1、DEUTSCHE NORMEN March 19 UD0 621.315.61 : 620.1 : 621.317-335.3 : 621.317.374 Tastinu of Insulatinn Materials I Determi Bestimmung der dielektrischen Eigenschaften, Prfung bei den festgelegten Frequenzen 50 Ha, I Ha, 1 MBs For connection with IEC Publication 250-1968, see Explanations. This Standard
2、 has been compiled as a remit of co-operation between the German Standards Aseocia- tion (DNA) and the Society of German Electrical Bngineers (DE) represented on the doint DNUm Zommittee “Dielectric measurements“ and it agrees in subject matter with VDE Specification WDE 0303 Part 4, jointly with DI
3、N 53483 Sheet 1 and Sheet 3. me followlng also belong to this Standard: DIN 53483 Sheet 1 DIN 53483 Sheet 3 Further Sheets are in course of preparation. Testing of insulating materials, determination of dielectric properties; definitions, general information -; measuring cells at frequencies up to I
4、o0 HEC Contents Page I. Purpose and application 1 2. Apparatus . 1 3. lest procedure 4 4. Evaluation 4 1. purr ose and amdication Phe testing of insulating materials for compliance with given dielectric properties (e.g. type ratings) according to this Standard can be performed at one or more standar
5、d frequencies. Such oeasurements also quickly yield a qualitative picture of the properties of an insulating material instead of a continuous determination of its frequency dependence. When performed with test 5quipment specifically built for these frequencies the test benefits from the fact that th
6、e apparatus is optimally matched to its purpose and therefore the results obtained in this way for the teat point concerned may be more accurate than those obtained with wide-band apparatus. N o t e : The testing of components can be carried out with the samit test equipment at the same frequencies.
7、 iihen testing, the provisione of this Standard should be applied a8 appropriate. Phe standard frequencies used are 50 EIz, I kIft and I HEZ. ?. Apparatus he testing requires the following items: 2.1. h a.c. s u p p 1 y i n g he generator must be adequately decoupled from the measuring circuit so th
8、at no voltage or rrequency variations will be brought about by the balancing of the measuring circuit. The output roltage shall be variable. The measuring frequency shall not variate from the desired value by nore than ?.2. A d e t e c t o r )r in conjunction with an amplifier to increase its sensit
9、ivity. Cxanples of detectors are a telephone plue amplifier or frepency converter, electronic volt- ieters, and electronic null indicators with optical indication. ?.3. A 1.01 C, 2 0.5 pF and the dielectric loss factor tan 4 at g e n e r a t o r the frequency needed for measuring purposes. 5 %. The
10、harmonic content shall not be higher than 1 %. for balancing the measuring device. !be detector may be used on its own m e a s u r i n g d e v i c e allowing the to be stated at 1 ast to I tancomino1 value A for 2.4. An such that the specimen lies between the electrodes in an electric field characte
11、rized by maximum homogeneity or defined in some other WW. 2.4.1. For s o 1 i d are preferred. If the insulating material is supplied in the form of tubes, these may also be used. As a guide to the size of the electrode area needed it is deemed that the capacitance cx of the Hence, the two different
12、measuring arrangements which are possible for solid materials are: a) Electrodes applied directly to the surface of the specimen (preferably adherent electrodes), b) Immersion capacitors. 2.4.1.1. Electrodes applied directly to the surface of the specimen. !be electrodes used are either circular dis
13、c electrodes (see Fig.?) or cylindrical electrodes (see Fig. 2) with guard ring. The width of the guard gap shall be as small as possible, and in any case shall not exceed I mm. The width of the guard ring shall be at least equal to twice the electrode separation (thickness of specimen). Recommended
14、 dimensions for electrodes according to Fig. I are listed in Table 1. The electric field between the electrodes e 1 e c t r o d e a r r a n g e m e n t i n s u 1 a t i n g m a t e r i a 1 s , specimens in sheet form electrode arrangement should not be smaller than 20 pF. to voltage source ergized el
15、ectro 5 Guard ring 4 1 Lard Jing is virtually homogeneous when the width of the guard gap is small in relation to the electrode Separation, when the guard ring is of adequate width and when the guarded electrode and the guard ring guarded Specimen Specimen nesses rieases over 1 rnw ,q to 1 mm thick-
16、 thick- Cd cmt have approximately the same potential to earth. A guard ring can be dispensed with if the electrode separation is smaller than 1 mm. If a guard ring cannot be used, it will normally be necessary to calculate the correction for the edge effect. Formulae for various electrode arrangemen
17、ts are given in Table 2. krangement b) or e) in Table 2 yields the simplest method of calculating for edge effect. Methods c) or f) should be used if the electroes do not extend to the edge of the specimen. In this case the condition that the thickness of the electrode should be very small compared
