Partial Discharge Energy Measurements on Electrical Machine Insulation When Energized at Frequencies between 0.1 Hz and Power Frequency

Miller, Richard A.; Black, I. A.

doi:10.1109/tei.1979.298212

Cited by 24 publications

(9 citation statements)

References 3 publications

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“…Application of low-frequency PD measurement on machine insulation was first reported in [14,15]. However, these studies were not focused on different sources of PD and application of PRPD patterns was not popular at that time.…”

Section: Introductionmentioning

confidence: 99%

Analysis of partial discharge sources in stator insulation system using variable excitation frequency

Nair

Vishwanath²

2019

IET Science, Measurement & Technology

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Section: Introductionmentioning

confidence: 99%

Analysis of partial discharge sources in stator insulation system using variable excitation frequency

Nair

Vishwanath²

2019

IET Science, Measurement & Technology

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“…Earlier a pulse height analyser was used to study the PD magnitude distribution at different frequencies [15, 16]. These studies lacked the exploration of defect identification using low‐frequency PD measurements.…”

Section: Introductionmentioning

confidence: 99%

Identification of slot discharges in rotating machine insulation system using variable frequency PD measurement

Nair

Vishwanath²,

Rao

2018

High Voltage

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Slot discharge studies are very important from the insulation diagnosis perspective. Further in practice, testing of rotating machines with power frequency requires sources which are quite bulky and costly. Instead if the diagnosis is carried out at lower frequencies (<50 Hz), the size and cost of the test source can be reduced significantly. Therefore, it is important to know whether the study at low frequencies can be considered equivalent to study at power frequency. Hence, in this study, a slot discharge phenomenon occurring in a rotating machine insulation system was investigated experimentally at different frequencies (50, 10, 1 and 0.1 Hz). Slot discharges are known to have a distinct phase resolved partial discharge pattern for power frequency (50/60 Hz) excitation. These distinct patterns are useful in identifying the presence of slot discharge activity in rotating machines. Slot discharges were created on a 6.6 kV mica-epoxy stator coil and the slot discharge characteristics measured at different frequencies are compared. Slot discharge measurements were repeated by varying the air gap between the insulation surface and grounded steel plate. The changes in slot discharge characteristics due to the increase in air gap were found similar at all frequencies. The comparison suggests that the identification of slot discharge is also possible from the partial discharge (PD) measurement at low frequencies.

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“…R. Miller points out that with the decrease of frequency, the magnitude of discharge in the void in epoxy resin decreases [12]. Because of the limitation of measurement technology, early research mainly focuses on whether there is a significant difference of discharge characteristics between rated AC frequency and low frequency, only for evaluating the effectiveness of a withstand test under low frequency [13][14][15]. With the increasing requirement for diagnosis accuracy, recent research begins to examine the details of the difference [16,17], for example, how the frequency affects the dissipation of discharge deposited from the previous half voltage cycle [18][19][20].…”

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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Partial Discharge Energy Measurements on Electrical Machine Insulation When Energized at Frequencies between 0.1 Hz and Power Frequency

Cited by 24 publications

References 3 publications

Analysis of partial discharge sources in stator insulation system using variable excitation frequency

Analysis of partial discharge sources in stator insulation system using variable excitation frequency

Identification of slot discharges in rotating machine insulation system using variable frequency PD measurement

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

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