Operation Principle - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.1.2.4
242

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
PH3xPTOC is used as single-phase and three-phase non-directional overcurrent and
short circuit protection. The phase operation mode is selected with the Operation
curve type setting. The operation is further specified with the Num of start phases
setting, which sets the number of phases in which the current must exceed the set
current start value before the corresponding start and operating signals can be
activated.
The operation of PH3xPTOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
GUID-07A8AE81-64A6-496E-AE20-2894B5474046-CN V1 EN
Figure 116: 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.
1MRS757644 F
620 series
Technical Manual