Introduction and Specifications 1.

17
Specifications

Cold: IEC 60068-2-1:2007 Conducted RF Immunity: IEC 61000-4-6:2008

IEC 60255-27:2013, Section 10.6.1.2 IEC 60255-26:2013; Section 7.2.8
IEC 60255-27:2013, Section 10.6.1.4 10 Vrms
–40°C, 16 hours Magnetic Field Immunity: IEC 61000-4-8:2009
Dry Heat: IEC 60068-2-2:2007 IEC 60255-26:2013, Section 7.2.10
IEC 60255-27:2013, Section 10.6.1.1 Severity Level:
IEC 60255-27:2013, Section 10.6.1.3 1000 A/m for 3 seconds
85°C, 16 hours 100 A/m for 1 minute; 50/60 Hz
IEC 61000-4-9: 2001
Damp Heat, Steady State: IEC 60068-2-78:2001 Severity Level: 1000 A/m
IEC 60255-27:2013, Section 10.6.1.5 IEC 61000-4-10:2001
40°C, 93% relative humidity, 10 days Severity Level: 100 A/m
Damp Heat, Cyclic: IEC 60068-2-30:2001 (100 kHz and 1 MHz)
IEC 60255-27:2013, Section 10.6.1.6 Power Supply Immunity: IEC 61000-4-11:2004
25° to 55°C, 95% relative humidity, IEC 61000-4-17:1999
6 cycles IEC 61000-4-29:2000
Change of Temperature: IEC 60068-2-14:2009 IEC 60255-26:2013, Section 7.2.11
IEC 60255-1:2010, Section 6.12.3.5 IEC 60255-26:2013, Section 7.2.12
–40° to +85°C, ramp rate 1°C/min, IEC 60255-26:2013, Section 7.2.13
5 cycles
EMC Emissions

Dielectric Strength and Impulse Tests Conducted Emissions: IEC 60255-26:2013 Class A
FCC 47 CFR Part 15.107 Class A
Dielectric (Hi-Pot): IEC 60255-27:2013, Section 10.6.4.3 ICES-003 Issue 6
IEEE C37.90-2005 EN 55011:2009 + A1:2010 Class A
1.0 kVac on analog outputs, Ethernet EN 55022:2010 + AC:2011 Class A
ports EN 55032:2012 + AC:2013 Class A
2.0 kVac on analog inputs, IRIG CISPR 11:2009 + A1:2010 Class A
2.5 kVac on contact I/O CISPR 22:2008 Class A
3.6 kVdc on power supply, IN and VN CISPR 32:2015 Class A
terminals
Radiated Emissions: IEC 60255-26:2013 Class A
Impulse: IEC 60255-27:2013, Section 10.6.4.2 FCC 47 CFR Part 15.109 Class A
0.5 J, 5 kV on power supply, contact ICES-003 Issue 6
I/O, ac current, and voltage inputs EN 55011:2009 + A1:2010 Class A
0.5 J, 530 V on analog outputs EN 55022:2010 + AC:2011 Class A
IEEE C37.90:2005 EN 55032:2012 + AC:2013 Class A
0.5 J, 5 kV CISPR 11:2009 + A1:2010 Class A
0.5 J, 530 V on analog outputs CISPR 22:2008 Class A
CISPR 32:2015 Class A
RFI and Interference Tests
Electrostatic Discharge IEC 61000-4-2:2008 Processing Specifications and Oscillography
Immunity: IEC 60255-26:2013; Section 7.2.3 AC Voltage and
IEEE C37.90.3:2001 Current Inputs: 32 samples per power system cycle
Severity Level 4
Frequency Tracking Range: 15–70 Hz
8 kV contact discharge
15 kV air discharge Digital Filtering: One-cycle cosine after low-pass analog
filtering. Net filtering (analog plus
Radiated RF Immunity: IEC 61000-4-3:2010
digital) rejects dc and all harmonics
IEC 60255-26:2013; Section 7.2.4
greater than the fundamental.
10 V/m
IEEE C37.90.2-2004 Protection and Processing interval is 4 times per power
20 V/m Control Processing: system cycle (except for math
Fast Transient, Burst IEC 61000-4-4:2011 variables and analog quantities, which
Immunitya: IEC 60255-26:2013; Section 7.2.5 are processed every 25 ms). Analog
4 kV @ 5.0 kHz quantities for rms data are derived
2 kV @ 5.0 kHz for comm. ports from data averaged from the previous
8 cycles.
Surge Immunitya: IEC 61000-4-5:2005
IEC 60255-26:2013; Section 7.2.7 Arc-Flash Processing: Arc-Flash light is sampled 32 times per
2 kV line-to-line cycle
4 kV line-to-earth Arc-Flash current, light, and 2 fast
hybrid outputs are processed 16 times
Surge Withstand Capability EN 61000-4-18:2010
per cycle
Immunitya: IEC 60255-26:2013; Section 7.2.6
2.5 kV common mode
1 kV differential mode Oscillography
1 kV common mode on comm. ports Length: 15, 64, or 180 cycles
IEEE C37.90.1-2002
Sampling Rate: 16 samples per cycle unfiltered
2.5 kV oscillatory
4 samples per cycle filtered
4 kV fast transient
Trigger: Programmable with Boolean expression

