Operation Principle - ABB RELION Series Technical Manual

Section 4
Protection functions
4.2.1.4
264

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of (F)EFxPTOC can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
A070437 V3 EN
Figure 140: Functional module diagram
Level detector
The operating quantity can be selected with the setting Io signal Sel. The selectable
options are "Measured Io" and "Calculated Io". The operating quantity is compared to
the set Start value. If the measured value exceeds the set Start value, the level detector
sends an enable-signal to the timer module. 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.
Timer
Once activated, the timer activates the START output. Depending on the value of the
Operating curve type setting, the time characteristics are according to DT or IDMT.
When the operation timer has reached the value of Operate delay time in the DT mode
or the maximum value defined by the inverse time curve, the OPERATE output is
activated.
When the user-programmable IDMT curve is selected, the operation time
characteristics are defined by the parameters Curve parameter A, Curve parameter B,
Curve parameter C, Curve parameter D and Curve parameter E.
If a drop-off situation happens, that is, a fault suddenly disappears before the operate
delay is exceeded, the timer reset state is activated. The functionality of the timer in
the reset state depends on the combination of the Operating curve type, Type of reset
curve and Reset delay time settings. When the DT characteristic is selected, the reset
1MRS758755 A
REC615 and RER615
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