1、Designation: D 3382 07An American National StandardStandard Test Methods forMeasurement of Energy and Integrated Charge Transfer Dueto Partial Discharges (Corona) Using Bridge Techniques1This standard is issued under the fixed designation D 3382; the number immediately following the designation indi
2、cates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover two bridge tech
3、niques formeasuring the energy and integrated charge of pulse andpseudoglow partial discharges:1.2 Test Method A makes use of capacitance and losscharacteristics such as measured by the transformer ratio-armbridge or the high-voltage Schering bridge (Test MethodsD 150). Test Method A can be used to
4、obtain the integratedcharge transfer and energy loss due to partial discharges in adielectric from the measured increase in capacitance and tan dwith voltage. (See also IEEE 286 and IEEE 1434)1.3 Test Method B makes use of a somewhat differentbridge circuit, identified as a charge-voltage-trace (par
5、allelo-gram) technique, which indicates directly on an oscilloscopethe integrated charge transfer and the magnitude of the energyloss due to partial discharges.1.4 Both test methods are intended to supplement themeasurement and detection of pulse-type partial discharges ascovered by Test Method D 18
6、68, by measuring the sum of bothpulse and pseudoglow discharges per cycle in terms of theircharge and energy.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
7、 and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precautionstatements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:2D 150 Test Methods for AC Loss Characteristics and Per-mittivity (Dielectric Constant) of Solid Electrical In
8、sula-tionD 1711 Terminology Relating to Electrical InsulationD 1868 Test Method for Detection and Measurement ofPartial Discharge (Corona) Pulses in Evaluation of Insu-lation Systems32.2 IEEE Documents4IEEE 286 Recommended Practice for Measurement ofPower Factor and Power Factor Tip-up for RotatingM
9、achine Stator Coil InsulationIEEE 1434 Guide to the Measurement of Partial Dischargesin Rotating MachineryIEEE C57.113 Guide for PD Measurements in Liquid-FilledPower TransformersIEEE Standard C57.124 Recommended Practice for theDetection of PD and the Measurement ofApparent Chargein Dry-Type Transf
10、ormers2.3 AEIC Documents5AEIC T-24-380 Guide for Partial Discharge ProcedureAEIC CS5-87 Specifications for Thermoplastic andCrosslinked Polyethylene Insulated Shielded PowerCables Rated 5 through 35 kV, 9th Edition, 19873. Terminology3.1 Definitions:3.1.1 pseudoglow discharge, na type of partial dis
11、charge,which takes place within an expanded discharge channel and ischaracterized by pulses of relatively low magnitude and longrise time.3.1.1.1 DiscussionPseudoglow discharges occur within adiffused discharge channel, whose emitted glow fills the entireintervening gap or cavity space (1). The disc
12、harge rate behav-ior as a function of applied voltage is similar to that of the rapidrise time pulse (spark-type) discharges. The successivepseudoglow discharge pulses occur over the first quadrant ofeach half cycle and in some gases, notably helium, theirmagnitude is found to diminish to zero. At t
13、his point, atransition to a pulseless glow discharge can occur. Its occur-rence, which is manifest by distortion in the sinusoidal voltagewave, is rare. At discharge inception of a single cavity, the1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insu
14、lating Materials and are the direct responsibility ofSubcommittee D09.12 on Electrical Tests.Current edition approved May 1, 2007. Published July 2007. Originally approvedin 1975. Last previous edition approved in 2001 as D 3382 95 (2001)e1.2For referenced ASTM standards, visit the ASTM website, www
15、.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),445 Hoes Ln., P.O. Box 1331, P
16、iscataway, NJ 08854-1331, http:/www.ieee.org.5Available from The Association of Edison Illuminating Companies (AEIC),600 N. 18th St, Birmingham, AL 35291, www.aeic.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
17、 West Conshohocken, PA 19428-2959, United States.pattern of pseudoglow discharges consists of a single long risetime discharge current pulse in each half-cycle. It has becomecommon practice to refer to this particular type of pattern asthat of a glow discharge.Pseudoglow partial discharges, which oc
18、cur at low gaspressures, such as in insulating systems of electrical equipmentfor aerospace applications, have unduly long rise times and afrequency spectrum that falls bellow the bandwidth of conven-tional partial discharge pulse detectors (2). As a consequence,they cannot be detected by the partia
