Abstract: A grid-connected power system includes a primary power source, a back-up power source, a DC/AC inverter and a DC/DC converter. Direct current from the primary power source is supplied to the DC/AC inverter to obtain an alternating current output supplied to a utility grid when power from the utility grid is available to power a load. The output of the inverter is supplied to a selected portion of the load when power from the utility grid is unavailable to the load. Direct current from the back-up power source is supplied to the inverter through a DC/DC converter when power from the utility grid is unavailable to the load. The DC/DC converter converts the voltage of direct current from the back-up power source to direct current having a voltage compatible with the voltage of the primary power source and the inverter. The back-up power source may be charged by the primary power source or by the utility grid.

Abstract: A spring spacer assembly maintains thermal contact between a thermal transfer surface of a heat sink and a heat-generating electrical component mounted on a printed circuit board between the printed circuit board and the thermal transfer surface. The spring spacer assembly comprises a face defining a fixation segment and a deflectible finger extending from the fixation segment, and a fixation element for securing the face to the heat sink. A spacer extends from the fixation segment for passage through the printed circuit board into abutment with the thermal transfer surface. A protrusion extends from the finger for passage through the printed circuit board into contact with the heat-generating electrical component. The finger is biased toward the thermal transfer surface and urges the heat-generating electrical component into thermal contact with the thermal transfer surface. The fixation element secures the face to the heat sink with the spacer secured in abutment with the thermal transfer surface.