GE 845 Instruction Manual page 19

CHAPTER 1: INTRODUCTION
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NOTE:
NOTE
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
PHASE/NEUTRAL/GROUND TIME OVERCURRENT (51P/N/G)
Current:....................................................................Phasor or RMS
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 operate time or ± ½ cycle
Voltage Restrained Function (51V):.............Modifies Pickup from 0.1 < V < 0.9 VT Nominal in a fixed
Add 1.5 cycles to the curve time to obtain the TOC operating time, i.e., from fault inception
until operation.
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)
whichever is greater;
For > 2.0 x CT: ±1.5% of reading
ANSI Extremely/Very/Normally/Moderately Inverse;
Definite Time, IEC A/B/C and Short Inverse;
IAC Extremely/Very/Inverse/Short Inverse;
2 4
FlexCurve A/B/C/D, I t, I t
(whichever is greater) from pickup to operate
linear relationship
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)
SPECIFICATIONS
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