Siemens SICAM V01.00 Manual page 54

Device Functions
4.2 Fault Detection
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Range Change Monitoring Time (T1): This timer is designed to monitor the transition between
current ranges when there is a change in the load current. It is activated when the load current crosses
the maximum limit of a current range. The purpose of T1 is to track the duration during which the load
current remains within the new range. If the load current remains within the new range for the entire
duration of the T1 timer, it confirms a range change.
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Range Change Memorizing Time (T2): This timer, if configured, assists in managing dynamic load
currents. T2 monitors the load current within the new range after a range change has been confirmed
by T1. It is responsible for triggering actions based on the duration the load current stays within the
new band. If the load current stays within the new band, no further changes are made. However, if the
load current drops below the minimum of the new range, the fault threshold automatically reverts to its
original value.
Let us go through an example of how the auto threshold function calculates the fault threshold and utilizes
timers for dynamic load currents
Scenario 1: If the load current is around 30 A and the auto-threshold fault factor is set as 2x.
Calculation of Fault Threshold
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Load Current: Approximately 30 A
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Auto-threshold fault factor: 2x
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Resulting fault threshold: 100 A (2 times the maximum load current in the nominal current range 20 A to
50 A)
Scenario 2: Load Current Rising from 30 A to 60 A
Range Change Monitoring Timer (T1) Activation
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As the load current crosses the maximum limit of the current range (50 A), the T1 timer starts.
Range Change Confirmation
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Duration Condition: If the load current remains within the new range for the entire duration of the T1
timer, it confirms a range change.
Fault Threshold Adjustment
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Upon confirming the range change, the fault threshold is adjusted to 2 times the maximum value of the
new range.
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The new fault threshold becomes 200 A (2 times the maximum load current in the nominal current range
40 A to 100 A)
Range Change Memorizing Timer (T2)
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T2 configuration: The T2 timer monitors the load current within the new range.
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If the load current stays within the new band, no further changes are made.
•
Reversion to Original Value: However, if the load current drops below the minimum load current value of
the new range, the fault threshold automatically reverts to its original value 100 A.
The same principles apply if the load current drops to a lower current range, relevant timers are auto triggered
and fault thresholds are adjusted accordingly.
In summary, the auto threshold function calculates the fault threshold based on the load current and the
configured fault factor. It employs timers (T1 and T2) to monitor load current changes and determine current
range transitions. The fault threshold is dynamically adjusted based on the maximum value of the new current
range, with the option to revert to the original value if the load current exceeds or falls below specific ranges.
NOTE
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Range Change Memorizing Timer (T2) can also be configured to 0 s to disable its function.
54 SICAM, Fault Sensor Indicator V2.0 B-Sensor, Manual
E50417-H8940-C656-A1, Edition 08.2023