18、with the specimen thickness need only be satisfied for the smaller of the two electrodes. Calculation of the relative permittivity from the measured capacitance of the electrode arrangement and its geometrical dimensions assumes, inter alia, that the whole of the effective area of the electrodes bea
19、rs closely, i-e. without any gap, on the surface of the specimen. “his condition is best fulfilled by directly applying a thin electrically conductive coating to the surface of the specimen (adherent electrodes). Various methods of constituting such electrodes are indicated below. When the choice of
20、 method is being made it is important to ensure that the specimen is not permanently changed in any manner whatsoever or that, if changes do occur, they can be reversed. me following types of electrode are commonly used: a) Electrodes consisting of colloidal suspensions of silver or in the form of v
21、arnish-like liquids containing finely divided silver as the electrically conductive constituent (known as conductive silver preparations). b) Electrodes consisting of stabilized, colloidal, aqueous suspensions of graphite. N o t e s r e a) a n d b): Tne tj2es of electrode mentioned above are not sui
22、table for porous insulating materials. Thorough drying following application is important. Both types of electrode are permeable to moisture and are usable at temperatures up to about 100 OC - and in some cases up to 200 OC. In the case of the type a) electrode care must be taken to enaure that the
23、insulating material is not attacked by the solvent. Electrode type b) ia suitable only for measurements at 50 Ez and 1 kHz. C) Metal electrodes applied by cathodic evaporation or evaporation in high vacuu. These can be used wherever the resultant Stresses neither permanently change nor damage the in
24、sulating material. d1 .iidth rnm mm elect rode I device 5 20 80 u 242 192 495 1 10 78,l 99#9 N o t e : lne meiisurinr; ilrea is the area bounded by tae nid-line of the guard gap (holds coo3 only for Column 1 of lable 1). dyecimen (tube) figure 2. (tylindrical electrode with guard ring for tubular sp
25、ecimens Measuring area - F - da (1 + g) DIN 53483 Sheet 2 Page 3 R o t e : that the specimens o(u1 be suitably treated even after the adherent electrode hae been applied. a suitable In thicknesses up to about 5pi the metal film ia adequitely permeablb to moisture, so Electrodes of types a) to o) are
26、 best applied to the specimens by sprayin mask being used during this process to produce a guard ring arrangement. 8; is important that the edges of such electrodem shall be sharply defined and clean. d) Fired-on electrodes produced by firing a metal salt on to the surface of the insulating material
27、. “hese electrodes are Frimarily suitable for glass and ceramic insulating materiaie. No t e t Metal electrodes consis ing of indium amalgam or an indium-gallium eutectic have proved suitable as barrier-layer-free contact media for ceramic insulating materiale. Indium-gallium films retain this prope
28、rty even ai underlays to fired-on silver electrodes according to d) above. If electrode types a) to d) above cannot be used, the following kinds may be adopted: e) Electrodes consisting of thin foils of tin, lead or an alloy of these, or of aluminium, silver or gold which are rubbed down onto the sp
29、ecimen after application of a trace of silicone grease or a similar low-loss adhesive. As take-off electrodes for the adherent electrodes according to a) to e) above, metal plates are used for plane specimens; for tubular specimens, metal strip ie suitable. The diameter and width of the take-off ele
30、ctrodes shall be amaller than those of the adherent electrodes. If a guard ring is not used, then - owing to the fact that in such cases calculation of the edge effect generally demands very thin electrodes - the take-off electrodes ueed should be about 10 mm smaller in diameter and width than the a
31、dherent electrodes used (ses Fig. 4). f) Ordinary, sharp-edged contact electrodes without guard ring or contact electrodes with guard ring (e.g. precision capacitors) which muet be ground to bear perfectly flat one on the other. N o t e 1 : When using electrodes of this kind it ie very important to
32、ensure that the electrodes make close contact with the specimen surface. This can be achieved by using a suitable silicone oil as an adhesive. N O t e The application of edge effect correction in Table 2 for electrodes without guard ring generally re uires that the thickness of the electrodes at the
33、 edge should be small compared with the pe cimeri thi%ness. 2.4.1.2. Immersion capacitor The immersion method largely avoids the errors in determining the relative permittivity, which arise from inexact knowledge of specimen thickness, provided that the meaaurement is made in a liquid whose permitti
