| 摘要 |
An insulating member of metal oxide varistor material separates the two conductive parts of a hermetically sealed enclosure to which the electrodes of the switch are attached. The metallic oxide varistor material has a voltage versus current characteristic such that when normal voltage appears across the electrodes, a high impedance is presented by the insulating member and when voltages in excess of normal voltage appears across the electrodes, a rapidly decreasing impedance is presented by the insulating member, thereby limiting the voltage which is sustainable across the electrodes of the switch.
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