An analysis of the influence of microclimate on partial discharge activity in emissions of electric machines in the conditions of industrial operation – own research

2013 ◽  
Vol 62 (4) ◽  
pp. 629-648
Author(s):  
Zbigniew Plutecki ◽  
Sławomir Szymaniec
Keyword(s):  
Partial Discharge ◽  
Measurement Techniques ◽  
Signal Propagation ◽  
Electrical Machines ◽  
Electrical Machinery ◽  
Factors Affecting ◽  
Discharge Activity ◽  
On Line ◽  
Major Factors ◽  
Winding Insulation

Abstract The article presents the results of diagnostic measurements of partial discharge signal propagation from the winding insulation in electrical machinery, which were performed using an on-line method. This paper describes the results of experiments and the acquired experience in the monitoring of winding insulation in high power and high voltage electrical machines which are important in industrial production processes. The authors show the measurement techniques employed in their research. Representative measurement results are presented along with their analysis. The authors use an SKF monitoring systems to measure: vibrations, temperature, and humidity, as major factors affecting partial discharge activity in the from winding insulation of electrical machines.

The prediction of voluntary intake of grazing dairy cows

1986 ◽  
Vol 107 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Lindsey Caird ◽  
W. Holmes
Keyword(s):  
Organic Matter ◽  
Measurement Techniques ◽  
Live Weight ◽  
Simple Equation ◽  
Factors Affecting ◽  
Farm Planning ◽  
Sward Height ◽  
The Mean ◽  
Major Factors ◽  
Grazing Dairy Cows

SUMMARYInformation on the total organic matter intake, concentrates supplied (C), live weight (LW), week of lactation (WL), milk yield (MY), herbage organic matter digestibility (HOMD), herbage mass, sward height (SHT) or herbage allowance (HAL) measured individually for 357 cows at one of three sites was assembled. Observed intake was compared with intakes predicted by existing intake equations and new prediction equations based on regression models or regression and least-squares constants were developed. Major factors affecting intake were MY, LW, WL, C and HAL or SHT. Although HOMD was correlated with intake, better predictions were obtained when HOMD was omitted. There were differences between sites possibly associated with differences in measurement techniques.The predictive value of some existing equations and new equations were tested against independent sets of data. A simple equation (A) based on MY and LW (Ministry of Agriculture, Fisheries and Food, 1975) gave satisfactory average predictions but the mean square prediction error (MSPE) was high. The equations of Vadiveloo & Holmes (1979) adjusted for bias gave a relatively low MSPE. The preferred new equations for grazing cattle included MY, LW, WL, C and HAL or SHT, and their MSPE were similar to or lower than for indoor equations.The discussion indicates that a simple equation (A) would give adequate predictions for farm planning. The more detailed equations illustrate the inter-relations of animal with sward conditions and concentrate allowances. Predicted intakes may deviate from actual intakes because of short-term changes in body reserves.

scholarly journals Comparison of Low and High Frequency Partial Discharge Measurements on Stator Windings

2019 ◽  
pp. 134-138
Author(s):  
Greg C Stone ◽  
Howard Sedding
Keyword(s):  
High Frequency ◽  
Partial Discharge ◽  
Low Frequency ◽  
International Standards ◽  
Very High Frequency ◽  
Stator Windings ◽  
Advantages And Disadvantages ◽  
On Line ◽  
Winding Insulation

Partial discharge (PD) testing has been used for over 60 years primarily as a method to assess condition of the stator winding insulation in motors and generators rated 6 kV and above. More recently it has also been used by some machine manufacturers as a means of assuring the quality of the insulation on single winding elements (coils and bars). Although both on-line and off-line tests mainly use a high voltage capacitor to detect the PD, the PD measuring systems in use work either in the low frequency (LF) regime (less than about 1 MHz) or in the very high frequency (VHF) (30-300 MHz) range. By reference to several international standards, published work as well as some experiments described in this contribution, the advantages and disadvantages of the two approaches are compared. Based on this work, it is now clear that off-line PD tests should be done in the LF range. For on-line tests, either method may be used, but use of the VHF method has become more widespread with machine end users, since the owners themselves can perform and interpret the results with a relatively low risk of false indications.

scholarly journals Effects of Environmental Factors on Partial Discharge Activity and Estimation of Insulation Lifetime in Electrical Machines

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 108491-108502
Author(s):  
Waqar Hassan ◽  
Ghulam Amjad Hussain ◽  
Farhan Mahmood ◽  
Salman Amin ◽  
Matti Lehtonen
Keyword(s):  
Environmental Factors ◽  
Partial Discharge ◽  
Electrical Machines ◽  
Discharge Activity

Internal On-line Partial Discharge Analysis of 68.75 MVA Generator Stator Winding Insulation

2016 ◽  
Vol 6 (5) ◽  
pp. 2088 ◽  
Author(s):  
Waluyo Waluyo ◽  
Siti Saodah ◽  
Eltha Hidayatullah
Keyword(s):  
Electric Field ◽  
Partial Discharge ◽  
Surface Discharge ◽  
Damage Effect ◽  
Stator Winding ◽  
Measuring Point ◽  
Temperature Detector ◽  
On Line ◽  
Winding Insulation ◽  
Generator Stator

<p>Partial discharge is a phenomenon of electron ionization occurs due to concentrated electric field in a different edge plane. This phenomenon will be investigated by an electric field measurement in a measuring point. The internal partial discharge will give the insulation damage effect on a generator stator winding due to void existence. This manuscript presents the measurement results of the on-line internal partial discharge on the stator winding insulation of 68.75 MVA generator. It used the resistant temperature detector method and CM2000<sup>TM</sup>. The results were classified into three conditions based on the voids in the generator stator insulation, the internal delamination and the surface discharge.</p>

scholarly journals Internal On-line Partial Discharge Analysis of 68.75 MVA Generator Stator Winding Insulation

2016 ◽  
Vol 6 (5) ◽  
pp. 2088 ◽  
Author(s):  
Waluyo Waluyo ◽  
Siti Saodah ◽  
Eltha Hidayatullah
Keyword(s):  
Electric Field ◽  
Partial Discharge ◽  
Surface Discharge ◽  
Damage Effect ◽  
Stator Winding ◽  
Measuring Point ◽  
Temperature Detector ◽  
On Line ◽  
Winding Insulation ◽  
Generator Stator

<p>Partial discharge is a phenomenon of electron ionization occurs due to concentrated electric field in a different edge plane. This phenomenon will be investigated by an electric field measurement in a measuring point. The internal partial discharge will give the insulation damage effect on a generator stator winding due to void existence. This manuscript presents the measurement results of the on-line internal partial discharge on the stator winding insulation of 68.75 MVA generator. It used the resistant temperature detector method and CM2000<sup>TM</sup>. The results were classified into three conditions based on the voids in the generator stator insulation, the internal delamination and the surface discharge.</p>

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