earticle

영어

The prevention measures on fires caused by heating cables which are widely used in factories are studied. The insulation degradation leads to arc discharges, which can cause electrical fires. It is possible to prevent fires by the early detection of arc signal, since the arc discharges progress very slowly for a long time. By considering the characteristics of arc discharges, fire alarm system is designed and fabricated, which is composed of a circuit breaker, an AFCI, an arc module and an automatic fire alarm-report module. The arc module can identify an arc pulse and a noise through a high-pass filter with the low cut-off frequency of 16 kHz, a waveform shaping circuit and a microprocessor. Also, an algorithm was designed to discriminate the arc signal only in the presence of noise, comparing with the number of pulse counts per 100 ms. Field experiments were carried out in a 80 meters-long heating cable using an arc generator specified in UL1699. The results showed that the fire alarm system could detect the arc signal over 99 % and trip the circuit breaker in a few seconds.