700results about "Varistor cores" patented technology

A voltage suppression device for suppressing voltage surges in an electrical circuit, comprised of a voltage sensitive element having a predetermined voltage rating, the voltage sensitive element increasing in temperature as voltage applied across the voltage sensitive element exceeds the voltage rating. Terminals are provided for electrically connecting the voltage sensitive element between a power line of an electrical circuit and a ground or neutral line of the electrical circuit. A normally closed, thermal switch is electrically connected in series with the voltage sensitive element between one line of the electrical circuit and the voltage sensitive element, the thermal switch being thermally coupled to the voltage sensitive element wherein the thermal switch moves from a normally closed position to an open position to form a gap between the thermal switch and the voltage sensitive element when the temperature of the voltage sensitive element reaches a level indicating an over-voltage condition. When the thermal switch moves to the open position, residual follow on current is shunted by a fuse element connected in parallel with the thermal switch. Current flows through the fuse element until the fuse element melts. Electrical arcing is contained inside the fuse until extinguished.

A varistor is provided which can be driven at a low voltage, has a small leak current, and can realize a high ESD resistance and a high surge resistance. The varistor is formed using a ceramic composition for a varistor which contains zinc oxide as a primary component and sub-components including praseodymium at a content of 0.05 to 3.0 atomic percent of the total, cobalt at a content of 0.5 to 10 atom percent of the total, at least one of potassium, sodium, and lithium at a total content of 0.005 to 0.5 atom percent of the total, at least one of aluminum, gallium, and indium at a total content of 2×10−5 to 0.5 atom percent of the total, and zirconium at a content of 0.005 to 5.0 atom percent of the total.

The variable resistance element of the present invention is a variable resistance element having an electrode, the other electrode, and a metal oxide material sandwiched between the electrodes and having an electrical resistance, between the electrodes, changing reversibly in response to a voltage applied between the electrodes. The variable resistance element further includes, inside the metal oxide material, a low resistance material having a lower electrical resistance than the metal oxide material and being out of contact with at least either one of the electrodes. This makes it possible to reduce a forming voltage for providing a conductive section inside the metal oxide material, without causing a leakage current to increase.

A monolithic semiconductor ceramic capacitor includes semiconductor ceramic layers made of a semiconductor ceramic having a Sr site and a Ti site. The semiconductor ceramic satisfies the inequality 1.000<m≦1.020, wherein m represents the molar ratio of the Sr site to the Ti site. The semiconductor ceramic contains crystal grains and has grain boundary layers. The crystal grains contain a donor element such as La or Sm in the form of a solid solution. The grain boundary layers contain an acceptor element such as Mn, Co, Ni or Cr. The amount of the acceptor element therein is equal to or less than 0.5 mol (preferably 0.3 to 0.5 mol) per 100 mol of Ti. The crystal grains have an average size of 1.0 μm or less (preferably 0.5 to 0.8 μm). Therefore, the monolithic semiconductor ceramic capacitor has good electrical properties, good resistivity, good dielectric strength, and high reliability and is suitable for thin or compact apparatuses.