Figure 3.24-3 Initiation module diagram
The measured neutral unbalance current is compared to the set 51NA_Cur_Str. If the measured
value exceeds the set 51NA_Cur_Str and no block signal is activated, the timer and 51NA_Str
signal are activated. If the 51NA_Ena_Mult input is active, the 51NA_Cur_Str value setting is
multiplied by the 51NA_Mult_Cur setting.
Where:
51NA_Ena_Mult is a binary input to enable or disable the start multiplier.
51NA_Ena is used to enable or disable the protection.
51NA_Cur_Str is the start value.
51NA_Mult_Cur is the multiplier for scaling the start value.
NOTICE!
Do not set the multiplier setting 51NA_Mult_Cur higher than necessary. If the value is
too high, the function may not operate at all during an inrush followed by a fault, no
matter how severe the fault is.
The start value multiplication is normally done when the inrush detection function
(OCR_INR) is connected to the Ena_Mult input by Three phase inrush function
OCR_INR.
3.24.2.2 Timer element
The functional module diagram is shown as below:
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