Electrical tests dissipation factor

BS 7663, 1993. Methods of test for determination of permittivity and dissipation factor of electrical insulating material in sheet or tubular form. 

Dielectric test methods are used to measure the cure of epoxy adhesives between two conducting electrodes. This method is especially appropriate for metal-to-metal joints because the substrates themselves can be used as the electrode. The adhesive is treated as a capacitor during the test. Its response (dielectric constant, dissipation factor, etc.) over a range of electrical frequencies is measured as a function of curing time. 

Constant, dissipation factor dielectric strength. A literature search indicated that little work of this nature has been done with expl materials. Further, such electrical measurements can be used as supplementary criteria for evaluating the purity, homogeneity and, with the exception of the dielectric strength determination, as possible nondestructive tests of expls. Hence the data listed in the following table were deed at Pic Arsn (Ref 2) for the common readily avail expls which are believed to be of interest in research... 

ASTM D 1673-79 (1989) Standard Test Methods for Relative Permittivity and Dissipation Factor of Expcmded Cellular Plastics Used for Electrical Insulation, 5 pp (Conun D-9)... 

Table V Indicates the good retention of electrical properties exhibited by the 40% glass-filled PPS at temperatures up to 147°C. In addition, exposure of test specimens to 50 per cent relative humidity for 5 days did not cause any appreciable change In either dielectric constant or dissipation factor. Thus, environmental factors do not have much effect upon the electrical behavior of polyphenylene sulfide resins.

Electrical Properties. The electrical properties of silicone gels are essentially the same as those of most clean, unfilled silicone elastomers and fluids. Typical values for dielectric constant and dissipation factor when tested at 25°C and 100 Hz are 2.7 to 2.9 and 0.001 to 0.002 respectively. Volume resistivity values, usually, fall in the 10 ohm- centimeter range. 

Dissipation factor (also known as "power factor" or "loss tangent") in electrical tests. Mechanical loss tangent under the uniaxial tension mode of deformation. 

The main electrical properties related to organic materials are volume resistivity (for both conductive and nonconductive adhesives) and dielectric constant and dissipation factor (for insulative materials). Other electrical tests for conductive materials that are more application specific are electrical stability, current-carrying capacity, and interconnect resistance. 

ASTM D150 Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation includes the determination of relative permittivity, dissipation factor, loss index, power factor, phase angle, and loss angle through specimens of solid electrical insulating materials when the standards used are lumped impedances. The frequency range that can be covered extends from less than 1 Hz to several hundred megahertz. 

Standard testing of electrical properties of plastics includes dielectric strength, permittivity, dissipation factor, smface and volume resistivity, and arc resistance. Dielectric strength is the maximmn voltage required for breakdown and is determined by one of three techniques short-time, slow-rate or slow-rise, and step-by-step. The two last techniques use data from the short-time test to... 

Test Methods for a-c Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulating Materials Test Method for Dissipation Factor and Permittivity Parallel with Laminations of Laminated Sheet and Plate Insulating Materials Test Methods for Relative Permittivity (Dielectric Constant) and Dissipation Factor of Polyethylene hy Liquid Displacement Procedure... 

The relationship between the half-widths of the mechanical and electrical absorption peaks (the temperature range over which the value of the dissipation factor drops to half of the maximum) is shown in Figure 43. The mechanical tests give narrower absorption peaks than the electrical tests, but a fair correlation exists between them. The width of the peak is less dependent upon frequency than its magnitude, and a true difference between mechanical and electrical properties is probably indicated. 

Most thermoplastic materials are inherently nonconductive and work well as electrical insulators. There are numerous test methods for evaluating the insulating properties thermoplastics, including dielectric strength, arc resistance, surface resistivity, volume resistivity, and dissipation factor. 

One of the main reasons why plastics have become so widely used in electronics and electrical applications is that they are good dielectric materials with readily controllable electrical properties. However, the fact that plastics are good insulators does not mean that they are inert in an electrical field and the intrinsic properties of a material can usually be related to performance under specific test conditions. The electrical properties that have to be considered when selecting a material are the dielectric constant, the volume resistivity, surface resistivity, dissipation, power and loss factors, arc resistance and dielectric strength. When selecting a plastic for a specific application the variation of these properties with changes in the likely service environment has to be taken into account since many of them are temperature, frequency, voltage and environmentally variable. 

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