Rockwell Automation T80008 Application Note MCB Discrimination - Manual (Page 2)

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AN-T80008 MCB Discrimination
Issue 2 Feb 07 AN-T80008 2
Figure 1 Several circuit-breakers are concerned by the fault I
f
Several types of over currents may be encountered in an installation:
• overloads, short-circuits, inrush currents, as well as:
• earth faults, transient currents due to voltage dips or momentary loss of supply.
The MCB characteristic curves must be checked against the power supply overload graph to ensure
that the MCB trips before the power supply in an overload situation.