[dw_IEC-NI-curve_with_min-op-time-setting-appl, 1, en_US]
Figure 5-3
IEC NI Curve with Minimum Operate Time Setting Applied
To increase sensitivity, dedicated ground fault elements are used. There must be a little or no current flowing
to earth in a healthy system, so that relays can give far lower pickup levels than relays which detect excess
current (> load current) in each phase conductor. Such dedicated earth-fault relays are important where the
fault path to ground is a high-impedance (such as in highly arid areas). Such dedicated ground fault relays are
important where the system uses high values of earthing resistor/reactance and the fault current detected in
the phase conductors is limited.
Applications
5.3 Time-Delayed Overcurrent (51/51N)
Reyrolle, 7SR46 Device, Manual 75
C53000-G7040-C103-1, Edition 10.2022
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