Direct current in local networks

Distribution of direct current in local networks.

A report from the Swedish Installation Federation.
In this report, we describe how DC components and high-frequency, conductive disturbances can affect residual current breakers and the extent to which the interference can cause malfunction of type A residual current breakers.

Type A means that the residual current breaker can handle pulses of direct current, but not a more continuous such current to any great extent. If the DC component of the fault current passing through the residual current breaker is greater than 6 mA, it will stop working. It will get stuck in the switched-on position and will not disconnect when it should.
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