• Fire Science and Engineering
• /
• v.8 no.1
• /
• pp.3-8
• /
• 1994

A new test system was established to measure the flame extinguishing concentration of Halon alternatives. The main characteristic of this system is to use the solid paraffin with a wick instead of liquid fuel, such as n-Heptane. Our results showed that the extinguishing concentration of compounds was lower than that of other existing data, but the trend was consistent with others. The flame extinguishing concentration of all tested compounds were not almost effected by gas flow velocity. The system produces good reliable data with a minimum error for measuring the flame extinguishing concentration. Therefore our new system can be utilized as a standard equipment to evaluate Halon alternatives.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.10
• /
• pp.630-635
• /
• 2015

A vacuum Interrupter (VI), a core part that composes the breaking part of medium-voltage vacuum circuit breaker (VCB), has the excellent insulation performance and arc-extinguishing capability. $SF_6$ gas had been used for the external insulation of VIs since the dielectric strength of $SF_6$ gas is superior to that of other insulation gases. However, because of environmental problems related with global warming, a solid-insulated technology was recently researched. The functionally graded material (FGM), as changing spatially the distribution of the relative permittivity inside an insulator, can reduce the electric field stress at the specific region. Especially, the external insulation performance of the VI with the molded FGM insulator is greatly improved as compared with that of the existing VI or the VI with a new external shield. In this paper, the effectiveness of this FGM insulator is verified by the numerical simulation.