Simultaneous PD & Tan Delta Cable Testing

“Simultaneous Partial Discharge and Tan Delta Measurements: New Technology in Cable Diagnostics”

At the 2018 IEEE PES Transmission & Distribution Show in Denver, CO, Dominique Bolliger from HV TECHNOLOGIES, Inc. wrote and presented a paper at the Poster Session on April 18th. 

The paper focused on new technology available that allows for partial discharge AND tan delta testing to be conducted simultaneously on medium voltage cables for diagnostic purposes, thus significantly reducing testing time and downtime of the testing cable.

Abstract: In this paper, a focus was placed on the ability to decrease the amount of testing time while monitoring tan delta and PD simultaneously. Healthy and unaged cables do not need to be subjected to unnecessary stresses if no clear abnormalities are detected in diagnostic values. A case study was presented and able to show that testing time and costs can also be reduced for severely aged cable systems. New technology on the market allowing for the simultaneous monitoring of tan delta and partial discharge during monitored withstand testing gives utilities and test personnel time-efficient and cost-optimized testing solutions for new and service-aged cables. The result is a significant reduction in testing time and the ability to realize condition-based and cost-optimized maintenance plans.

The complete paper can be downloaded here

Featured Products in the Paper:

Frida TD – Compact high voltage VLF generator with integrated tan delta measuring function up to 24 kVRMS

PD-TaD 60 (now PD-TaD 62) – Portable PD diagnostics system for PD testing up to 44 kVRMS 

By combining the two instruments, dielectric losses in the cable and partial discharge sites can be located along the cable during a VLF cable test. This type of test is known as a Full Monitored Withstand Test, or Full MWT. A normal withstand test shows whether a cable can withstand a load over a specified test duration. The tan delta test evaluates the condition of the cable insulation and the partial discharge test shows whether PD is present in the cable and where it is located. Conducting all 3 tests simultaneously provides the most amount of information on the state of a cable’s health in one simple test routine. Moreover, another highlight of the Full MWT is the condition-based test routine. Healthy cables do not need to be tested with increased voltages for long periods of time, which helps in lowering testing costs.

Typical test sequence for a Full Monitored Withstand Test using VLF voltage and tan delta and PD diagnostics.