| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a device for protecting a load circuit that uses thinner wires by employing a switch circuit simulating a fuse. <P>SOLUTION: A pseudo-operational expression is created by assuming the conductor resistance r, and heat capacity C of an operational expression for determining the wire temperature raised by heat generation, and of an operational expression for determining the wire temperature raised by heat dissipation, respectively, as the pseudo-conductor resistance r*, and pseudo-heat capacity C*. Wire temperature is determined using the pseudo-operational expression, and a semiconductor relay S1 is interrupted at a moment in time when the wire temperature thus determined reaches an allowable temperature. As a result, the circuit can be protected certainly at a moment in time before the wire temperature reaches an allowable temperature when the wire temperature rises due to generation of an overcurrent, or the like. Consequently, a fuse used in the prior art can be eliminated. <P>COPYRIGHT: (C)2010,JPO&INPIT |