19、l discharge detectorsspecified inTest Method D 1868; however they can be detectedand measured by either Method A or B of Test MethodsD 3382.3.1.2 pulse discharge, na type of partial-discharge phe-nomenon characterized by a spark-type breakdown whichoccurs in a narrow constricted channel.3.1.2.1 Disc
20、ussionThe resultant detected pulse dischargehas a short rise time and its Fourier frequency spectrum mayextend as far as 1 GHz. Such a pulse discharge may be readilydetected by conventional pulse detectors, that are generallydesigned for partial-discharge measurements within the fre-quency band from
21、 30 kHz to several megahertz. (See alsoIEEE 1434, IEEE C57.113, IEEE C57.124, AEIC T-24-380,and AEIC CS5-87.)3.1.3 pulseless-glow discharge, nan uncommon type ofpartial discharge , whose existence is manifest not by the usualabrupt voltage fall discontinuities in the sinusoidal voltagewave at each d
22、ischarge epoch but rather by distortions in thewaveform.3.1.3.1 DiscussionIt is generally found that the pulselessglow region develops only when preceded by a pseudoglowdischarge in which the abrupt voltage collapse magnitudes ateach discharge have gradually diminished in the limit to zero.The natur
23、e of this pulseless glow region is not fully under-stood, but it is believed to consist of a very weakly ionized gasvolume. Further increases in the applied voltage can lead tomore complex partial discharge patterns, consisting of regionsof pseudoglow, pulseless and pulse type discharges (3) . Pulse
24、type partial discharge detectors of the type described in TestMethod D 1868 cannot be employed to detect pulseless glowdischarges.3.1.4 See (1) and (3) for more information on the previousdefinitions.3.1.5 For definitions of other terms pertaining to this stan-dard refer to Terminology D 1711.3.2 Sy
25、mbols:Symbols:3.2.1 Refer to Annex A1 for symbols for mathematicalterms used in this standard.4. Summary of Test Methods4.1 The dielectric characteristics of a specimen of solidinsulating material may be represented by a parallel combina-tion of capacitance and conductance. The values of capacitance
26、and conductance remain practically constant over the usefulrange of alternating voltage stress at a fixed frequency. If,however, the specimen contains gaseous inclusions (cavities),incremental increases in capacitance and conductance occur asthe voltage stress is raised above the value necessary to
27、initiatepartial discharges in the cavities. The energy loss in theincremental conductance is considered to be that dissipated bythe partial discharges.4.2 In Test Method A an initial measurement is made of thecapacitance and loss characteristic of the specimen at anapplied voltage below the discharg
28、e inception level. Thevoltage is then raised to the specified test value and a secondmeasurement made.The energy loss due to partial discharges iscalculated from the results of the two measurements.4.3 In Test Method B a special bridge circuit is balanced ata voltage below the discharge inception le
29、vel. The voltage isthen raised to the specified test value, but the bridge is notrebalanced.Any unbalanced voltage at the detector terminals isdisplayed in conjunction with the test voltage on an oscillo-scope. The oscilloscope pattern approximates a parallelogram,the area of which is a measure of t
30、he energy loss due to partialdischarges.5. Significance and Use5.1 These test methods are useful in research and qualitycontrol for evaluating insulating materials and systems sincethey provide for the measurement of charge transfer and energyloss due to partial discharges (4)(5)(6).5.2 Pulse measur
31、ements of partial discharges indicate themagnitude of individual discharges. However, if there arenumerous discharges per cycle it may be important to knowtheir charge sum, since this sum can be related to the totalvolume of internal gas spaces that are discharging, if it isassumed that the gas cavi
32、ties are simple capacitances in serieswith the capacitances of the solid dielectrics (7)(8).5.3 Internal (cavity-type) discharges are mainly of the pulse(spark-type) with rapid rise times or the pseudoglow-type withlong rise times, depending upon the discharge governingparameters existing within the
33、 cavity. If the rise times of thepseudoglow discharges are too long , they will evade detectionby pulse detectors as covered in Test Method D 1868. How-ever, both the pseudoglow discharges irrespective of the lengthof their rise time as well as pulseless glow can be readilymeasured either by Method
34、A or B of Test Methods D 3382.5.4 Pseudoglow discharges have been observed to occur inair, particularly when a partially conducting surface is in-volved. Such partially conducting surfaces may develop withpolymers that are exposed to partial discharges for sufficientlylong periods to accumulate acid
