| 摘要 |
PROBLEM TO BE SOLVED: To break a circuit quickly, by separating a positive themistor away from a lead wire by a spring force of a coil-shaped spring when solder has been melted by the positive thermistor heating up itself in the event that an overvoltage or an overcurrent is applied to the positive thermistor. SOLUTION: A nickel-placed and a tin-placed electrodes are formed on both side faces of a positive thermistor (for example, 7ϕ×2.5tmm, Curie temperature: 90 deg.C, a resistant value: 12Ω), and lead wires 2, 3, of 0.5ϕfor example, are soldered to the electrodes with tin-lead eutectic solder. Then the lead wire 2 is soldered to a substrate 6 while a fixed end of a coil-shaped spring 5 is soldered to the substrate 6. Then the other end of the coil-shaped spring is hooked on and soldered to the lead wire 3. In this state, if a current, of 600V 40A, 600V 7A, or 600V 2.2A for example, is made to flow through the lead wires and the coil-shaped spring 5, the current flows through the positive thermistor, which heats up itself until it exceeds 183 deg.C, the melting point of solder, and the lead wire 3 is separated away from the thermistor, whereby a circuit is broken.
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