1.17
Date Code 20170927 Instruction Manual SEL-751 Relay
Introduction and Specifications
Specifications
Surge Immunity: IEC 61000-4-5:2005
IEC 60255-26:2013; Section 7.2.7
2 kV line-to-line
4 kV line-to-earth
Surge Withstand Capability
Immunity:
IEC 60255-26:2013; Section 7.2.6
EN 61000-4-18:2010
2.5 kV common mode
1 kV differential mode
1 kV common mode on comm. ports
IEEE C37.90.1-2002
2.5 kV oscillatory
4 kV fast transient
Environmental
Cold: IEC 60068-2-1:2007
Severity Level: 16 hours at –40°C
Damp Heat, Cyclic: IEC 60068-2-30:2005
Severity Level: 25°C to 55°, 6 cycles,
Relative Humidity: 95%
Damp Heat, Steady State: IEC 60068-2-78:2001
Severity Level: 93% RHMin, 40°C;
10 days
Dry Heat: IEC 60068-2-2:2007
Severity Level: 16 hours at +85°C
Enclosure Protection: IEC 60529:2001 + CRDG:2003
IP65 enclosed in panel (2-line display
models)
IP54 enclosed in panel (touchscreen
models)
IP20 for terminals
IP50 for terminals enclosed in the dust-
protection assembly (protection
against solid foreign objects only
(SEL Part #915900170). 10°C
temperature derating applies to the
temperature specifications of the relay.
Vibration Resistance: IEC 60255-21-1:1988
Endurance: Class 2
Response: Class 2
Shock Resistance: IEC 60255-21-2:1988
Withstand: Class 1
Response: Class 2
Bump: Class 1
Seismic Resistance: IEC 60255-21-3:1993
Quake Response: Class 2
Safety
Dielectric Test (Hi-Pot): IEC 60255-27:2013; Section 10.6.4.3
IEEE C37.90-2005
Severity Level: 2500 Vac on contact
inputs, contact outputs, and analog
inputs. 3100 Vdc on power supply.
Type Tested for 1 minute.
Impulse Voltage Test: IEC 60255-27:2013
Section 10.6.4.2 ac or dc
Severity Level: 0.5 J, 5 kV
IEEE C37.90:2005
Severity Level: 0.5 J, 5 kV
Processing Specifications and Oscillography
AC Voltage and
Current Inputs: 32 samples per power system cycle
Frequency Tracking Range: 15–70 Hz
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). Analog
quantities for rms data are derived
from data averaged from the previous
8 cycles
Arc-Flash Processing: Arc-Flash light is sampled 32 times per
cycle.
Arc-Flash current, light, and 2 fast
hybrid outputs are processed 16 times
per cycle.
Oscillography
Length: 15, 64, or 180 cycles
Sampling Rate: 16 samples per cycle unfiltered,
4 samples per cycle filtered
Trigger: Programmable with Boolean expression
Format: ASCII and Compressed ASCII
Binary COMTRADE (32 samples per
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): 5 ms
Relay Elements
Instantaneous/Definite-Time Overcurrent (50P, 50G, 50N, 50Q)
Pickup Setting Range, A Secondary:
5 A models: 0.25–100.00 A, 0.01 A steps
1 A models: 0.05–20.00 A, 0.01 A steps
200 mA model: 0.01–4.00 A, 0.01 A steps (50N)
Accuracy: ±3% plus ±0.02 • I
NOM
A secondary
(Steady State)
±5% plus ±0.02 • I
NOM
A secondary
(Transient)
±6% plus ±0.02 • I
NOM
A secondary
(Transient for 50Q)
Time Delay: 0.00–400.00 seconds, 0.01 seconds
steps
0.1–400.0 seconds, 0.1 second steps
(50Q)
Pickup/Dropout Time: <1.5 cycles
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