1、DEUTSCHE NORMEN July 1: UDC 621.315.615 : 62O-I : 621.317.335.3 : 621.317-374 I x Testing of Insulating Materials Determination of Dielectric Properties Measuring Cells for Liquids for Frequencies up to 100 MIIz UIIy I 53483 Sheet 3 Prfung von Isolierstoffen; Mezellen fr Flssigkeiten fr Frequenzen b
2、is 100 MIIz Bestimmung der dielektrischen Eigenschaften, For connection with IEC Publication 250-1966, see Explanations. This Standard has been com iled as a result of co-operation between the German Standards Association (DNA) and the gociety of German Electrical Engineers (VDE) represented on the
3、joint DNE Committee l,Dieleotric measurement“ and it agrees in subject matter with VDE Specification ME O303 Part 4, jointly with DIN 53483 Sheet I and Sheet 2. The following also belong to this Standard: DIN 53483 Sheet I DIN 53483 Sheet 2 Further Sheets are in course of preparation. Testing of ins
4、ulating materials, determination of dielectric properties; definition, general -; testing at standard frequencies of 50 HE, I KHI, 1 MFz Dimensions in mm Contents Page I. Requirements 1 2. Cleaning 2 3. Evaluation of the results - . . 2 I. Reouirements To guarantee satisfactorg measurements, measuri
5、ng cells for the determination of the relative permittivity and dielectric loss factor of liquid insulating materials and of fusible insulating compounds must satisfy the requirements set out below. The measuring cells must be easy to use and must be capable of being cleaned easily and quickly. The
6、measuring cells must be constructed in such a manner that they permit accurate temperature- holding, and the temperature of both electrodes must be capable of being measured. The measuring cells must be constructed of materials capable of withstanding the temperatures at which the measurements are m
7、ade without upsetting the location of the electrodes. The measuring cells and the electrode surfaces must consist of materials which neither undergo attack by the insulating material being tested, and by any impurities or ageing products to which it gives rise, nor experience any change due to the i
8、nsulating material being tested. Furthermore, the materials used must not have the proper I? o t e . gold, 21atinum or rhodium on the surfaces in contact with the liquid under test. Often, too, aluminium and duralumin have proved satisfactory. For insulating tho electrodes, quarts glasses or borosil
9、icate glasses are recommended. of absorbing the insulati material being tested. Suitable materials ara stainless ate%, also metals coated with elesroplated nickel, chromiumI The parts of the measuring cells which insulate the electrodes from each other shall not be capable of being wetted by the liq
10、uid under test. If necessary, suitable liquid outlets shall be provided. &e measuring cells and their electrical connections shall be designed in such a manner as to sllow effective electrical shielding. Phe measuring cell electrodes shall be separated from each other by adequately long creepage tif
11、ferences and shall not have any sharp edges within the volume involved in the test. leamring cells for use at frequencies above I MtIz shall preferably be designed to plug onto the :apacitance-measuring device direct, and shall have capacities f 50 pF in the filled condition. N o t e 1 : Measuring c
12、ells according to Fig. 2 are particularly suitable for high frequencies. N o t e it may be necessary to adopt a measuring cell of the smallest possible size. 2 i If only a small amount of the liquid to be tested is available for fillin8 the measUrin& Cell, Continued on pages 2 and 3 Explanations on
13、page 3 DIN 53483 B1.3 engl.Preirnr Ieinvorkouf der NormblBttw durch Beuth-Vertrieb GmbH, Berlin 30 und Kln Page 2 DIN 53483 Sheet 3 Eies,of-exectioo_oi-ea8r6-cell8 Figs. I to 3 show measuring cells which have proved satisfactory in practical use. Measuring cella as shown in figa. I and 3 are also su
14、itable for determining the volume resistance of the insulating liquid. For measurements on fusible insulating compounds, a measuring cell as shown in Fig. 3 can be used. Thia representa a variant of the circular disc electrode with guard ring. The specimen layer is made to slope downwards towards th
