ABB REX 521 - Is2 T N

104
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
7.1.14. Is2t n<
The motor start-up supervision protection function block Is2t n< is designed to
monitor thermal stress during a single motor start-up.
Fig. 7.1.14.-1 Function block symbol of Is2t n<
1
Includes the delay of signal relay
2
Includes the delay of heavy-duty output relay
Three-phase start-up supervision for motor
Operation mode Not in use
lIt
lIt & stall
Start current 1.0...10.0 x In
Start time 0.3...250.0 s
Time limit 1.0...500.0 s
Countdown rate 2.0...250.0 s/h
Stall time 2.0...120.0 s
Note! The values below apply when f/f
n
= 0.95...1.05:
Operation accuracies Current measurement: ±2.5% of set value or ±0.01 x In
Stall time accuracy ±2% of set value or ±20 ms
f/
fn
= 0.95...1.50
Internal time <22 ms
Total time <30 ms
1
f/fn = 0.50...0.95
Internal time <32 ms
Total time <40 ms
1
Start time f/fn = 0.95...1.50
Internal time <22 ms
Total time <30 ms
1
f/fn = 0.50...0.95
Internal time <32 ms
Total time <40 ms
1
Reset ratio Typical 0.95 (range 0.95...0.98)
Retardation time Total retardation time when current drops below the start
value <50 ms
2
Frequency dependence of settings and
operating times
Frequency dependence is described above
GROUP
S TALL_IND
Is2t n<
START
TRI
P
STAL
L
RESTAR
T