Application Manual CDA3000
5-89
5 Software functions
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Fault current monitoring by differential current monitoring
The implemented differential current monitoring is based on typical RCM
differential current protection devices.
Based on the scaleable response threshold of the ground fault detector
by way of parameter 531-EFSCL, fault currents can be detected and the
device power stage can be disabled. Error message E-OC-110 is deli-
vered.
The basic principle of electrical engineering requires that all conductors
(except grounding leads) are routed through a converter. In an error-free
system the sum total of all currents is then equal to zero, so no differential
current is evaluated by the software via the current sensors of the inver-
ter.
As a result, symmetrical insulation errors occurring in all motor cables
against PE or ground cannot be detected by the differential current moni-
tor.
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