Date Code 20100129
Instruction Manual
SEL-751A Relay
Section 4
Protection and Logic Functions
Overview
NOTE:
Each SEL-751A is shipped
with default factory settings. Calculate
the settings for your application to
ensure secure and dependable
protection. Document and enter the
settings (see
This section describes the SEL-751A Feeder Protection Relay settings,
including the protection elements and basic functions, control I/O logic, as
well as the settings that control the communications ports and front-panel
displays.
This section includes the following subsections:
Lists information that you will need to know about the
protected equipment before calculating the relay settings.
.
Lists settings that configure the relay
inputs to accurately measure and interpret the ac current and optional
voltage input signals.
Lists settings for protection elements included in all
models of the SEL-751A, including the overcurrent elements.
.
Lists settings associated with the RTD inputs. You
can skip this subsection if your application does not include RTD
inputs.
.
Lists settings associated with undervoltage,
overvoltage, power factor, and synchronism-check elements. These
elements are available when an optional voltage input card is present.
You can skip this subsection if your relay is not equipped with optional
voltage inputs.
.
Lists settings included in all models of the
SEL-751A with enhanced and/or expanded performance when
optional voltage inputs are used.
.
Lists Trip and Close logic.
.
Describes the logic that supervises automatic
reclosing when an open interval time times out—a final condition
check right before the close logic asserts the close output contact.
Describes all the reclosing relay settings and logic needed
for automatic reclosing (besides the final close logic and reclose
supervision logic described previously).
Lists settings associated with demand metering.
Logic Settings (SET L Command)
.
Lists settings associated with latches,
timers, and output contacts.
Global Settings (SET G Command)
.
Lists settings that allow you to configure
the relay to your power system, date format, analog inputs/outputs, and
logic equations of global nature.
Summary of Contents for 751A
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