ABB Relion Technical Manual page 276

Section 8
Current protection
270
Operate
time
t1Max
(Default= 1000 s)
t1Min
(Default= 5 s)
IEC09000691 V2 EN
Figure 122: 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:



ResetMultip
[ ]
=
ResetTime s



I

NS

 
I
Pickup
ANSIEQUATION2111 V1 EN
Where
I is the measured negative sequence current
NS
I is the desired pickup level in pu of rated generator current
Pickup
ResetMultip
is multiplier of the generator capability constant
time of inverse time characteristic
IEC09000691-2-en.vsd



⋅
K K 1

2


 −
1

 
1MRK 502 048-UUS A
K1
Current I2-1>
"Inverse time
K equal to setting K 1 and thus defines reset
Technical manual
(Equation 74)