Partial discharge measurements

So, partial discharge measurements have become a well-established method for type and routine testing as a non-destructive material test and quality control [23], [26], [53]. Apart from optical and acoustical detection methods of partial discharges, the high frequency detection and measuring method preferably covers a wide range of applications. It will be considered in more detail in the following. 

The basic principle of partial discharge measurement may be explained with a rather simple model (Fig. 8.4). A coaxial cable with an intact dielectric... 

Part 3 Test methods for partial discharge measurement on lengths of extruded power cable. 

Method for measuring partial discharges in instrument transformers 11.322/1990 BS 6184/1992 -... 

Fig. 5.7. Stability analysis of a process control loop for the reactive magnetron sputtering of high-index metal oxides. The control of discharge power to stabilize the oxygen partial pressure set point is modeled within the framework of the Berg model. A cycle time of 100 ms and process uncertainties for discharge current and oxygen partial pressure measurements are assumed, (from [71])...

Partial discharge (PD) measurements applied to components or apparatus subject to electrical stresses, e.g. components according to encapsulation - m or complying with increased safety - e - ... 

Hypothesizing The density of a sample of electrolyte from a lead-acid battery is measured and found to be 1.09 g/mL. Do you think this density indicates a fully charged battery, partially discharged battery, or a dead battery Give a reason for your choice. 

Another version of optical multichannel analyzers is based on the vidicon principle. The diode array is irradiated on one side by the image to be detected (Fig. 4.92) and the absorbed photons produce electron-hole pairs. The diodes are reverse biased and the holes that diffuse into the p-zone partially discharge the p-n junction. If the other side of the array is scanned with a focused electron beam (20-p.m diameter), the electrons recharge the anodes until they have nearly cathode potential. This recharging, which just compensates for the discharge by the incident photons, can be determined as a current pulse in the external circuit and is measured as the video signal. 

Figure 2. Test cell for measuring the partial-discharge threshold voltage.

Haidara and Denat (1991) investigated the onset of partial discharge pulses in a test cell with 50 D impedance consisting of a fine tip as cathode and a plane metal disk as anode. By comparing the threshold voltage in the vapor and in the liquid they were able to estimate values for a in the liquid phase as a function of applied field. Their data and for comparison the ionization rates reported for silicon are included in Figure 1. A crude estimation of a in liquid n-hexane obtained from time lag to breakdown measurements with thin liquid layers by Arii et al. (1979) is also included. 

Elimination of Heavy Metals. Until recent times, the addition of mercury metal to the anode has been widely used to perform several functions in the mix as well as on the collector. These are listed in Table 10.5. However, the industry has reduced or eliminated heavy metals from the battery. The absence of mercury from the anode can lead to reduced service, increased sensitivity to mechanical shock, and increased gassing on initial storage and after partial discharge. It has been necessary to find substitutes for each of the functions of mercury. Such measures have been described in related sections of this chapter. In general. 

Method for Detection and Measurement of Partial Discharge (Corona) Pulses in Evaluation of Insulation Systems Methods for Measurement of Enei and Integrated Charge Transfer Due to Partial Discharges (Corona) Using Bridge Techniques... 

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