Date Code 20210104 Instruction Manual SEL-751 Relay

 1.18 Introduction and Specifications
Specifications

Format: ASCII and Compressed ASCII Time Dial

Binary COMTRADE (32 samples per U.S.: 0.50–15.00, 0.01 steps
cycle unfiltered)
IEC: 0.01–1.50, 0.01 steps
Time-Stamp Resolution: 1 ms
Accuracy: ±1.5 cycles, plus ±4% between 2 and 30
Time-Stamp Accuracy: ±5 ms multiples of pickup (within rated
range of current)
Sequential Events Recorder
Time-Stamp Resolution: 1 ms IEC Thermal Element (49IEC)
Time-Stamp Accuracy (With Setting Range: Trip pickup, 1%–150%
Respect to Time Source) for Alarm pickup, 1%–100%
all Relay Word bits except
those corresponding to Pickup Accuracy: ±2% (for I ≥ INOM)
digital inputs (INxxx) and ±5% (for 0.4 • INOM < I < INOM)
arc-flash elements Time to Trip/Reset Accuracy: ±5% plus ±0.5 s of the calculated value
(TOLx/50xAF/OUTxxx): ±5 ms
Time-Stamp Accuracy (With Undervoltage (27P, 27PP, 27S)
Respect to Time Source) for
Setting Range: OFF, 2.00–300.00 V (phase elements,
Relay Word bits
corresponding to digital phase-to-phase elements with delta
inputs (INxxx) and arc-flash inputs or synchronism voltage input)
elements (TOLx/50xAF/ OFF, 2.00–520.00 V (phase-to-phase
OUTxxx): 1 ms elements with wye inputs)
Accuracy: ±1% of setting plus ±0.5 V
Relay Elements
Time Delay: 0.00–120.00 seconds, 0.01-second steps
Instantaneous/Definite-Time Overcurrent (50P, 50G, 50N, 50Q) Pickup/Dropout Time: <1.5 cycles
Pickup Setting Range, A Secondary:
Overvoltage (59P, 59PP, 59G, 59Q, 59S)
5 A models: 0.25–100.00 A, 0.01 A steps
Setting Range: OFF, 2.00–300.00 V (phase elements,
1 A models: 0.05–20.00 A, 0.01 A steps phase-to-phase elements with delta
200 mA model: 0.01–4.00 A, 0.01 A steps (50N) inputs or synchronism voltage input)
OFF, 2.00–520.00 V (phase-to-phase
Accuracy: ±3% of setting plus ±0.02 • INOM A
elements with wye inputs)
secondary (steady state)
±5% of setting plus ±0.02 • INOM A Accuracy: ±1% of setting plus ±0.5 V
secondary (transient) Time Delay: 0.00–120.00 seconds, 0.01-second steps
±6% of setting plus ±0.02 • INOM A
Pickup/Dropout Time: <1.5 cycles
secondary (transient for 50Q)
Time Delay: 0.00–400.00 seconds, 0.01 seconds Inverse-Time Undervoltage (27I)
steps
Setting Range: OFF, 2.00–300.00 V (phase elements,
Pickup/Dropout Time: <1.5 cycles positive-sequence elements, phase-to-
phase elements with delta inputs or
Arc-Flash Instantaneous Overcurrent (50PAF, 50NAF) synchronism-check voltage input)
Pickup Setting Range, A Secondary: OFF, 2.00–520.00 V (phase-to-phase
elements with wye inputs)
5 A models: 0.50–100.00 A, 0.01-A steps
Accuracy: ±1% of setting plus ±0.5 V
1 A models: 0.10–20.00 A, 0.01 A-steps
Time Dial: 0.00–16.00 s
Accuracy: 0 to +10% of setting plus ±0.02 • INOM
A secondary (steady state pickup) Accuracy: ±1.5 cyc plus ±4% between 0.95 and
0.1 multiples of pickup
Pickup/Dropout Time: 2–5 ms/1 cycle

Arc-Flash Time-Overlight (TOL1–TOL8) Inverse-Time Overvoltage (59I)

