1.21
Date Code 20100129 Instruction Manual SEL-751A Relay
Introduction and Specifications
Specifications
Fast Hybrid (High-Speed, High-Current Interrupting)
Make: 30 A
Carry: 6 A continuous carry at 70°C
4 A continuous carry at 85°C
1 s Rating: 50 A
MOV Protection (maximum
voltage): 250 Vac/330 Vdc
Pickup Time: < 50 μs, resistive load
Dropout Time: < 8 ms, resistive load
Break Capacity (10000 Operations):
48 Vdc 10.0 A L/R = 40 ms
125 Vdc 10.0 A L/R = 40 ms
250 Vdc 10.0 A L/R = 20 ms
Cyclic Capacity (4 cycles in 1 second, followed by 2 minutes idle for
thermal dissipation):
48 Vdc 10.0 A L/R = 40 ms
125 Vdc 10.0 A L/R = 40 ms
250 Vdc 10.0 A L/R = 20 ms
Note: Per IEC 60255-23:1994, using the simplified method of
assessment.
Note: Make rating per IEEE C37.90-1989.
Optoisolated Control Inputs
When Used With DC Control Signals
250 V: ON for 200–275 Vdc
OFF below 150 Vdc
220 V: ON for 176–242 Vdc
OFF below 132 Vdc
125 V: ON for 100–135.5 Vdc
OFF below 75 Vdc
110 V: ON for 88–121 Vdc
OFF below 66 Vdc
48 V: ON for 38.4–52.8 Vdc
OFF below 28.8 Vdc
24 V: ON for 15–30 Vdc
OFF for <5 Vdc
When Used With AC Control Signals
250 V: ON for 170.6–300 Vac
OFF below 106 Vac
220 V: ON for 150.2–264 Vac
OFF below 93.3 Vac
125 V: ON for 85–150 Vac
OFF below 53 Vac
110 V: ON for 75.1–132 Vac
OFF below 46.6 Vac
48 V: ON for 32.8–60 Vac
OFF below 20.3 Vac
24 V: ON for 14–27 Vac
OFF below 5 Vac
Current Draw at
Nominal DC Voltage:
2 mA (at 220–250 V)
4 mA (at 48–125 V)
10 mA (at 24 V)
Rated Impulse Withstand
Voltage (U
imp
): 4000 V
UL/CSA Digital Output Contact Temperature Derating for Operating at
Elevated Temperatures
Digital Output
Cards Installed
Operating
Ambient
Maximum Value
of Current (I
the
) Duty Factor
1–3 less than or equal
to 60°C
5.0 A Continuous
1–3 between 60°C and
70°C
2.5 A Continuous
Analog Output (Optional)
1A0 4A0
Current: 4–20 mA ±20 mA
Voltage: — ±10 V
Load at 1 mA: — 0–15 kΩ
Load at 20 mA: 0–300 Ω 0–750 Ω
Load at 10 V: — >2000 Ω
Refresh Rate: 100 ms
Error: < ±0.55%, Full Scale, at 25°C
Select From: Analog quantities available in the relay
Analog Inputs (Optional)
Maximum Input Range: ±20 mA
±10 V
Operational range set by user
Input Impedance: 200 Ω (current mode)
>10 kΩ (voltage mode)
Accuracy at 25°C:
With User Calibration: 0.050% of ±20 mA (current mode)
0.025% of ±10 V (voltage mode)
Without User Calibration: 0.050% of ±20 mA (current mode)
0.25% of ±10 V (voltage mode)
Accuracy Variation With
Temperature: ±0.015% per °C of full-scale
(±20 mA or ±10 V)
Arc-Flash Detectors (Optional)
Multimode fiber-optic receiver/transmitter pair
Fiber Type: 1000 µm diameter, 640 nm wavelength,
plastic, bare, or jacketed
Connector Type: V-Pin
Laser/LED: Class 1 LED, complies with
IEC 60825 1:1993 + A1:1997
+ A2:2001
Frequency and Phase Rotation
System Frequency: 50, 60 Hz
Phase Rotation: ABC, ACB
Frequency Tracking: 20–70 Hz
Time-Code Input
Format: Demodulated IRIG-B
On (1) State: V
ih
≥2.2 V
Off (0) State: V
il
≤0.8 V
Input Impedance: 2 kΩ
Accuracy: Relay time is synchronized to within
±5 ms of time-source input.
Communications Ports
Standard EIA-232 (2 ports)
Location: Front Panel
Rear Panel
Data Speed: 300–38400 bps
EIA-485 Port (optional)
Location: Rear Panel
Data Speed: 300–19200 bps
Ethernet Port (optional)
Single/Dual 10/100BASE-T copper (RJ-45 connector)
Single/Dual 100BASE-FX (LC connector)
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