Beckhoff SCT Series, Documentation

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Commissioning
SCT5xxx 33 Version: 1.0
4.5 Automatic setup
The Beckhoff SCT5xxx are capable of performing automatic setup of the user selectable settings for
installations in proper condition taken as baseline. This means that during automatic setup, the SCT5xxx
automatically measures the residual currents at the plant site with different frequency ranges and integration
time settings and selects the nominal residual current limit that is at least 50% higher than the measured
value.
In this way, the SCT5xxx operate with a comfortable margin for the future development of the measured
residual current towards the trip limit of the relay. The automatic setting also suggests a suitable frequency
range and integration time.
Required steps:
• Activate the auto setting by pressing the "Rated RC limit" and "Integration time" buttons simultaneously
for more than 3 seconds.
• The device performs a series of differential current measurements with different settings.
• Proposed settings for "Rated RC limit", "Frequency range" and "Integration time" are marked with
flashing LEDs.
• The proposed change of settings should be accepted by pressing the "Test" button.
• If the change is not accepted within 10 s, the RCM returns to the old settings.
Fig. 22: Auto Setup Process
Manual setting of the 100 Hz range
The frequency range of 100 Hz is not included in the automatic setting, i.e. the user must select it
manually. The SCT5xxx always prefers the settings that make the instrument more sensitive, i.e.
higher frequency ranges and shorter integration times.