ABB REG316 4 Series Operating Instructions Manual page 126

ABB Switzerland Ltd
E. Setting instructions
Settings:
Pick-up current
Characteristic angle
Delay
Time allowed for receipt of signal
Response at the end of the
memorised power direction time
Time during which the memorised
direction is valid
Pick-up value I-Setting
"I-Setting" must be chosen high enough to prevent false tripping
or alarms from taking place and low enough to reliably detect the
minimum fault current. The setting must be sufficiently above the
maximum transient load current and allow for:
· c.t. and relay inaccuracies
· the reset ratio.
The maximum transient load current has to be determined ac-
cording to the power system operating conditions and take ac-
count of switching operations and load surges.
I
I-Setting
I
I
N
Fig. 3.5.7.1 Operating characteristic of the definite time over-
current detector
3-88
REG 316*4 1MRB520049-Uen / Rev. F
Delay
I-Setting
Angle
Delay
tWait
MemDirMode
MemDuration
HEST 905 010 C