ABB Relion 611 Series, Technical Manual

Page: 168 / 536

4.2.1.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of 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 73: 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
Section 4
1MRS757454 D
Protection functions
162 611 series
Technical Manual