Influence of the permitted parameter variations on the determined Q IEC value according to IEC 60270 (original) (raw)
Related papers
Guide for Electrical Partial Discharge Measurements in compliance to IEC 60270
For better understanding the background of the current standard IEC 60270, WG D1.33 " High-Voltage Testing and Measuring Techniques " decided the edition of a Technical Brochure, which is intended as a guideline for engineers dealing with conventional electrical PD measurements. In this context it should be noted that currently the new standard IEC 62478 is under preparation, which covers non-conventional electromagnetic and acoustical PD detection methods. These topics, however, are outside of the scope of this brochure. Partial discharges are defined in IEC 60270 as: " localized electrical discharges that only partially bridges the insulation between conductors and which can or cannot occur adjacent to a conductor. Partial discharges are in general a consequence of local electrical stress concentrations in the insulation or on the surface of the insulation. Generally, such discharges appear as pulses having a duration of much less than 1 µs. " From a physical point of view self-sustaining electron avalanches may happen only in gaseous dielectrics. Consequently, typical discharge types occurring in ambient air, such as glow, streamer and leader discharges, may also happen in gaseous inclusions due to imperfections in solid and liquid dielectrics. The pulse charge of glow discharges is in the order of few pC. Streamer discharges may create pulse charges ranging from about Partial discharges (PD) have been recognized as a harmful ageing process for electrical insulation at the beginning of the last century when the HV technology was introduced for the generation and transmission of electrical power. Since that time numerous papers and books appeared, dealing with the physics and recognition of partial discharges. First industrial PD tests of HV apparatus were introduced at the beginning of 1940. The method applied was based on NEMA 107, which specifies the measurement of radio influence voltages (RIV) expressed in terms of µV. One disadvantage of this method is, however, that the RIV level is weighted according to the acoustical noise impression of the human ear, which is not correlated to the PD activity. Therefore, the IEC Technical Committee No. 42 decided the issue of a separate standard on electrical PD measurement associated with the PD quantity apparent charge, which is expressed in terms of pC. The first and second editions of the IEC Publication 270 appeared in 1968 and 1981, respectively. IEC 60270 [High-voltage test techniques – Partial discharge measurements , third edition], published in December 2000, covers besides classical analogue instruments also requirements for digital measuring systems. Moreover, the maintaining of specific characteristics of PD measuring systems by the user in a record of performance is recommended.
Applied Sciences
The insulation condition of HVDC grids consisting of cable systems, GIS, and converters should be monitored by partial discharge (PD) analysers using artificial intelligence (AI) tools for efficient insulation diagnosis. Although there are many experiences of PD monitoring solutions developed for the supervision of the insulation condition of HVAC grids using PD analysers, there are no standardised requirements for their qualification available yet. The international technical specification TS IEC 62478 provides general rules for PD measurements using electromagnetic methods but does not define performance requirements for qualification tests. HVDC and HVAC PD analysers must be tested by unambiguous test procedures. This paper compiles experiences of using PD analysers with HFCT sensors in HVAC grids (cable systems, GIS, and AIS) to define a qualification procedure for HVAC systems. This procedure is applicable to HVDC grids (cable systems, GIS, AIS, and converters) because the part...
IET Conference Publications, 2009
Authors share their experience with 15-channel continuous Partial Discharge (PD) monitors applied to medium voltage rotating machines, apparatus and substation equipment, using variety of PD sensors. Real life examples illustrate the condition-based paradigm "measured-inspectedconfirmed-repaired" that clearly purports this totally nonintrusive and effective on-line diagnostic technology. Use of stator RTDs as PD sensors offers an inexpensive solution for attenuation problems, especially in large rotating machines. Continuous monitoring assures that high variations of PD activity will not be overlooked in comparison with periodic tests. The discussed technology will help in making intelligent and accurate maintenance decisions, significantly improving effectiveness and quality of insulation repairs.
