ABB REG650 Technical Manual page 247

1MRK 502 043-UUS B
Technical Manual
When the parameter CurveType1 is set to Inverse, an inverse curve is selected
according to selected value for parameter K1. The minimum trip time setting of
parameter t1Min and reset time parameter ResetMultip1 also influence step operation.
However, to match the heating characteristics of the generator, the reset time is
depending on the setting of parameter K1, which must be set according to the
generators negative sequence current capacity.
=
K I t
2
2
EQUATION2112 V1 EN
Where:
I is negative sequence current expressed in per unit of the rated generator current
2
t is operating time in seconds
K is a constant [s], which depends on generator size and design
Operate
time
t1Max
(Default= 1000 s)
t1Min
(Default= 5 s)
IEC09000691 V2 EN
Figure 110: Inverse time characteristic with t1Min and t1Max
For a detailed description of inverse time characteristic, see chapter
characteristics".
The reset time is exponential and is given by the following expression:
Current protection
K1
Current I2-1>
IEC09000691-2-en.vsd
Section 8
"Inverse time
241