GE 845 Instruction Manual page 22

SPECIFICATIONS
NOTE:
NOTE:
1–12
NEGATIVE SEQUENCE TIME OVERCURRENT (51_2)
Operating Parameter: ...................................... I_2 (Fundamental Phasor Magnitude)
Pickup Level: ......................................................... 0.050 to 30.000 x CT in steps of 0.001 x CT
Dropout Level:...................................................... 97 to 98% of Pickup
Level Accuracy: ................................................... For 0.1 to 2.0 x CT:± 0.5% of reading or ±0.4% of rated,
Curve Shape:......................................................... IEEE Extremely/Very/Moderately Inverse
Curve Multiplier: .................................................. 0.05 to 600.00 in steps of 0.01
Reset Time: ............................................................ Instantaneous, Timed
Curve Timing Accuracy:.................................. Currents > 1.1 x pickup: ± 3% of curve delay or ± ½ cycle
Add 1.5 cycles to the curve time to obtain the TOC operating time, i.e., from fault inception
until operation.
PHASE/NEUTRAL/GROUND INSTANTANEOUS OVERCURRENT (50P/N/G)
Current (for Phase IOC only): ......................... Phasor or RMS
Current (for Neutral/Ground IOC only):..... Fundamental Phasor Magnitude
Pickup Level: ......................................................... 0.050 to 30.000 x CT in steps of 0.001 x CT
Dropout Level:...................................................... 97 to 98% of Pickup
Level Accuracy: ................................................... For 0.1 to 2.0 x CT: ±0.5% of reading or ±0.4% of rated,
Operate Time: ...................................................... <12 ms typical at 3 × Pickup at 60 Hz (Phase/Ground IOC)
Operating time specifications given above are applicable when RMS inputs are used.
Typical times are average operate times over multiple test cases.
Timer Accuracy:.................................................. ±3% of delay setting or ± ¼ cycle (whichever is greater) from
NEGATIVE SEQUENCE INSTANTANEOUS OVERCURRENT (50_2)
Current:.................................................................... I_2 Fundamental Phasor Magnitude
Pickup Level: ......................................................... 0.050 to 30.000 x CT in steps of 0.001 x CT
Dropout Level:...................................................... 97 to 98% of Pickup
Level Accuracy: ................................................... For 0.1 to 2.0 x CT: ±0.5% of reading or ± 0.4% of rated,
Pickup Time Delay: ............................................ 0.000 to 6000.000 s in steps of 0.001 s
Dropout Time Delay:......................................... 0.000 to 6000.000 s in steps of 0.001 s
Overreach: ............................................................. < 2%
Operate Time: ...................................................... < 12 ms typical at 3 x Pickup at 60 Hz
Timer Accuracy:.................................................. ±3% of delay setting or ± ¼ cycle (whichever is greater) from
whichever is greater
For > 2.0 x CT: ± 1.5% of reading
ANSI Extremely/Very/Normally/Moderately Inverse
IEC Curve A/B/C and Short Inverse
IAC Extreme/Very/Inverse/Short Inverse
FlexCurve™ A, FlexCurve™ B, FlexCurve™ C, FlexCurve™ D
2 4
I t, I t, Definite Time
(whichever is greater) from pickup to operate
whichever is greater
For > 2.0 x CT: ±1.5% of reading
<16 ms typical at 3 × Pickup at 60 Hz (Neutral IOC)
<15 ms typical at 3 × Pickup at 50 Hz (Phase/Ground IOC)
<20 ms typical at 3 × Pickup at 50 Hz (Neutral IOC)
pickup to operate
whichever is greater
For > 2.0 x CT: ± 1.5% of reading
< 15 ms typical at 3 x Pickup at 50 Hz
pickup to operate
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 1: INTRODUCTION