Voltage, breakdown

Paschen s Rule and Breakdown Voltage. As pressure decreases to vacuum conditions, the breakdown voltage (BDV) first decreases, then increases, resulting in a minimum as shown in Figure 1. Table 3 gives BDV data for SF and other dielectrics. For optimum utiUty of a dielectric, a... 

ASTM D149, Test Methodsfor Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies, Vol. 8.01, ASTM, Philadelphia, Pa., 1987. 

Fig. 7. Circuit symbol and current, /, voltage, U, characteristic of a p—n junction diode where = breakdown voltage(32).

Fig. 1. Currents are d-c (dashed lines and empty symbols) and peak a-c (soHd lines and soHd symbols) breakdown voltage vs gas pressure in nickel for the various gaps, noted by values x 10 m on the curves (16). To convert Pa to torr, divide by 133.3.

FIG. 24-14 Dissolved-oxygen electrodes a) polarographic (impress breakdown voltage for oxygen measure current) (h) voltametric (measure electromotive force). 

PBDs were not observed for layers less than 23 /rm thick and the PBD film potential threshold varied from 4-5 kV at 23/rm to 11 kVatl75/rm [228]. A later study, possibly using a less valid method for measuring film potential, reported smaller threshold values [ 29 ]. The later study concluded that if film breakdown voltage is less than about 4 kV at 20/rm and about 8 kV at 200/rm, PBDs cannot be produced. This is shown schematically in Figure 2-6.5. 

Increase breakdown voltage of wall by increasing thickness and/or changing material of construction. 

There is no available evidence that PBDs occur in FIBC operations and therefore no demonstrated need for thin walled Type B containers designed with a breakdown voltage of 4 kV or less [lOj. However, since Type B containers are commercially available and in principle may offer slightly less risk, they might be considered where thin walls will not have a detrimental effect on product quality (6-7.1.1). 

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