| 摘要 |
<p>Circuit breaker or protective switch device, consists of a self-restoring, current limiting element (I), connected in series with a meltable fuse. When the electric current actuates element (I), the fuse is driven into its switch-off or melting zone and interrupts the current. The pref. device uses an element (I) consisting of a metal which is liq. at room temp. or has a low m.pt. and is readily volatile, so that when a short circuit occurs, resistance heating converts the metal into vapour with a high electric resistance, thereby limiting the current; on cooling, the metal is restored to its state of good electric conductivity. When a low impedance short circuit current occurs, element (I) actuates the fuse. Element (I) pref. consists of Hg, Na, K, or a mixt. of Na + K, and is connected in series with a fuse (2) made e.g. of conventional wire.</p> |
