Negative sequence inverse time characteristic
Negative sequence current
T
im
e
d
e
la
y
I2
tMax
tMin
IEC08000355-2-en.vsd
1
10
100
1000
10000
0.01 0.1 1 10 100
IEC08000355 V2 EN-US
Figure 202: Inverse Time Delay characteristic, step 1
The example in figure
202 indicates that the protection function has a set minimum trip
time t1Min of 5 sec. The setting t1Min is freely settable and is used as a security
measure. This minimum setting assures appropriate coordination with for example line
protections. It is also possible to set the upper time limit, t1Max.
9.12.3.2
Pickup sensitivity
GUID-1D038486-7086-466F-A92F-30E1A47D0298 v3
The trip pickup levels Current I2-1>
and I2-2> of NS2PTOC (46I2) are freely settable
over a range of 3 to 500 % of rated generator current IBase. The wide range of pickup
setting is required in order to be able to protect generators of different types and sizes.
After pickup, a certain hysteresis is used before resetting pickup levels. For both steps
the reset ratio is 0.97.
9.12.3.3 Alarm function
GUID-1B932D89-3233-4841-977A-5B61346B057B v2
The alarm function is operated by PICKUP signal and used to warn the operator for an
abnormal situation, for example, when generator continuous negative sequence current
capability is exceeded, thereby allowing corrective action to be taken before removing
1MRK 502 071-UUS A Section 9
Current protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 423
Application manual
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