Have a question? Get an answer!

Do you have any doubts about the power frequency (50 or 60 Hz) power factor/dissipation factor (PF/DF) test results obtained from your HV assets?

In the field, it is common to measure PF/DF at power frequency and obtain results within acceptable limits. However, these measurements can be inconclusive because they may not change until insulation is severely degraded. Compared to power frequency PF/DF, 1 Hz is up to 10 times more sensitive to insulation changes and provides immediate confirmation of insulation degradation or contamination.

Is 1 Hz also temperature dependent? Is correction to 20 °C possible?

Absolutely. Assessment of PF/DF may be incorrect without proper temperature correction. However, temperature correction tables do not apply to 1 Hz measurements. Further, even if temperature correction tables could be used, IEEE C57.12.90 states that no single correction curve will fit all cases. To address this, Megger’s DELTA4000 and TRAX + TDX use measurements of PF/DF from 1 Hz to 505 Hz to provide Individual Temperature Correction (ITC), temperature correction based on the actual condition of the insulation.

Do I need a separate test connection and/or different software for 1 Hz and ITC tests?

No! 1 Hz and ITC tests use the same test connection as 10 kV power frequency tests. The software is preconfigured to execute the tests and display results alongside the power frequency results.

How does 1 Hz power factor/dissipation factor (PF/DF) support immediate insulation assessment?

At lower frequencies, the sensitivity of dielectric changes due to moisture or contamination increases. This means that 1 Hz values will be higher and increase sooner than line frequency power values. Therefore, 20 °C corrected 1 Hz and power frequency measurement is an effective tool to identify early and advanced degradation and potential failure the insulation of HV components such as transformers and bushings.

Which instruments do you need for 1 Hz testing?

1 Hz PF measurement can be performed with a dedicated DFR instrument (IDAX 300 series), or with the same equipment used for 10 kV power factor/dissipation factor testing (DELTA 4000 or TRAX + TDX).

Why does 1 Hz testing make a big difference?

1 Hz is a proactive way to validate the commonly used power frequency PF/ DF results.

a. Mismatch in the assessment of power frequency vs 1 Hz results properly corrected to 20 °C by ITC algorithm is indicative of progressive degradation of the insulation material.
b. It provides confidence on the dielectric assessment and elevates the safe and reliable operation of HV assets.
c. Asset managers and maintenance specialists rely on trustable test results to assure extended service life of critical components within the electrical network.

Who are you?

1 Hz is the technology capable to validate, line frequency power factor / tan delta tests. The objective is to extend the service life of assets without depending of any trending or database and even more, avoiding any other additional investments, to know the real condition of the insulation of their assets.

Find personalized content for you

Asset man

Service con

Other

Digital Substation

Software, data communication and control, etc., is standard in modern substations. Though the development and implementation of IEC 61850 since mid 2000’s, the way to design, configure and run the substations have changed. This IT influence brings many advantages but also introduce new challenges to the industry.

Distributed energy resources

The power network is facing a huge change moving from centralized, large generation stations to smaller DER. Accurate communication leading to quick and correct decisions will be key in the development of the smart grid. The relay protection in DERs, like wind and solar farms, uses rather basic protection functions but their design creates other challenges when it comes to testing.

Special and advanced applications

Advanced relay testing refer to protection functions that isn’t straight forward parameters such as current, voltage or frequency. Even though that is exactly what is measured and calculated, the advanced protection category is either presented in another format, such as impedance for distance protection, or require complex test setup as transformer differential.