35、ic degradation products. Alsoin some applications, like turbogenerators, where a low mo-lecular weight gas such as hydrogen is used as a coolant,pseudoglow discharges may develop.6. Sources of Errors6.1 Surface DischargesAll discharges in the test speci-men are measured, whether on the surface or in
36、 internalcavities. If it is desired to measure only internal cavities, theother discharges must be avoided. In the case of an insulatedconductor with an outer electrode on the surface (such as acable or generator coil), the surface discharges at the end of thisouter electrode can be removed from the
37、 measurement with aclosely-spaced guard ring connected to ground. See Section 4of Test Methods D 150.6.2 Since tests will be made at ionizing voltage, all connec-tions making up the complete high-voltage circuit should beD3382072free of corona to avoid measurement interference. See Section5 of Test
38、Method D 1868.6.3 Other phenomena in addition to partial discharges mayproduce anomalous changes in insulation losses with changesin voltage stress. Such losses are a source of error in thesemethods, since they are indistinguishable from dischargelosses. However, these losses are often negligible in
39、 compari-son with partial discharge losses.6.4 Any temperature change in the specimen between thetimes at which the low-voltage and high-voltage measurementsare taken may cause a change in the normal losses and appearas changes in discharge energy, thus causing an error in testresults. This situatio
40、n can be recognized in Method B andcorrective action taken (see 11.3).6.5 Paint used to grade potential on the surface of someinsulation specimens (for example, generator stator coil)should not be included in the measurement, since the conduc-tance of such paints may change with voltage and affect t
41、heaccuracy of the method as a measure of discharge energy. It issometimes possible to exclude the painted surfaces from themeasuring circuit by the use of guarding or shielding tech-niques.7. Hazards7.1 Warning Lethal voltages may be present during thistest. It is essential that the test apparatus,
42、and all associatedequipment that may be electrically connected to it, be properlydesigned and installed for safe operation. Solidly ground allelectrically conductive parts that any person might come incontact with during the test. Provide means for use at thecompletion of any test to ground any part
43、s which: were at highvoltage during the test; may have acquired an induced chargeduring the test; may retain a charge even after disconnection ofthe voltage source. Thoroughly instruct all operators in theproper way to conduct tests safely. When making high voltagetests, particularly in compressed g
44、as or in oil, the energyreleased at breakdown may be suffcient to result in fire,explosion, or rupture of the test chamber. Design test equip-ment, test chambers, and test specimens so as to minimize thepossibility of such occurrences and to eliminate the possibilityof personal injury.7.2 Warning Oz
45、one is a physiologically hazardous gas atelevated concentrations. The exposure limits are set by gov-ernmental agencies and are usually based upon recommenda-tions made by the American Conference of GovernmentalIndustrial Hygienists.6Ozone is likely to be present whenevervoltages exist which are suf
46、fcient to cause partial, or complete,discharges in air or other atmospheres that contain oxygen.Ozone has a distinctive odor which is initially discernible atlow concentrations but sustained inhalation of ozone can causetemporary loss of sensitivity to the scent of ozone. Because ofthis it is import
47、ant to measure the concentration of ozone in theatmosphere, using commercially available monitoring devices,whenever the odor of ozone is persistently present or whenozone generating conditions continue. Use appropriate means,such as exhaust vents, to reduce ozone concentrations toacceptable levels
48、in working areas.TEST METHOD A8. Procedure8.1 Conventional circuits for the measurement ofalternating-voltage capacitance and loss characteristics of in-sulation can be used for this method. The transformer-ratioarmbridge shown in Fig. 1, or the Schering bridge shown inFig. X4.2 of Test Methods D 15
49、0 are well suited to thisapplication.8.2 Energize the test specimen at a low voltage, V1, belowthe discharge-inception voltage, and measure capacitance Cx1and dissipation factor tan d1. Raise the voltage to a specifiedtest level, V2, and repeat the measurements for Cx2and tan d2.Calculate the power loss, DP, in watts due to discharges atvoltage V2as follows:DP 5vV22Cx2tan d22 Cx1tan d1! (1)5 P22 P1V22/V12! (2)8.3 The increment of dissipation factor tan d2 tan d1,called delta tan delta, and written D tan d, is often used as anindex of discharge intensity.9. Precision and
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