7.6.7 Operation principle
Negative sequence based overcurrent function (DNSPTOC, 46) has two settable
current levels, setting parameters PickupCurr_OC1 and PickupCurr_OC2. Both
features have definite time characteristics with settings tDef_OC1 and tDef_OC2
respectively. It is possible to change the direction of these steps to forward, reverse or
non-directional by setting parameters DirMode_OC1 and DirMode_OC2. At too low
polarizing voltage the overcurrent feature can be either blocked or non-directional.
This is controlled by settings ActLowVolt1_VM and ActLowVolt2_VM.
7.6.8 Technical data
Table 64: DNSPTOC (46) Technical data
Function Range or value Accuracy
Operate current (2.0 - 5000.0) % of
IBase
± 1.0% of I
r
at I <I
n
± 1.0% of I at I > I
n
Reset ratio > 95 % -
Low voltage level for memory (0.0 - 5.0) % of
VBase
< ± 0.5% of V
n
Relay characteristic angle (-180 - 180) degrees ± 2.0 degrees
Relay operate angle (1 - 90) degrees ± 2.0 degrees
Timers (0.00 - 6000.00) s ± 0.5% ± 25 ms
Operate time, non-directional 30 ms typically at 0 to 2 x I
set
20 ms typically at 0 to 10 x I
set
-
Reset time, non-directional 40 ms typically at 2 to 0 x I
set
-
Operate time, directional 30 ms typically at 0 to 2 x I
set
20 ms typically at 0 to 10 x I
set
-
Reset time, directional 40 ms typically at 2 to 0 x I
set
-
Critical impulse time 10 ms typically at 0 to 2 x I
set
2 ms typically at 0 to 10 x I
set
-
Impulse margin time 15 ms typically -
Dynamic overreach < 10% at t = 300 ms -
1MRK 505 277-UUS C Section 7
Current protection
121
Technical Manual
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