15、e middle to reduce the formation of voids during solidification of the compound. 2. Cleaninn the measurinn cells) The measuring cells shall be cleaned with a solvent, or with different solvents in a fixed sequence. The solvents used must be chemically pure. If the solvents used are incapable of remo
16、ving all traces of the insulating liquid, the use of a mild cleansing agent and water is indicated. If two or more solvents are used in succession, the one used last should be an analytical grade gasoline with a boiling point below 100 OC, or a solvent which is chemically similar to the insulating l
17、iquid under test, and the use of which yields the right values for a liquid of known dielectric properties. The measuring cells shall be cleaned in the dismantled condition in a Soxleth apparatus, or by repeated washing in fresh solvent, and then dried for half an hour at about 110 OC in a hot cabin
18、et. After the measuring cell has been re-assembled it is advisable to rinse it out, prior to performing the testing, with some of the liquid which is due to be tested and which has already undergone any necessary pretreatment. It is important to note that during the entire cleaning process none of t
19、he effective electrode surfaces ahould be touched with the hands. PI o t e : When makin sucFeasive measurement8 on liquids.of like kin8 it is sufficient to clean the measuring cell by merely wiyi it with a suitable type of absorbent paper %ch does not leave any fibras behind. 3. Evaluation of the re
20、sults The relative permittivity gr of the liquid under testing is found from the numerical equation cx - r=+T If a high standard of accuracy is called for in the determination of the relative permittivity of the liquid under testing, the electrode constant C shall be checked before- hand by means of
21、 a chibration liquid (e.g. benzole) of known relative permittivityz) . The electrode constant Cc in pF is found from the numerical equation n - O cc = Where : Ox Cg Cn en 1 When workinn with solvents it is important that the is the capacitance of the meaning cell, filled with the liquid under testin
22、g in pF is the capacitance of the measuring cell in air, in pP ia the capacitance of the measuring cell, filled with the calibrating liquid, in pF is the relative permittivity of the calibrating liquid relevant regulations should be observed with regard to any necessary health and fire-prevention pr
23、e- cautions. =) For information on the relative permittivity of different li uids see for exam ie Kohlrausch “Praktische %hysik“ (Practical khysics) Vol. 3 (1968) * r- 690-1 nsulathg and electrode Thernometer L- $50 _I Figure 1. Measuring cell with guard ring Hole for thermometer Metal plate . f to
24、measuring device -t 1 or 2 mm g6P thermome t er r to voltage source Figure 2. Measuring cell with plane electrodes, without guard ring electrode (see also Note 1 in Section 1) Ceramic insulating and locating rings ri 1 ct :ion Specimen Hole for thermometer Potential connection “ / Energized electrod
25、e Figure 3. Meaauring cell with guard ring for fusible insulating compounds Explanations In order to keep abreast of developments in test methods and international itandardization, the content of what was previously DIN 53483, October 1955 issue and DIN 53483 Supplementary Sheet 2, October 1955 issu
26、e ir now being split up into DIB 53483 Sheet 1 to Sheet 3. The issue of further standards in place of DIN 53483 Supplementary Sheet 1, October 195SXissue, is envisage d. Thia Standard agrees in content with Seotion 4.2 of IEC Publication 250-1968 “Recommended methods for the determination of electri
27、cal insulating materils at power, audio and radio frequenciee including metre wavelength118). In contrast with the IEC Publication referred to, the cylindrical measuring cell without guard ring indicated in that document (in Fig. 3) haa not been adopted. Instead, the measuring cell for fusible compo
28、unds dealt with in DIN 53483 Supplementary Cheat 2 (October 1955 issue) has been retained. Instead of meacruring cells without guard ring, any of the measuring cells with guard ring indicated in the prtsent standard can be used, the guard ring being connected to the outer electrode. In auch cases, a fresh determination of the electrode constant Cc (see Section 3) is recommended. When using meaeuring Cells without guard ring in particular, it is important to maintain a constant filling height, ) IEC: International Electrottcnical Commiseion
