Schweitzer Engineering Laboratories SEL-751 - Overview

Date Code 20170927 Instruction Manual SEL-751 Relay
Section 4
Protection and Logic Functions
Overview
This section describes the SEL-751 Feeder Protection Relay settings, includ-
ing the protection elements and basic functions, control I/O logic, as well as the set-
tings that control the communications ports and front-panel displays.
This section includes the following subsections:
Application Data. Lists information that you need to know about the
protected equipment before calculating the relay settings. Lists the
settings for protection elements included in all models of the SEL-751.
Group Settings (SET Command).
ID Settings and Configuration Settings.
Lists the ID settings and the
settings that configure the relay inputs to accurately measure and
interpret the ac current and voltage input signals.
Low-Energy Analog (LEA) Voltage Inputs. Discusses the settings
associated with LEA voltage inputs.
Overcurrent Elements. Lists the settings associated with overcurrent,
time-overcurrent and directional elements.
High-Impedance Fault Detection With Arc Sense Technology. Lists the
settings associated with high-impedance fault detection.
Second- and Fifth-Harmonic Blocking Logic. Lists the settings associated
with second- and fifth-harmonic blocking logic.
RTD-Based Protection. Lists the settings associated with the RTD inputs.
You can skip this subsection if your application does not include RTD
inputs.
IEC Thermal Elements. Lists the settings associated with IEC thermal
elements.
Under- and Overvoltage Functions. Lists the settings associated with the
under- and overvoltage elements.
Synchronism-Check Elements. Lists the settings associated with
synchronism-check elements.
Power Elements. Lists the settings associated with power elements.
Power Factor Elements. Lists the settings associated with power factor
elements.
Loss-of-Potential (LOP) Protection. Lists the logic and settings associated
with the LOP element.
Vector Shift Element. Lists the settings associated with vector shift logic.
NOTE: Each SEL-751 is shipped with
default factory settings. Calculate the
settings for your application to
ensure secure and dependable
protection. Document and enter the
settings (see Section 6: Settings).