| 摘要 |
Power supply apparatus with overload protection comprising a switch (1) responsive to an input signal (6) for switching between an ON-state for supplying current from a source of power to a load (4) and an OFF-state for interrupting the supply of current to the load, and protection means (5, 7, 8) responsive to an overload condition to switch the switch to the OFF-state. The protection means (5, 7, 8) is responsive to a first overload condition (OCHI, OVT) during an initial phase (10) after the switch (1) switches to the ON-state so as to switch the switch back to the OFF-state and maintain the switch in the OFF-state. The protection means is subsequently responsive to a second overload condition (OCLO) if the first overload condition is not detected during the initial phase so as to switch the switch to the OFF-state and subsequently switch the switch back to the ON-state after an interval of time. The protection means is responsive to the current exceeding a first threshold value in detecting the first overload condition (OCHI), and is responsive to the current exceeding a second threshold value in detecting the second overload condition (OCLO), the second threshold value being lower than the first threshold value. The protection means is responsive to a temperature of the switch means exceeding a temperature threshold value in detecting at least the first overload condition (OVT).
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