Circuit protection devices which comprise conductive polymer PTC elements and which will provide repeated protection against sudden increases in current to high levels, e.g. 5 amps or more, in circuits which operate at, or are subject to fault conditions arising from, voltages greater than 100 volts,...http://www.google.com/patents/US4413301?utm_source=gb-gplus-sharePatent US4413301 - Circuit protection devices comprising PTC element
