Identification of thermal fault states in cable insulation sheaths based on gas sensor arrays

As one of the most commonly used electrical equipment materials, low and medium voltage cables inevitably suffer from overheating faults and cause fires during operation due to harsh working environments and overloaded operation. However, there is a lack of economical and reliable cable fire detection methods. In the early stage of fire, gas volatiles are often produced earlier than visible smoke. Therefore, this paper focuses on gas volatiles in early cable fires. Taking polyvinyl chloride (PVC), a commonly used outer sheath material for low-and medium-voltage cables, as the research object, gas chromatography-mass spectrometry was used to study its gaseous volatile products and their temperature characteristics when overheating, and it was found that di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) produced at low temperatures had positive temperature characteristics under the area-normalized quantification method. Based on these two main gas products and the broad-spectrum characteristics of the gas sensor, the gas sensor array was selected and constructed, and the gas response data of PVC cables under six temperature conditions were designed. The samples were classified into three states, namely, normal, early warning, and alarm, according to the sample state, and the Extra Trees algorithm was used to categorize the sample state, and the recognition accuracy rate reached 97%. During the whole experiment, the smoke alarm did not send out any alarm signal.