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To provide an effective protection for the generator for external unbalanced conditions,
NS2PTOC (46I2) is able to directly measure the negative sequence current. NS2PTOC
(46I2) also has a time delay characteristic which matches the heating characteristic of the
generator
2
2
I t
K
=
as defined in standard IEEE C50.13.
where:
I
2
is negative sequence current expressed in per unit of the rated generator
current
t
is operating time in seconds
K
is a constant which depends of the generators size and design
NS2PTOC (46I2) has a wide range of
K
settings and the sensitivity and capability of
detecting and tripping for negative sequence currents down to the continuous capability of
a generator.
In order to match the heating characteristics of the generator a reset time parameter can be
set.
A separate definite time delayed output is available as an alarm feature to warn the
operator of a potentially dangerous situation.
8.9.3
Function block
ANSI08000359-2-en.vsd
NS2PTOC (46I2)
I3P*
BLOCK
BLK1
BLK2
TRIP
TRST1
TRST2
PICKUP
PU_ST1
PU_ST2
ALARM
NSCURR
ANSI08000359 V2 EN
Figure 121:
NS2PTOC (46I2) function block
Section 8
1MRK 502 048-UUS A
Current protection
266
Technical manual
Summary of Contents for 650 series
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