scholarly journals Study on Quantitative Correlations between the Ageing Condition of Transformer Cellulose Insulation and the Large Time Constant Obtained from the Extended Debye Model

Energies ◽  
2017 ◽  
Vol 10 (11) ◽  
pp. 1842 ◽  
Author(s):  
Yiyi Zhang ◽  
Jiefeng Liu ◽  
Hanbo Zheng ◽  
Hua Wei ◽  
Ruijin Liao
Keyword(s):  
Time Constant ◽  
Large Time ◽  
Debye Model ◽  
Ageing Condition ◽  
Cellulose Insulation

Restoration of terahertz continuous wave image obtained by continuous scan mode with large time constant

2014 ◽  
Vol 53 (32) ◽  
pp. 7735 ◽  
Author(s):  
Xiao Lou ◽  
Lei Hou ◽  
Gaoyuan Guo ◽  
Wei Shi
Keyword(s):  
Time Constant ◽  
Large Time ◽  
Continuous Wave ◽  
Wave Image

New Method for Assessment Ageing Condition of Oil Impregnated Insulation Pressboard Based on Frequency Domain Spectroscopy

2014 ◽  
Vol 513-517 ◽  
pp. 323-327 ◽  
Author(s):  
Jian Hao ◽  
Jin Fu ◽  
Pei Guo ◽  
Gao Lin Wu ◽  
Qian Wang ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Moisture Content ◽  
Frequency Domain ◽  
Condition Assessment ◽  
New Method ◽  
Time Saving ◽  
Interpolation Curve ◽  
Ageing Condition ◽  
Cellulose Insulation

It is important to assess the condition of the cellulose insulation in transformer. However, taking paper samples from a transformer is both impractical and destructive. In this paper, a new method for assessment ageing condition of oil impregnated insulation pressboard based on frequency domain spectroscopy (FDS) was proposed. The FDS measurements were taken on oil impregnated insulation pressboards with five ageing levels at moisture content of 1.22%, 2.06%, 3.02% and 3.87%. The dielectric loss of all the samples were calculated bytanδ (f)interpolationandthe ageing condition assessment database which contains data of five ageing levels and 1%-4% moisture content was built. It is found that thetanδ (f)interpolation is more sencentive to ageing and moisture. It could realize the ageing condition assessment by comparing thetanδ (f)interpolation curve with the curves in the database.The assessing result of the middle-low main insulation life of a 220kV transformer valided that it is effective and time saving to use the new method for ageing condition assessment.

The Simulation Study on Transformer Oil-Paper Insulation Polarization Spectrum

2013 ◽  
Vol 385-386 ◽  
pp. 1175-1178
Author(s):  
Jun Qiang Zhang ◽  
Tao Zhao ◽  
Yun Peng Liu
Keyword(s):  
Time Constant ◽  
Simulation Analysis ◽  
Debye Model ◽  
Diagnostic Methods ◽  
Transformer Oil ◽  
Equivalent Model ◽  
Polarization Spectrum ◽  
Paper Insulation ◽  
Transformer Insulation ◽  
Non Destructive

Return voltage diagnostic method is an effective method of non-destructive diagnosis in transformer insulating state. The current study is that through experiments get polarization spectrum to analysis the transformer insulating state, but not yet carried out the influence of various factors to the experimental results. So, based on the Debye model and specific parameters comes from one equivalent model of the actual transformer, this paper using RVM methods to simulation analysis maximum return voltage and dominant time constant under different factors. Simulation results show that the diagnostic methods that combine maximum return voltage value with dominant time constant can preferably reflect the transformer insulation state.

Rapid Measurement of Power Transformer Winding DC Resistance

2013 ◽  
Vol 333-335 ◽  
pp. 22-26
Author(s):  
Xiao Fei Luo ◽  
Xian Xia ◽  
Kai Jun Wu
Keyword(s):  
Time Constant ◽  
Large Time ◽  
Power Transformer ◽  
Resistance Mutation ◽  
Transition Process ◽  
Measurement Circuit ◽  
Rapid Measurement ◽  
Transformer Winding ◽  
Simulation Results ◽  
Dc Resistance

Aim at the electric power transformer with inductance is large, resistance is small, the inherent characteristics of the large time constant, a fast measurement scheme of power transformer winding DC resistance is proposed. The scheme adopts the increase the measurement circuit loop resistance mutation method, in which the circuit transition process from a time constant is forced to another time constant, to realize the rapid measurement of winding DC resistance in power transformer. Simulation results show the effectiveness of the scheme.

Phosphoreszenz der Entladungsrohrwand (Kovarglas) als Beitrag zur Lichtemission abklingender Plasmen

1971 ◽  
Vol 26 (11) ◽  
pp. 1897-1900 ◽  
Author(s):  
T. D. Märk ◽  
H. J. Oskam
Keyword(s):  
Time Constant ◽  
Plasma Volume ◽  
Discharge Tube ◽  
Large Time ◽  
Glass Tube ◽  
Helium Plasma ◽  
Decay Period

Emission having a large time constant has been measured recently in the decay period of plasmas produced in nitrogen and helium-nitrogen mixtures. Whereas the fast decaying emission during the early afterglow originates from the plasma volume, it was suspected that emission responsible for the large time constant (10 to 15 ms) was not due to emission processes involving nitrogen. The present studies relate to detailed measurements of this phenomenon in a decaying helium plasma produced in a Kovarglass built discharge tube. It will be shown that this slow decaying emission is due to phosphorescence of the walls of the glass tube.

scholarly journals An exponent-scalable method for very small capacitance spread and large time constant of switched-capacitor integrator

2019 ◽  
Vol 16 (3) ◽  
pp. 20181075-20181075
Author(s):  
Quan Li ◽  
Yan Li ◽  
Xiaosong Wang ◽  
Xin Liu ◽  
Yu Liu
Keyword(s):  
Time Constant ◽  
Large Time ◽  
Switched Capacitor ◽  
Small Capacitance
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