| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method and apparatus for overcurrent protection capable of surely protecting a load from overcurrent. <P>SOLUTION: A momentary operation deciding means S1 performs momentary operation decision based on comparison between a momentary operation detection threshold and a ratio R between a coil current Ic and a nominal current value Ir. A time-limit operation deciding means S2 performs time-limit operation decision, based on comparison between an elapsed time since reaching a prescribed real current value and an overcurrent detection time limit, with the overcurrent detection time limit being set based on the ratio R between the coil current Ic and the nominal current value. If the instantaneous operation decision or the time-limit operation decision is made, supplying of a current to an electromagnetic coil is cut off. The electromagnetic coil is surely protected by employing both an instantaneous operation, in which a large current is detected at once and a time-limit operation in which a current equal to or above a nominal current is detected at a time limit according to a current value. <P>COPYRIGHT: (C)2004,JPO</p> |
