IDMT setting parameters
k Time dial setting for IDMT
A IDMT Constant
B IDMT Constant
C IDMT Constant
0.01…25.00 step 0.01
0…250.0000 step 0.0001
0…5.0000 step 0.0001
0…250.0000 step 0.0001
Inaccuracy
-IDMT operating time
-IDMT minimum operating time; 20 ms
±1.5 % or ±20 ms
±20 ms
Instant operation time
Start time and instant operation time (trip):
(Im/Iset ratio > 3)
(Im/Iset ratio 1.05…3)
<40 ms (typical 30 ms)
<50 ms
Reset
Reset ratio
-Current
-U1/I1 angle
97 % of pick-up current setting
2.0 °
Reset time setting
Inaccuracy: Reset time
0.010 … 10.000 s, step 0.005 s
±1.0 % or ±50 ms
Instant reset time and start-up reset
<50 ms
Note!
Minimum voltage for direction solving is 1.0 V secondary. During three phase short circuits the
angle memory is active for 0.5 seconds in case the voltage drops below 1.0 V.
9.2.1.4. Directional earth fault(67N) Iodir>
Table. 9.2.1.4. - 265. Directional earth fault(67N)
Input signals
Input current magnitudes
Input voltage magnitude
Residual current fundamental freq RMS
Residual current TRMS
Residual current peak-to-peak
Zero sequence voltage fundamental freq RMS
Pick-up
Used current magnitude
Used voltage magnitude
Measured residual current I01 (1 A)
Measured residual current I02 (0.2 A)
Calculated residual current I0Calc (5 A)
Measured zero sequence voltage U0
Calculated zero sequence voltage U0
Characteristic direction
Unearthed (Varmetric 90°)
Petersen coil GND (Wattmetric 180°)
Grounded
(Adjustable sector)
When
grounded
mode is active
-Trip area center
-Trip area size (+/-)
0.00…360.00 deg, setting step 0.10 deg
45.00…135.00 deg, setting step 0.10 deg
Pick-up current setting
Pick-up voltage setting
0.005…40.00 x In, setting step 0.001 x In
1.00…50.00 % U0n, setting step 0.01 x In
Inaccuracy
Starting I01 (1 A)
Starting I02 (0.2 A)
Starting I0Calc (5 A)
Voltage U0 and U0Calc
U0/I0 angle (U > 15 V)
U0/I0 angle (U = 1…15 V)
±0.5 %I0
SET
or ±3 mA (0.005…10.0 x I
SET
)
±1.5 %I0
SET
or ±1.0 mA (0.005…25.0 x I
SET
)
±1.5 %I0
SET
or ±15 mA (0.005…4.0 x I
SET
)
±2.5 %U0
SET
±0.1 ° (I0Calc ±1.0 °)
±1.0 °
Operation time
De nite time function operating time setting
0.00…1800.00 s, setting step 0.005 s
AQ-T257
Instruction manual
Version: 2.00
337
© Arcteq Relays Ltd