Abstract: Power supply apparatus (10) comprising a circuit board (11) and one or more power devices (12) attached to a first surface (11a) of the circuit board (11). A plate (14a) composed of a thermally conductive plastic faces the first surface of the circuit board (11). A thermally conductive encapsulant (15) is provided between the first surfaces (11a) of the circuit board (11) and the plate (14a). The circuit board (11) comprises one or more heat-spreading layers (212*,213*) configured to enhance heat transfer in directions parallel to the first surface (11a) of the circuit board (11). The first surface (14aa?) of the plate (14a) may also be irregular and comprises one or more first regions (32) and one or more second regions (31) that are further from the first surface (11a) of the circuit board (11) than the one or more first regions (32), with the one or more power devices (12) being aligned with the one or more second regions (31).

Abstract: A three-phase electronic electricity meter that includes a power supply circuit operable to create a constant voltage output when receiving a variable voltage input. The power supply circuit of the electricity meter receives a three-phase line voltage and converts the variable three phase line voltage to a constant DC output. The power supply circuit includes a current limiting circuit to suspend operation of the power converter when the current exceeds a selected value. The power supply circuit includes an over voltage protection that limits the maximum voltage applied to the switching component of the power supply circuit. Both the over voltage protection circuit and the current limiting circuit suspend operation of the power converter to prevent damage to the operating components of the power supply circuit.