The current flow monitoring function is used to detect a break in current flow safely, immediately and pole selectively. The CBF function continuously compares sampled current values from the selected end with the set threshold value CBF_1: I<. As long as current flow criteria are met the phase-selective signals CBF_1: Current flow A, CBF_1: Current flow B, CBF_1: Current flow C and the multiple signal CBF_1: Current flow Phx will be continuously issued.

In addition to this line-associated current flow monitoring function a residual current monitoring function is available which can be enabled/disabled.

For this either the residual current value measured directly at the CT or the value derived from the three phase currents may be used.

Note that this choice is only possible when a measuring input for the residual current is available.

As long as a residual current exceeding the comparator threshold is flowing, the current flow criterion is not met and the corresponding signal (CBF_1: Current flow N) is issued. When the residual current monitoring function is disabled, no monitoring is carried out and the CBF_1: Current flow N = No signal is issued continuously.