Setting Range: OFF, 2.00–300.00 V (phase elements,
Pickup Setting Range, % of 3.0–80.0% (point sensor)
Full Scale: sequence elements, or phase-to-phase
0.6–80.0% (fiber sensor)
elements with delta inputs or
Pickup/Dropout Time: 2–5 ms/1 cycle synchronism voltage input)
OFF, 2.00–520.00 V (phase-to-phase
Inverse-Time Overcurrent (51P, 51G, 51N, 51Q) elements with wye inputs)
Pickup Setting Range, A Secondary: Accuracy: ±1% of setting plus ±0.5 V
5 A models: 0.25–24.00 A, 0.01 A steps Time Dial: 0.00–16.00 s
1 A models: 0.05–4.80 A, 0.01 A steps Accuracy: ±1.5 cyc plus ±4% between 1.05 and
200 mA models: 10.00–960.00 mA, 0.01 mA steps (51N) 5.5 multiples of pickup
Accuracy: ±5% of setting plus ±0.02 • INOM A
secondary (steady state pickup)

SEL-751 Relay Instruction Manual Date Code 20210104

 Introduction and Specifications 1.19
Specifications

Slip Frequency Pickup

Harmonic Blocking Accuracy: ±0.02 Hz
Pickup Range (% of Phase Angle Range: 0°–80°
fundamental): 5%–100%
Phase Angle Accuracy: ±4°
Pickup Accuracy (A secondary):
5 A models: ±5% plus ±0.10 A of harmonic current Load-Encroachment Detection
1 A models: ±5% plus ±0.02 A of harmonic current Pickup Setting Range
Time Delay Accuracy: ±0.5% plus ±0.25 cycle 5 A Model: 0.10–128.00 Ω secondary,
0.01 Ω steps
Vector Shift (78VS) 1 A Model: 0.50–640.00 Ω secondary,
Pickup Setting Range: 2.0°–30.0°, 0.1-degree increment 0.01 Ω steps
Accuracy: ±10% of the pickup setting, ±1 degree Forward Load Angle: –90° to +90°
Voltage Supervision 20.0%–100.0% • VNOM Forward Load Angle: +90° to +270°
Threshold:
Accuracy
Pickup Time: <3 cycles
Impedance Measurement: ±5% plus ±0.5 Ω
Power Elements (32) Angle Measurement: ±3°
Instantaneous/Definite Time, +W, –W, +VAR, –VAR
Three-Phase Elements Type: Station Battery Voltage Monitor
Pickup Setting Range, VA Secondary: Operating Range: 0–350 Vdc (300 Vdc for UL purposes)
5 A models: 1.0–6500.0 VA, 0.1 VA steps Pickup Range: 20.00–300.00 Vdc
1 A models: 0.2–1300.0 VA, 0.1 VA steps Pickup accuracy: ±2% of setting plus ±2 Vdc
Accuracy: ±0.10 A • (L-L voltage secondary) plus
±5% of setting at unity power factor
Timers
for power elements and zero power Setting Range: Various
factor for reactive power elements Accuracy: ±0.5% of setting plus ±1/4 cycle
(5 A nominal)
±0.02 A • (L-L voltage secondary) plus RTD Protection
±5% of setting at unity power factor
for power elements and zero power Setting Range: Off, 1°–250°C
factor for reactive power elements Accuracy: ±2°C
(1 A nominal) RTD Open-Circuit Detection: >250°C
Time Delay: 0.0–240.0 seconds, 0.1-second steps RTD Short-Circuit Detection: <–50°C
Pickup/Dropout Time: <10 cycles RTD Types: PT100, NI100, NI120, CU10
RTD Lead Resistance: 25 Ω max. per lead
Power Factor (55)
Update Rate: <3 s
Setting Range: OFF, 0.05–0.99
Noise Immunity on RTD As high as 1.4 Vac (peak) at 50 Hz or
Accuracy: ±5% of full scale
Inputs: greater frequency
for current ≥ 0.5 • INOM
RTD Fault/Alarm/Trip Time Approx. 12 s
Time Delay: 1–240 seconds, 1-second steps
Delay:

Frequency (81) Metering

Setting Range: Off, 15.00–70.00 Hz
Accuracies are specified at 20°C, nominal frequency, ac currents within
Accuracy: ±0.01 Hz (V1 >60 V) with voltage (0.2–20.0) • INOM A secondary, and ac voltages within 50–250 V
tracking secondary (1.33–6.67 V secondary with 8 V LEA option), unless
±0.05 Hz (I1 >0.8 • INOM) with current otherwise noted.
tracking Phase Currents: ±1% of reading, ±1° (±2.5° at 0.2–0.5 A
Time Delay: 0.00–400.00 seconds, 0.01-second steps for relays with INOM = 1 A)
Pickup/Dropout Time: <4 cycles Three-Phase Average Current: ±1% of reading
IG (Residual Current): ±2% of reading, ±2° (±5.0° at 0.2–0.5 A
Rate-of-Change of Frequency (81R) for relays with INOM = 1 A)
Setting Range: OFF, 0.10–15.00 Hz/s IN (Neutral Current): ±1% of reading, ±1° (±2.5° at 0.2–0.5 A
Accuracy: ±100 mHz/s, plus ±3.33% of pickup for relays with INOM = 1 A)
±1.6 mA and ±1% (0.04–4.0 A) (0.2 A
Time Delay: 0.10–60.00 seconds, 0.01-second steps nominal channel IN current input)

