A remote power unit for providing direct current power to a remote power receiver in a direct current power system is provided. A residual current protection circuit comprises a first switch, which opens a positive voltage rail, and a second switch, which open a negative voltage rail. A first current sensor measures a first residual current between the first switch and the remote power receiver, while the first switch is closed and the second switch is opened. A second current sensor measures a second residual current between the second switch and the remote power receiver, while the second switch is closed and the first switch is open. A controller detects a residual current event, if the first residual current and/or the second residual current are above a residual current threshold.
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