during a normal "hipot" or elevated voltage test when conducted on weak or highly aged insulation. Insulation defects can be identified before they result in cable failure while in service.

Tan Delta diagnostic measurements can also be combined with an acceptance or maintenance VLF withstand test to deliver an intelligent or SMART VLF test. By analyzing the Tan Delta data in real-time, the test engineer can shorten the testing time on cables with good characteristics while extending the testing time on cables with poor insulation properties. Similarly, the operator can prevent test failures by identifying highly degraded cables at or below the normal operating voltage.

The test engineer gains a clearer understanding of the remaining life of their cable assets, allowing them to better plan and prioritize their cable replacement or rejuvenation program and thereby enhance overall reliability.

The TD Series of instruments work seamlessly with the HVA Series of VLF high voltage test instruments. Some TD systems are external and interface with the HVA as separate devices, while others are integrated into the HVA System. Every TD system includes corona suppression shields, an NIST traceable calibration certificate, the Industry "Standard" TD Control Center software, all housed in a rugged carry case. TD systems are available up to 200kV!

If you want to learn more, please visit our website tan delta test equipment.