Electrical currents and breakdown voltages as a diagnostic tool for fires

• Two types of electrical measurements have been investigated in order to perform diagnostics of the fire dynamics in the ISO 5660 cone calorimeter. The rationale of the study is to take advantage of the pilot ignition electrodes that are already in place and use these to collect additional information such as emission of pyrolysis gases and time to ignition. The first part of the project was a refinement of the method for measuring the so called ion current, which has already been investigated in a pilot study. It was found that thorough shielding and grounding gives an excellent signal to noise ratio. An expression for the correlation between measured current and conductivity was also developed and validated experimentally. The second part of the project consisted of measuring the breakdown voltage, that is the voltage when dielectric failure occurs. It was found that this method was more sensitive to the fire dynamics before ignition, such as pyrolysis, but that the response to ignition was more ambiguous for the breakdown voltage than for the ion current.

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ref (subject category)

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