GE 845 - Page 23

CHAPTER 1: INTRODUCTION SPECIFICATIONS
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 1–13
PHASE DIRECTIONAL OVERCURRENT (67P)
Relay Connection: ..............................................90º(Quadrature)
Quadrature Voltage:..........................................ABC phase seq.: phase A (Vbc), phase B (Vca), phase C (Vab);
ACB phase seq.: phase A (Vcb), phase B (Vac), phase C (Vba)
Polarizing Voltage Threshold:........................0.050 to 3.000 x VT in steps of 0.001 x VT
Current Sensitivity Threshold:.......................0.05 x CT
Characteristic Angle:.........................................0º to 359º in steps of 1°
Angle Accuracy: ..................................................± 2º
Operation Time (FlexLogic™ operands): ..Reverse to Forward transition: < 12 ms, typically;
Forward to Reverse transition: <8 ms, typically
NEUTRAL DIRECTIONAL OVERCURRENT (67N)
Directionality: .......................................................Co-existing forward and reverse
Polarizing: ...............................................................Voltage, Current, Dual
Polarizing Voltage:..............................................V_0 or VX
Polarizing Current:..............................................Ig
Operating Current: .............................................I_0
Level Sensing:.......................................................3 x (|I_0| – K x |I_1|), Ig
Restraint, K: ...........................................................0.000 to 0.500 in steps of 0.001
Characteristic Angle:.........................................-90º to 90º in steps of 1°
Limit Angle: ............................................................40º to 90º in steps of 1°, independent for forward and
reverse
Angle Accuracy: ..................................................±2º
Pickup Level:..........................................................0.050 to 30.000 x CT in steps of 0.001 x CT
Dropout Level: ......................................................97 to 98% of Pickup
Operate Time (no direction transition):.....< 16 ms at 3 x Pickup at 60 Hz
< 20 ms at 3 x Pickup at 50 Hz
GROUND DIRECTIONAL OVERCURRENT (67G)
Directionality: .......................................................Co-existing forward and reverse
Polarizing: ...............................................................Voltage
Polarizing Voltage:..............................................V_0 or VX
Polarizing Current:..............................................Isg
Operating Current: .............................................Ig
Level Sensing:.......................................................Ig, Isg
Characteristic Angle:.........................................-90º to 90º in steps of 1°
Limit Angle: ............................................................40º to 90º in steps of 1°, independent for forward and
reverse
Angle Accuracy: ..................................................±2º
Pickup Level:..........................................................0.050 to 30.000 x CT in steps of 0.001
Dropout Level: ......................................................97 to 98%
Operate Time (no direction transition):.....< 12 ms typical at 3 x Pickup at 60 Hz
< 15 ms typical at 3 x Pickup at 50 Hz
RESTRICTED GROUND (EARTH) FAULT (87G)
Operating Parameter:.......................................Ia, Ib, Ic and Ig (Fundamental Phasor Magnitude)
Pickup Level:..........................................................0.050 to 30.000 x CT in steps of 0.001 x CT (phase CT)
Ground Supervision Level:..............................0.050 to 30.000 x CT in steps of 0.001 x CT (ground CT)
Dropout Level: ......................................................97 to 98% of Pickup
Slope Range: .........................................................0 to 100% in steps of 1%
Pickup Delay: ........................................................0.000 to 6000.000 s in steps of 0.001 s
Level Accuracy:....................................................For 0.1 to 2.0 x CT: ±0.5% of reading or ±0.4% of rated,
whichever is greater
For > 2.0 x CT: ± 1.5% of reading
Operate Time:.......................................................<25 ms at 1.1 x slope x Imax at 60 Hz, typically
<30 ms at 1.1 x slope x Imax at 50 Hz, typically
Timing Accuracy:................................................±3% of delay setting or ± ¼ cycle (whichever is greater) from
pickup to operate