Application Guide - NP900 Series
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A996A
Figure 3.7.1.5-227 System in case when primary phase current wiring is broken.
In this case all other conditions are met except the residual difference which is now 0 x In
and thus indicate primary side fault.
Figure 3.7.1.5-228 System in case of primary side high impedance earth fault.
In case of high impedance earth fault the CTS will not activate if the measurement
conditions are met and the calculated and measured residual current difference is not
reaching the limit. The setting Isum difference should be set according to the application
to reach maximum security and sensitivity for the network earthing.
