Abstract: A power supply apparatus for use with a redundant power supply system includes a casing, a main circuit board and an airflow driving device. The casing includes a first airflow opening and a second airflow opening. The main circuit board is disposed within the casing and includes plural electronic components thereon. The airflow driving device is disposed in the middle region of the main circuit board. A cooling air is pumped by the airflow driving device to be introduced into the inner portion of the casing through one of the first airflow opening and the second airflow opening, then the heat generated from the electronic components is removed by the cooling air, and finally a heated air is exhausted through the other one of the first airflow opening and the second airflow opening.

Abstract: Disclosed is an overload protection delay circuit for use in a switching power supply for enabling the switching power supply to detect overload problems with high accuracy. The overload protection delay circuit is connected between a photo coupler and a pulse-width modulator of the switching power supply, and is consisted of an energy storage device such as a capacitor and a charging controller such as a zener diode. The charging controller is configured to set a limit value for allowing the energy storage device to be charged by an internal current source of the pulse-width modulator when the feedback signal of the switching power supply reaches the limit value. By charging the energy storage device, a time delay is added to the feedback signal so that the pulse-width modulator can accurately activate the internal overload protection mechanism without the interference of load transients.

Abstract: A fastening mechanism for fastening a detachable electronic device onto a DIN rail includes a frame, a first slab member and a first resilient element. The frame includes a base, a first extension part and a second extension part. The first extension part and the second extension part are arranged at bilateral sides of the base. A first perforation is formed between the first extension part and the base. The first slab member is movable along the bottom surface of the first extension part and has an end penetrating through the first perforation to be disposed over the base. The first resilient element is coupled to the first slab member and exerts a clamping force for claming a first extending edge of the DIN rail between the first slab member and the base.