In the DT mode, the function operates after a predefined operate time and resets
when the fault current disappears. The IDMT mode provides current-dependent
timer characteristics.
The function contains a blocking functionality. It is possible to block function
outputs, timers or the function itself, if desired.
4.1.1.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of three-phase non-directional overcurrent protection can be
described by using a module diagram. All the modules in the diagram are explained
in the next sections.
A070552 V1 EN
Figure 70: Functional module diagram. I_A, I_B and I_C represent phase
currents.
Level detector
The measured phase currents are compared phasewise to the set Start value. If the
measured value exceeds the set Start value, the level detector reports the exceeding
of the value to the phase selection logic. If the ENA_MULT input is active, the Start
value setting is multiplied by the Start value Mult setting.
The IED does not accept the Start value or Start value Mult setting
if the product of these settings exceeds the Start value setting range.
The start value multiplication is normally done when the inrush detection function
(INRPHAR) is connected to the ENA_MULT input.
Section 4 1YHT530004D05 D
Protection functions
140 615 series
Technical Manual
To Next Page
Loading...
Need help?
General
