SEL-787-2, -3, -4 Data Sheet
Schweitzer Engineering Laboratories, Inc.
38
Processing Specifications and Oscillography
AC Voltage and
Current Inputs:
32 samples per power system cycle
Frequency Tracking Range: 15–70 Hz (requires ac voltage inputs
option)
Digital Filtering:
One-cycle cosine after low-pass analog
filtering. Net filtering (analog plus
digital) rejects dc and all harmonics
greater than the fundamental.
Protection and
Control Processing:
Processing interval is 4 times per power
system cycle (except for math
variables and analog quantities, which
are processed every 25 ms). The 51
elements are processed 2 times per
power system cycle. Analog quantities
for rms data are determined through
use of data averaged over the previous
8 cycles.
Oscillography
Length:
15, 64, or 180 cycles
Sampling Rate:
32 samples per cycle unfiltered
4 samples per cycle filtered
Trigger:
Programmable with Boolean expression
Format:
ASCII and Compressed ASCII
Binary COMTRADE (32 samples/cycle
unfiltered)
Time-Stamp Resolution:
1 ms
Time-Stamp Accuracy:
±5 ms
Sequential Events Recorder
Time-Stamp Resolution:
1 ms
Time-Stamp Accuracy
(With Respect to Time
Source) for all Relay
Word bits except those
corresponding to digital
inputs (IN
xxx
): ±5
ms
Time-Stamp Accuracy
(With Respect to Time
Source) for Relay Word
bits corresponding to
digital inputs (IN
xxx
):
1 ms
Relay Elements
Instantaneous/Definite-Time Overcurrent (50P, 50G, 50N, 50Q)
Pickup Setting Range, A secondary
5 A Model:
0.50–96.00 A, 0.01 A steps
1 A Model:
0.10–19.20 A, 0.01 A steps
Accuracy:
±3% of setting plus ±0.02 • I
NOM
A
secondary (steady state)
±5% of setting plus ±0.02 • I
NOM
A
secondary (transient)
±6% of setting plus ±0.02 • I
NOM
A
secondary (transient for 50Q)
Time Delay:
0.00–5.00 seconds, 0.01-second steps
0.00–120.00 seconds, 0.01-second steps
(50Q)
±0.5% plus ±0.25 cycle
Pickup/Dropout Time:
<1.5 cycle
Inverse-Time Overcurrent (51P, 51G, 51N, 51Q)
Pickup Setting Range, A secondary
5 A Model:
0.50–16.00 A, 0.01 A steps
1 A Model:
0.10–3.20 A, 0.01 A steps
Accuracy:
±5% of setting plus ±0.02 • I
NOM
A
secondary (steady-state pickup)
Time Dial
U.S.:
0.50–15.00, 0.01 steps
IEC:
0.05–1.00, 0.01 steps
Accuracy:
±1.5 cycles plus ±4% between 2 and 30
multiples of pickup (within rated
range of current)
Differential (87)
Unrestrained Pickup
Range:
1.0–20.0 in per unit of TAP
Restrained Pickup Range:
0.10–1.00 in per unit of TAP
Pickup Accuracy (A secondary)
5 A Model:
±5% plus ±0.10 A
1 A Model:
±5% plus ±0.02 A
Unrestrained Element
Pickup Time:
0.8/1.0/1.9 cycles (Min/Typ/Max)
Restrained Element (With Harmonic Blocking)
Pickup Time:
1.5/1.6/2.2 cycles (Min/Typ/Max)
Restrained Element (With Harmonic Restraint)
Pickup Time:
2.62/2.72/2.86 cycles (Min/Typ/Max)
Harmonics
Pickup Range (% of
fundamental): 5%–100%
Pickup Accuracy (A secondary)
5 A Model:
±5% plus ±0.10 A
1 A Model:
±5% plus ±0.02 A
Time Delay Accuracy:
±0.5% plus ±0.25 cycle
Restricted Earth Fault (REF)
Pickup Range (per unit of
I
NOM
of neutral current
inputs, IN, and/or
Winding 3):
0.05–3.00 per unit, 0.01 per-unit steps
Pickup Accuracy (A secondary)
5 A Model:
±5% plus ±0.10 A
1 A Model:
±5% plus ±0.02 A
Timing Accuracy
Directional Output
Maximum Pickup/
Dropout Time:
1.75 cycles
ANSI Extremely Inverse
TOC Curve (U4 With
0.5 Time Dial):
±5 cycles plus ±5% between 2 and 30
multiples of pickup (within rated
range of current)
Undervoltage (27P, 27PP, 27S)
Setting Range:
OFF, 12.50–300.00 V (phase elements,
phase-to-phase elements with delta
inputs or synchronism voltage input)
OFF, 12.50–520.00 V (phase-to-phase
elements with wye inputs)
Accuracy:
±1% of setting plus ±0.5 V
Pickup/Dropout Time:
<1.5 cycle
Time Delay:
0.00–120.00 seconds, 0.01-second steps
Accuracy:
±0.5% plus ±0.25 cycle
Overvoltage (59P, 59PP, 59G, 59Q, 59S)
Setting Range:
OFF, 12.50–300.00 V (phase elements,
phase-to-phase elements with delta
inputs or synchronism voltage input)
OFF, 12.50–520.00 V (phase-to-phase
elements with wye inputs)
Accuracy:
±1% of setting plus ±0.5 V
Pickup/Dropout Time:
<1.5 cycle
Time Delay:
0.00–120.00 seconds, 0.01-second steps
Accuracy:
±0.5% plus ±0.25 cycle
