Date Code 20170927 Instruction Manual SEL-751 Relay
Section 1
Introduction and Specifications
Overview
The SEL-751 Feeder Protection Relay provides a comprehensive combination
of protection, fault-locating features, monitoring, control, and communication
in an industrial package. The base relay includes current, voltage, frequency,
and power protection elements. Arc-flash detector-based, RTD-based,
directional control-based, and high-impedance-based fault detection
protection are available as options.
This manual contains the information necessary to install, set, test, operate,
and maintain any SEL-751. You need not review the entire manual to perform
specific tasks.
Features
Protection Features
The SEL-751 protection features depend on the model selected. The models
are configured with specific current/voltages input cards. The current/voltage
inputs cards are located in Slot Z and Slot E in the relay.
Slot Z cards are assigned a two-digit code beginning with the number “8” (for
300 Vac phase voltage inputs), with the letter “L” (for 8 Vac LEA phase
voltage inputs), or with the letter “A” (for no ac voltage inputs). The second
number represents the phase and neutral CT ratings in the SEL-751 two-line
and touchscreen display Model Options Tables (MOT, see Models, Options,
and Accessories). For example, “81” in the MOT for Slot Z indicates a
SEL
ECT 4 ACI/3 AVI card with three-phase ac current inputs (1 A nominal),
neutral ac current input (1 A nominal), and three-phase ac voltage inputs
(300 Vac).
Slot E cards are assigned a two-digit code beginning with the number “7” (for
300 Vac voltage inputs) or the letter “L” (for 8 Vac LEA phase voltage inputs)
in the SEL-751 two-line and touchscreen display Model Options Tables
(MOT). For example, “70” in the MOT for Slot E indicates a SEL
ECT 2AVI/
4 AFDI card with Vsyc (300 Vac), Vbat (300 V) input, and 4 arc-flash
detection inputs.
Table 1.1 shows the phase and neutral current ratings choices for the different
SEL-751 MOT choices. Phase current inputs are 1 A or 5 A nominal rating
and neutral current inputs are 1 A, 5 A, or 200 mA nominal rating.
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