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Operation Manual 37107F
MFR 3 - Multi Function Relay
© Woodward
Page 101/165
Configuration Screens
Parameter
140
Inv.time ov.cur.
Monitor. ON
Inverse time-overcurrent monitoring
ON/OFF
ON
................ Inverse time-overcurrent monitoring is enabled. The subsequent
screens of this function are displayed.
OFF
.............. Inverse time-overcurrent monitoring is disabled. The subsequent
screens of this function are not displayed.
Parameter
141
Inv.time char.
----------------
Inverse time-overcur.: characteristic
normal inv./high inv./extremely inv.
normal inv.
........ "normal inv." tripping characteristic is used.
high inv.
............. "high inv." tripping characteristic is used.
extremely inv.
... "extremely inv." tripping characteristic is used.
Tripping of class F3 alarm
Parameter
142
Inv.time ov.cur.
Tp=0.00s
Inverse time-overcurrent: time constant Tp
0.00 to 1.98s
The time constant for t
p
is defined by this parameter.
Parameter
143
Inv.time ov.cur.
Ip=0.0*In
Inverse time-overcurrent: current constant Ip
0.1 to 3.0*In
The current constant for I
p
is defined by this parameter. This set point is dependent
upon the rated current (I
n
)
Parameter
144
Inv.time ov.cur.
I start= 0.00*In
Inverse time-overcurrent: I start
1.00 to 3.00*In
The lower tripping value for inverse time-overcurrent protection is defined by this
parameter. If the monitored current (I) is below I
Start
, the inverse time-overcurrent
protection does not trip. I
p
is used as the lower tripping value if I
Start
is configured
less than I
p
.
Characteristics
Normal Inverse
Ip = 1 x In; I start = 1.1 x In
0,01
0,1
1
10
100
1000
1
10
100
I/Ip
t[s]
tp = 1.6 s
tp = 1.0 s
tp = 0.5 s
tp = 0.2 s
tp = 0.1 s
tp = 0.05 s
I start/Ip
Figure 6-2: Inverse time-overcurrent - characteristic "normal inverse"