Preliminary partial discharge measurements with a computer aided partial discharge detection system
2009 International Conference on Electrical and Electronics Engineering - ELECO 2009, 2009
Partial discharges (PDs) can be destructive to electrical insulation as they may degrade the material in time. Consequently, studies have been made to develop efficient systems for PD measurements and monitoring. Due to the complexity of PDs as well as factors that can affect PD characteristics, the research on PD measurement is still active. In this study a set off preliminary laboratory measurements of discharges, produced in laboratory environment with various test objects, were performed to evaluate understanding of the theory related to partial discharge and the relationship to early detection of insulation deterioration. Beside these, the common problems with recent computer aided partial discharge detection systems were tried to be identified such as detect level selection, exact PD inception voltage (PDIV) and PD extinction voltage (PDEV).
Metrological Qualification of PD Analysers for Insulation Diagnosis of HVDC and HVAC Grids
Sensors
On-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of...
Sensors, 2018
Partial discharges (PD) measurement provides valuable information for the condition assessment of the insulation status of high-voltage (HV) electrical installations. During the last three decades, several PD sensors and measuring techniques have been developed to perform accurate diagnostics when PD measurements are carried out on-site and on-line. For utilities, the most attractive characteristics of on-line measurements are that once the sensors are installed in the grid, the electrical service is uninterrupted and that electrical systems are tested in real operating conditions. In medium-voltage (MV) and HV installations, one of the critical points where an insulation defect can occur is inside metal-clad switchgears (including the cable terminals connected to them). Thus, this kind of equipment is increasingly being monitored to carry out proper maintenance based on their condition. This paper presents a study concerning the application of different electromagnetic measuring techniques (compliant with IEC 62478 and IEC 60270 standards), together with the use of suitable sensors, which enable the evaluation of the insulation condition mainly in MV switchgears. The main scope is to give a general overview about appropriate types of electromagnetic measuring methods and sensors to be applied, while considering the level of detail and accuracy in the diagnosis and the particular fail-save requirements of the electrical installations where the switchgears are located.
IEEE Transactions on Dielectrics and Electrical Insulation, 2006
The IEC 60093 Standard, prepared by the International Electrotechnical Commission in 1980, sets up methods of measurements, determination and calculation of volume and surface resistivities of solid dielectrics. The document contains some editorial mistakes as well as content-related inaccuracies that require revisions. Besides corrections of obvious editorial mistakes it is suggested to introduce some content-related improvements. The most important remarks given in the paper are associated with the following problems: 1) shunting of the current meter by the resistance between guarding and guarded electrodes; 2) significant influence of the electrodes made of conducting rubber on volume resistivity measurement results; 3) errors associated with application of simplified expressions for resistivitiy calculations (volume resistivity for tubular samples, surface resistivity for samples with circular electrodes); 4) increase of the effective surface of the measuring electrode (margin width determination and consideration). Finally, proposals of alterations of particular clauses of the standard, supplemented with appropriate justifications, were given in the paper.
2016 International Conference on Condition Monitoring and Diagnosis (CMD)
Analysis of the types of defects and the degradation modes in different insulation materials of highvoltage (HV) electrical systems has shown that the presence of partial discharges (PD) is a very common characteristic in all of them. Once PD activity is detected, the identification and localization of the associated type of defect is very important to evaluate whether the discharges are harmful or not. During the last two decades, different approaches have been developed and applied to PD measurement and processing techniques to deal with the most common problems arising in on-site and on-line measurements, such as: high levels of background noise, appearance of interferences, simultaneous presence of different PD sources and the difficulty of locating the site of the defects and to identify them. This paper proposes a measuring method together with the implementation of three signal processing tools in order to overcome all these difficulties that appear in on-site and on-line tests. The measuring method has been implemented to evaluate in an on-site practical experience the insulation condition of the power equipment in a GIS substation. After the application of the method, important insulation defects were detected, identified and localized, on time to avoid uncontrolled failures in the electrical system of the substation under test. I.
Power quality monitoring and sample size analysis beyond EN 50160 and IEC 61000-4-30
22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013), 2013
Possibility for storing electrical energy in any significant quantity is very limited. Measurement and evaluation of the quality of the supplied Voltage (power) has to be made at the instant of its consumption. Power Quality analysis, monitoring and assessment is a very complex task, since the supplier and user, whose sensitive electrical equipment is also a source of disturbances, have different perspectives.