Back Corona

In working ESPs, a portion of the applied potential is dropped across the resistive layer of the collected dust. As the dust layer thickens the resistance, hence voltage drop, across the layer increases. If the dust resistivity is high (p > 1010 Q-cm), eventually the field becomes great enough to cause electrical breakdown of gas within the dust layer, generating a back corona. Electrons are ripped from the gas, and the resulting positive ions flow into the inter-electrode space, where they attach to negatively charged particles. The diminished net charge of the particulates leads to greatly diminished collection efficiency; re-entrainment also occurs. A back corona occurs with an electrical field strength across the dust layer (resistance of layer times current) of 8-12 kV cm"1.

A back corona can be visually observed as a glow on the collection surface. It is also characterized by an increase in corona onset voltage followed by an increase in current for a given applied voltage as compared with a correctly functioning system (Figure 5). The dust layer acts as a resistive-capacitative element in having a lag time before discharge. Both intermittent and pulse energization take advantage of this lag time to allow the application of high voltage without the occurrence of back corona.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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