Undervoltage causes excessive torques and current surges which place inadmissible strains on the motor. The
voltage at which motors do no longer start up is in the range of (0.55 … 0.70) V
rated,M
. If no data are available,
use the empirical value of approx. 70% of the rated voltage for setting the parameter Threshold. Set the
Operate delay so that it slightly overlaps the tripping time of the overcurrent protection for the power-
plant auxiliary power. Unless otherwise required by the motor manufacturer, set an Operate delay
between 0.5 s and 3 s. The shorter time should be preferred.
Stage Setting Values
Threshold value Time delay
1 0.70 to 0.85 V
rated,M
(for example, 0.80 V
rated,M
)
Approx. 3 to 5 s
2 0.55 to 0.70 V
rated,M
(for example, 0.70 V
rated,M
)
0.5 s to 3 s
Settings
Addr. Parameter C Setting Options Default Setting
General
_:2311:104 General:Current-flow
criterion
•
off
•
on
on
_:2311:101 General:Threshold I> 1 A @ 100 Irated 0.030 A to 10.000 A 0.050 A
5 A @ 100 Irated 0.15 A to 50.00 A 0.25 A
1 A @ 50 Irated 0.030 A to 10.000 A 0.050 A
5 A @ 50 Irated 0.15 A to 50.00 A 0.25 A
1 A @ 1.6 Irated 0.001 A to 1.600 A 0.050 A
5 A @ 1.6 Irated 0.005 A to 8.000 A 0.250 A
Stage 1
_:481:1 Stage 1:Mode
•
off
•
on
•
test
off
_:481:2 Stage 1:Operate &
flt.rec. blocked
•
no
•
yes
no
_:481:10 Stage 1:Blk. by meas.-
volt. failure
•
no
•
yes
yes
_:481:101 Stage 1:Pickup delay
•
no
•
yes
no
_:481:3 Stage 1:Threshold 0.300 V to 200.000V 46.000V
_:481:4 Stage 1:Dropout ratio 1.01 to 1.20 1.05
_:481:6 Stage 1:Operate delay 0.00 s to 60.00 s 3.00 s
Stage 2
_:482:1 Stage 2:Mode
•
off
•
on
•
test
off
_:482:2 Stage 2:Operate &
flt.rec. blocked
•
no
•
yes
no
_:482:10 Stage 2:Blk. by meas.-
volt. failure
•
no
•
yes
yes
_:482:101 Stage 2:Pickup delay
•
no
•
yes
no
_:482:3 Stage 2:Threshold 0.300 V to 200.000 V 40.000V
6.30.5
Protection and Automation Functions
6.30 Undervoltage Protection with Positive-Sequence Voltage
SIPROTEC 5, Overcurrent Protection, Manual 755
C53000-G5040-C017-8, Edition 07.2017
To Next Page
Loading...
