Damped AC (DAC) testing & diagnosis

Damped AC (DAC) testing & diagnosis

Damped AC Testing

Advanced DAC technology utilizes voltage testing in combination with non-destructive diagnostic methods, such as partial discharge (PD) detection and dissipation factor (tan δ) measurement of the cable system and associated accessories.


On-site testing and diagnosis of Damped AC (DAC) of power cables is:

  • A good alternative to traditional VLF and ACRT methods more sensitive and less destructive.
  • Generating in the cable insulation electrical AC stresses providing more complete information (PD localization and dielectric losses) about cable system condition.
  • Attractive from the point of view of costs, logistics and execution efforts e.g. time, transportation, installation.
  • Fulfilling testing parameters as requested by the IEC 60060-3, IEEE 400, IEEE 400.4, IEC 60060-3, IEC 60480, IEC 62067, IEC 60270, IEC 63026 and IEEE 400.3.
  • Implemented in testing recommendations in a number of regional and national bodies e.g. PTPiREE, SEP, CENELEC, UK Power Networks, UNE.
  • Since more than 20 years used for distribution and transmission of on-shore and since more that 5 years in off-shore applications in many parts of the world.

To obtain the overall technical condition of a newly installed on- and offshore power cable systems and/or to evaluate the electrical, thermal

Damped AC Testing

and mechanical service aging the following diagnostic test will be performed and the results evaluated in relation to international guidelines:

  • High voltage damped AC (DAC) over-voltage testing.
  • Partial discharge measurement and localization.
  • Dielectric losses by the dissipation factor (tan Delta) estimation.

Damped AC (DAC) technology (IEEE 400, IEEE 400.4) has the advantage of non-destructive testing and the method provides deterministic values of partial discharge (PD) activities in the cable system as well as the dissipation factor (tan Delta) of the overall cable system.

After-laying testing of a new installed HV power cable in a wind park using Dual-Side System

Long Lenght Cable Circuits

Master unit of a DAC 300 kV Dual-Side and Dual Power test system configuration

Approved testing methodology
Slave unit of a 300 kV DAC Dual-Side test system

Long-Lenght Cable Circuits

DAC testing of long lengths power cable circuits:

  • Due to its low input power demand damped AC technology makes it possible to energize very long lengths (up to 100 km) of AC and DC power cable with a high capacitance.
  • Applicable for PD-monitored testing of all types MVAC, HVAC and HVDC HV and EHV power cables.
  • Applicable for on- and off-shore after-laying / commissioning, maintenance and diagnostic testing.
  • Approved testing methodology, in accordance with on-site testing test parameters from relevant international standards and recommendations (IEEE, IEC, CIGRE).
  • Possibility of dual sided partial discharge detection on very long cable circuits lengths (up to 100 km) of power cables.
  • Due to Dual-Power (DP) energizing and Dual-side (DS) partial discharge measurement possibility to detect and to localize discharging defects on very long circuit lengths (up to 100 km) of power cables.
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