Synchronism Check (25) I1 Positive-Sequence Current: ±2% of reading

3I2 Negative-Sequence
Pickup Range, Secondary
Current: ±2% of reading
Voltage: 0.00–300.00 V
System Frequency: ±0.01 Hz of reading for frequencies
Pickup Accuracy, Secondary ±1% plus ±0.5 V
Voltage: within 15–70 Hz (V1 > 60 V)
(over the range of 2–300 V)
Line-to-Line Voltages: ±1% of reading, ±1° for voltages
Slip Frequency Pickup Range: 0.05 Hz–0.50 Hz

Date Code 20210104 Instruction Manual SEL-751 Relay

 1.20 Introduction and Specifications
Specifications

Three-Phase Average ±1% of reading for voltages within

Line-to-Line Voltage: 24–264 V Accuracy for Voltages
Line-to-Ground Voltages: ±1% of reading, ±1° for voltages within Level 1 compliant as specified in IEEE C37.118 under the following
24–264 V (0.64–7.04 V for LEA conditions for the specified range.
inputs) Conditions
Three-Phase Average ±1% of reading for voltages within ➤ At maximum message rate
Line-to-Ground Voltages: 24–264 V (0.64–7.04 V for LEA ➤ When phasor has the same frequency as the positive-sequence
inputs) voltage
Voltage Imbalance (%): ±2% of reading ➤ Frequency-based phasor compensation is enabled PHCOMP := Y)
➤ The narrow bandwidth filter is selected (PMAPP := N)
V1 Positive-Sequence ±2% of reading for voltages within
Voltage: 24–264 V (0.64–7.04 V for LEA Range
inputs) Frequency: ±5.0 Hz of nominal (50 or 60 Hz)
3V2 Negative-Sequence ±2% of reading for voltages within Magnitude: 30 V–250 V
Voltage: 24–264 V (0.64–7.04 V for LEA
Phase Angle: –179.99° to 180.00°
inputs)
Out-of-Band Interfering
Real Three-Phase Power Frequency (Fs): 10 Hz ≤ Fs ≤ (2 • FNOM)
(kW): ±3% of reading for 0.10 < pf < 1.00
Reactive Three-Phase Power Accuracy for Currents
(kVAR): ±3% of reading for 0.00 < pf < 0.90
Level 1 compliant as specified in IEEE C37.118 under the following
Apparent Three-Phase Power conditions for the specified range.
(kVA): ±3% of reading
Conditions
Power Factor: ±2% of reading
➤ At maximum message rate
RTD Temperatures: ±2°C
➤ When phasor has the same frequency as the positive-sequence
voltage
Energy Meter ➤ Frequency-based phasor compensation is enabled
Accumulators: Separate IN and OUT accumulators (PHCOMP := Y)
➤ The narrow bandwidth filter is selected (PMAPP := N)
updated once per second, transferred
to nonvolatile storage 4 times per day Range
ASCII Report Resolution: 0.001 MWh Frequency: ±5.0 Hz of nominal (50 or 60 Hz)
Accuracy: The accuracy of the energy meter Magnitude: (0.4–2) • INOM (INOM = 1 A or 5 A)
depends on applied current and power
Phase Angle: –179.99° to 180.00°
factor as shown in the power metering
accuracy specifications above. The Out-of-Band Interfering
additional error introduced by Frequency (Fs): 10 Hz ≤ Fs ≤ (2 • FNOM)
accumulating power to yield energy is a Front port serial cable (non-fiber) lengths assumed to be <3 m.
negligible when power changes slowly
compared to the processing rate of
once per second.

Synchrophasor Accuracy
Maximum Message Rate
Nominal 60 Hz System: 60 messages per second
Nominal 50 Hz System: 50 messages per second
The voltage accuracy specifications are only applicable for the model
options with standard voltage inputs (not applicable to LEA option).
The current accuracy specifications are applicable for all 1 A and 5 A
options.
Note: For the SEL-751 current only model, the accuracy specifications
for currents are only applicable when the applied signal frequency
equals FNOM.

SEL-751 Relay Instruction Manual Date Code 20210104