ABB Switzerland Ltd REG 316*4 1MRB520049-Uen / Rev. F
3-290
Reset time of the current detector t
Reset
The current detector reset time is determine by the power sys-
tem configuration as follows:
· Power system time constant up to 300 ms
· Fault current up to 40 I
N
Primary c.t’s TPX: t
Reset
= 28 ms (I
Setting
³ 0.2 I
N
)
Primary c.t’s TPY: t
Reset
= 28 ms (I
Setting
³ 1.2 I
N
)
t
Reset
= 38 ms (I
Setting
³ 0.4 I
N
)
Safety margin t
Margin
A safety margin of 20 ms is recommended.
Reset times ‘t Drop Retrip’ and ‘t Drop BuTrip’
The function includes two independently adjustable signal reset
delays.
‘t Drop Retrip’ determines the reset delay for the following sig-
nals: 23305 Trip t1
23315 Trip t1 L1
23320 Trip t1 L2
23325 Trip t1 L3
23345 Red Trip L1
23350 Red Trip L2
23355 Red Trip L3
23330 Retrip t1
23360 Uncon Trip t1
23380 Ext Trip t1.
‘t Drop BuTrip’ determines the reset delay for the following sig-
nals:
23310 Trip t2
23370 EFP Bus Trip
23335 Backup Trip t2
23365 Uncon Trip t2.
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