High voltage VLF testing of power cables

Eager, G. S.; Katz, C.; Fryszczyn, B.; Densley, J.; Bernstein, Bruce

doi:10.1109/61.584323

Cited by 46 publications

(6 citation statements)

References 4 publications

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“…The interest of VLF method at the beginning was mainly to ensure that the insulation system could take this over voltage by performing overpotential testing [13][14][15][16]. Eager et al found that the breakdown voltage of laboratory aged XLPE cable at 0.1 Hz was approximately similar to that at 60 Hz.…”

Section: Introductionmentioning

confidence: 99%

“…Eager et al found that the breakdown voltage of laboratory aged XLPE cable at 0.1 Hz was approximately similar to that at 60 Hz. Testing at 0.1 Hz appeared to be a satisfactory alternate to DC testing method due to very little damage to the insulation [13]. However, later research results showed that the breakdown voltage of healthy insulation at 0.1 Hz was about twice of that at 50 Hz [15].…”

Section: Introductionmentioning

confidence: 99%

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Review of Partial Discharge Activity Considering Very-Low Frequency and Damped Applied Voltage

2021

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When detecting the presence of partial discharge (PD) activity in the insulation system in high-voltage equipment, the excitation voltages at variable frequency have been widely used instead of power-frequency (50/60 Hz) sinusoidal voltage in order to reduce the charging power. This work reviews the relevant research on PD activity at very low frequency (VLF) method, including sinusoidal or cosine-rectangular voltage shape, and damped AC (DAC) method. Based on the research history and development status, some major PD characteristics, such as PD inception voltage (PDIV), PD amplitude, PD charge, PD phase-resolved pattern, and several hot issues, such as surface charge decay and statistical time lag, have been discussed. Moreover, the advantages, disadvantages, and applied conditions of two reviewed methods has been summarized. Finally, the prospects have been made on the main development trends of this research field in the future.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Review of Partial Discharge Activity Considering Very-Low Frequency and Damped Applied Voltage

2021

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“…Although the charge current can be ignored, DC voltage is not a satisfactory substitute because it changes the distribution of electric field and the alternative characteristic of voltage waveform. Also DC voltage leads to the accumulation of space charge in the equipment and may cause damage to the XLPE insulation during tests [1]. Without all these disadvantages above, the low frequency comes to the sight of engineers.…”

Section: Introductionmentioning

confidence: 99%

Characterization and comprehension of corona partial discharge in air under power frequency to very low frequency voltage

Zhou¹,

Zhou²,

Zhang³

2018

Plasma Sci. Technol.

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For the partial discharge test of electrical equipment with large capacitance, the use of lowfrequency voltage instead of power frequency voltage can effectively reduce the capacity requirements of test power supply. However, the validity of PD test under low frequency voltage needs to be evaluated. In order to investigate the influence of voltage frequency on corona discharge in the air, the discharge test of the tip-plate electrode under the frequency from 50 to 0.1 Hz is carried out based on the impulse current method. The results show that some of the main features of corona under low frequency do not change. The magnitude of discharge in a positive half cycle is obviously larger than that in a negative cycle. The magnitude of discharge and interval in positive cycle are random, while that in negative cycle are regular. With the decrease of frequency, the inception voltage increases. The variation trend of maximum and average magnitude and repetition rate of the discharge in positive and negative half cycle with the variation of voltage frequency and magnitude is demonstrated, with discussion and interpretation from the aspects of space charge transportation, effective discharge time and transition of discharge modes. There is an obvious difference in the phase resolved pattern of partial discharge and characteristic parameters of discharge patterns between power and low frequency. The experimental results can be the reference for mode identification of partial discharge under low frequency tests. The trend of the measured parameters with the variation of frequency provides more information about the insulation defect than traditional measurements under a single frequency (usually 50 Hz). Also it helps to understand the mechanism of corona discharge with an explanation of the characteristics under different frequencies.

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“…Additionally, the space charge accumulated may cause unexpected damage to insulation during a DC withstand test. Above all, low frequency voltage is an appropriate option [10].…”

Section: Introductionmentioning

confidence: 99%

Feature Extraction and Comprehension of Partial Discharge Characteristics in Transformer Oil from Rated AC Frequency to Very Low Frequency

Zhou

Huang

et al. 2018

Energies

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The reactive current can be reduced effectively by decreasing the frequency of the voltage in partial discharge (PD) test, especially for equipment with large capacitance. Thus, the cost and volume of the test power supply can be economized. To figure out the difference of PD characteristics in transformer oil between rated alternating-current (AC) frequency (50 Hz) and low frequency, tests are conducted from rated AC frequency to very low frequency (0.1 Hz) based on impulse current method. The results show that with the decrease of frequency, the inception voltage increases. The maximum and mean magnitude of discharge and pulse repetition rate first increase slightly, then decrease obviously. The main features of the variation of phase resolved PD (PRPD) patterns, discharge statistical patterns (phase distribution of maximum and mean discharge magnitude, pulse repetition rate q max-φ, q mean-φ, n-φ; and number distribution of discharge magnitude n-q), and their characteristic parameters (skewness S k + , S k − ; kurtosis K u + , K u − ; asymmetry A sy ; and correlation coefficient C c) are depicted in detail, which should be paid attention to when using low frequency voltage. The inner mechanism for these variations is discussed from the aspects of the influence on electric field distribution and discharge process of frequency. Additionally, the variation trend of PD characteristics with the decrease of frequency can provide more information about insulation defect, which can be the supplement for discharge mode recognition.

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High voltage VLF testing of power cables

Cited by 46 publications

References 4 publications

Review of Partial Discharge Activity Considering Very-Low Frequency and Damped Applied Voltage

Review of Partial Discharge Activity Considering Very-Low Frequency and Damped Applied Voltage

Characterization and comprehension of corona partial discharge in air under power frequency to very low frequency voltage

Feature Extraction and Comprehension of Partial Discharge Characteristics in Transformer Oil from Rated AC Frequency to Very Low Frequency

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