Abstract: A method and apparatus are provided for short circuit protection in a DC current source. A rectifying circuit arranged to generate a DC output can coupled to an AC source and a capacitor filter circuit can be provided to smooth the DC output. A short circuit detection unit can also be provided for monitoring at least one voltage across the capacitor filter circuit and generating a fault signal. A controller can then limit current through the capacitor filter circuit when the fault signal implies that the monitored voltage has fallen below a threshold value.