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.