Date Code 20080918 Instruction Manual SEL-749M Relay
Section 4
Protection and Logic Functions
Instructi on Manual
Overview
This section describes the SEL-749M Relay settings, including the motor
protection elements and basic functions, control I/O logic, as well as the
settings that control the communications ports and front-panel displays.
See Section 6: Settings for settings hide rules and settings interdependency
checks. The settings are not case sensitive.
NOTE: Each SEL-749M is shipped
with factory-default settings.
Calculate the settings for your motor
to ensure secure and dependable
protection. Document and enter the
settings (see Section 6: Settings).
This section includes the following subsections:
Application Data. Lists information that you will need to know about the
protected motor before calculating the relay settings.
Main Settings. Lists settings that configure the relay inputs to accurately
measure and interpret the ac current and optional voltage input signals.
Basic Motor Protection. Lists settings for protection elements included in
all models of the SEL-749M, including the thermal element,
overcurrent elements, load-loss functions, and load-jam functions.
PTC and RTD-Based Protection. Lists settings associated with the PTC and
RTD inputs. You can skip this subsection if your application does not
include PTC and RTD inputs.
Voltage-Based Protection (Relays With Voltage Inputs). Lists settings
associated with the optional ac voltage-based protection elements. You
can skip this subsection if your relay is not equipped with optional
voltage inputs.
Frequency and Load Control Settings. Lists settings included in all models
of the SEL-749M with enhanced and/or expanded performance when
optional voltage inputs are used.
I/O Configuration. Lists inputs/output configuration settings including
Analog Output, Trip Inhibit, Trip/Close logic and Motor Control logic.
Logic Settings. Lists settings associated with latches, timers, and output
contacts.
Global Settings. Lists settings that allow you to configure the relay to your
power system, date format, and logic equations of global nature.
Serial Port Settings. Lists settings that configure the relay front- and rear-
panel serial ports.
Front Panel Settings. Lists settings for the front-panel display and LED
control.
Courtesy of NationalSwitchgear.com
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