| 摘要 |
A four terminal varistor is shown as a device for providing fail-safe circuit protection under certain conditions. The failure of any lead connected to the four terminal varistor will shut down the protected load so that the load cannot operate under unsafe conditions. By its nature, a varistor can absorb voltage peaks and protect a load from high voltage and/or a current resulting from high voltage. One pair of leads from the varistor is connected to the power supply and the other pair of leads to the load. Thus, if any lead is broken, there will be no power to the load. A variation provides additional protection in the event the metal coating on the semiconductor, to which two of the leads are attached, becomes detached from the semiconductor. In case of such detachement, the electrical connection between the two leads is broken. For this purpose, the metalized coating on the semiconductor is divided into two separate areas, one for each lead. The areas are electrically coupled together by a mechanically weak link and/or a link which may be embedded within the semiconductor material.
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