1–12 869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
SPECIFICATIONS CHAPTER 1: INTRODUCTION
UNDERPOWER
Operating Condition:.........................................Three-phase real power
Number of Elements:........................................ 1, alarm and trip stages
Trip/Alarm Pickup Level:..................................1 to 25000 kW in steps of 1
Pickup Level Accuracy: ....................................±1.0% of reading
Hysteresis:.............................................................. 3%
Trip/Alarm Pickup Delay:.................................0 to 180.00 s in steps of 0.01
Timer Accuracy: ..................................................±3% of delay time or ±10 ms, whichever is greater, pick up to
operate
Operate Time: ......................................................<45 ms at 60 Hz; <50 ms at 50 Hz (NOTE 1)
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,
whichever is greater;
For > 2.0 x CT: ±1.5% of reading
Curve Shape:.........................................................IEEE Extremely/Very/Moderately Inverse;
ANSI Extremely/Very/Normally/Moderately Inverse;
Definite Time, IEC A/B/C and Short Inverse;
IAC Extremely/Very/Inverse/Short Inverse;
FlexCurve A/B/C/D, I
2
t, I
4
t
Curve Multiplier: ..................................................0.05 to 600.00 in steps of 0.01
Reset Time:............................................................Instantaneous, Timed
Curve Timing Accuracy: ..................................Currents > 1.03 to 20 x pickup: ± 3% of operate time or ± ½
cycle (whichever is greater) from pickup to operate
Voltage Restrained Function (51V): ............Modifies Pickup from 0.1 < V < 0.9 VT Nominal in a fixed
linear relationship
FAST PATH:
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,
whichever is greater
For > 2.0 x CT: ±1.5% of reading
Operate Time: ......................................................<12 ms typical at 3 × Pickup at 60 Hz (Phase/Ground IOC)
<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)
NOTE:
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
pickup to operate
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