34、vity is nearly equal to that of the specimen. This measuring method depends on determining the differencebc of the measured capacitances C, with the space 2 I to measuring device (measuring lead) between the electrodes of the precision capacitor entirely and exclusively occupied by the immersion liq
35、uid, and C;! with the immersion liquid partly displaced from Shielding cap between the elect-rodes- by the specimen. The observed difference in capacitance can be either positive or negative, depending on whether E, is larger or smaller than Erf, and reduces as Iu Specimen proviso-that they shall ne
36、ither ckange the specimen itself nor the materiale used for the electrode arrangement. Silicone *nergi I / I oils have proved ven suitable for this o t e 1: For information on the relative permittivity of various liquids see. for example, Kohlrausch “Praktische Physik“ (Practical Physics) Vol. 3 (19
37、68). urvose. I dl 9 to voltage source R- N 0 t e immersion capacitor the immersion liquids accordina to DIN 53483 Sheet 3 are to be tested 2: Before they are used in the Figure 3. Disc electrode with guard ring for sheet specimens (example of execution) at the relevant msu-ing f e uencies and temper
38、atures. Two methods are appfiicabiei a: I The determinatin of Em (or tanb,) by using a single immersion liquid tr. (or tan 6 1. In this case the characterfetics of the capacitor (Co and 8) should be substituted in the appropriate formulae of Table 3, together with the average thickness of the specim
39、en. If it is not pos ible to meet the condition k, - ErflZ 0.1 it will be necessary for which is the capacitance of the empty configuration, to be replaced by a self- capacitance value which must be determined for the capacitor by immersion liquids 1. to maeuring device (meampring lead) ke-off elect
40、rode using a number of r. Wrstlin: “Messungen der dielektrischen Eigenschaften tage ron Hochpolymeren rit einer Iniersionimethode“ (Measure- nents of the dielectric properties of high polymero by means of nn imersion method), Kolloid-Zeitichrift, fol. 213 (1966)s pp. 79-88. Figure 4. Example of an e
41、lectrode arrangement with take-off electrode but without guard ring (example of execution) zage 4 DIN 53483 Sheet 2 h) By using two immersion liquids, which should preferably be selected so that Er C?rf2 , both the specimen thickness and also the capacitor characteristics can be compfkta eliminated
42、from the equations. Formulae for evaluating the measurement results are given in Table 3. The immersion method is particularly suitable for determining the relative permittivity of foamed materials and of soft or elastic substancea. Por the first-mentioned case, air is used as the immersion medium.
43、Plane or cylindrical electrode arrangements can be used for the measurement. A proven type of measuring cell for plane specimens is shown in Fi . 5. For use with this measuring cell, two specimens, which should be as nearly equal in fhickness as possible, are t should be noted that, in this case, wh
44、en calculating the empty capacitance Co = - twice the measuring arec A of the measuring electrode should be used. 8 2.4.2. Liquid insulating materials and fusible to measuring device (measuring lead) insulating materials are tested in suitable measuring cells (see DIN 53483 Sheet 3). 2ra,oeoices_oor
45、_meas-e-i fsEm2Zz a) Device for measuring specimen thickness h within an error limit of 0.02 h + 0.005 mm. Bo t e : It must be appreciated that ome of the materials standards contain particulars specially relating to the determination of specimen thickness (e.g. for plastics film in DIN 53370). b) D
46、evice for measuri the electrode dimensions with an error limit of 0.5% of the electrode dimensions. N o t e : The accuracy of the dielectric data obtained depends on the accuracy with which specimen thickness and electrode dimensions are determined. 3. lest procedure 3.1. The specimens are treated a
47、ccording to the particulars in the relevant standards and VDE specifications for the insulating material. 3.2. If treatment of the specimens to determine the effect of moisture is to be undertaken, the thickness h of specimens consisting of solid insulating materials should be determined first to wi
48、thin + (0.02 h + 0.005 mm), and the adherent electrode then applied. No t e 1 : If it is intended to determine the temperature dependence of the dielectric properties. the measurements are to be carried out on the specimens in a thermostatically controlled Chamber or by using temperature-controlled
49、Contact electrodes. Another possible method is to use the hersion N o t e 2: When so stipulated, it is convenient to measure the volume resistance of the specimen according to DIN 53482 (VDE 0303 Part 3) at each temperature immediately after the relative permittivity and the dielectric loss factor have been determined. capacltor. Figure 5. Immersion capacitor for plane specimens (Schematic) 4.1.1. Using measurements obtained with adherent !The relative pennittivity Er is usually determined from the measured capacitance ring, the measured capacitance Cx also con
