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 PHxPTOC can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 119: Functional module diagram
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 protection relay 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.
Protection functions
1MRS757644 H
240
620 series
Technical Manual
