Woodward
Manual MRIK3-C EN
42
DOK-TD-MRIK3-C Rev. A
6.5
Protection
Parameters
6.5.1
Pickup current for phase Overcurrent element
The setting value for this parameter that appears on the display is related to the nominal current
(I
N
) of the relay. This means: pickup current (Is) = displayed value x nominal current (I
N
) e.g. dis-
played value = 1.25 then, Is = 1.25 x I
N
.
6.5.2
Trip Characteristics for the Phase Overcurrent Element (I>)
There are the following standard trip time characteristics available:
DEFT -
Definite Time (definite time overcurrent protection)
NINV -
Normal
inverse
VINV -
Very
inverse
EINV -
Extremely
inverse
RINV -
RI-Inverse
LINV -
Long term Inverse
6.5.3
Tripping Time or Time Factor for the Phase Overcurrent Element
Normally, after change of the trip characteristics, the tripping time or the time factor also has to be
changed accordingly. In order to avoid an unsuitable combination between trip characteristics and
tripping time or time factor, the following measures are initiated by the MRIK3-C:
The LED for adjustment of the tripping time or time factor starts to flash after the trip characteristics
have changed. By this warning signal the operator is reminded to adjust the tripping time or time
factor to the changed operational mode or trip time characteristics. This warning signal keeps flash-
ing until the tripping time or time factor are re-adjusted. If re-adjustment has not been done within 5
minutes (the time to enable parameter setting), then the processor sets the tripping time or time
factor to the highest sensible value (smallest possible tripping time
When adjusting to the “Definite Time” trip characteristic, the definite tripping time displayed is
shown as seconds (e.g. 0.35 = 0.35s). By pressing push-buttons <+><-> this time can be changed
step by step in the range 0.04s – 300s
When adjusting to the “Inverse Time” trip characteristics, the time factor (tI>) is displayed. This fac-
tor can be changed also by push buttons <+><-> step by step in the range 0.05 – 20.0.
If the tripping time or time factor is set to infinite long (on the display “EXIT” is shown) then trip of
the relay overcurrent element is blocked. The WARNING/ ALARM function is still active. During this
time LEDs I> and t> are red.