Manual 37353A
MFR 13 Packages - Protection Relay
Page 50/91
© Woodward
Configuration Screens
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.
Inv.time char.
----------------
Inverse time-overcurrent: characteristic
Normal / High / Extreme
Normal.
........"Normal inverse" characteristic used
High
.............."Very inverse" characteristic used
Extreme
......."Extremely inverse" characteristic used
Inv.time ov.cur.
Tp=0.00s
Inverse time-overcurrent: time constant Tp
0.01 to 1.99s
The time constant for t
p
is defined by this parameter.
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
)
Inv.time ov.cur.
I start= 0.00*In
Inverse time-overcurrent: I Start
1 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"