Date Code 20080213 Instruction Manual SEL-351A Relay
Preface
Manual Overview
The SEL-351A Instruction Manual describes common aspects of protection
relay application and use. It includes the necessary information to install, set,
test, and operate the relay and more detailed information about settings and
commands. The SEL-351A features include directional elements, load
encroachment, synchronism check, station batter monitor, and sensitive earth
fault functionality. The SEL-351A-1 model is a non-directional three-voltage
version of the SEL-351A. Throughout the manual, notes indicate where
features are not available in the SEL-351A-1.
An overview of each manual section and topics follows:
Preface. Describes the manual organization and conventions used to
present information.
Section 1: Introduction and Specifications. Describes the basic features
and functions of the SEL-351A; lists the relay specifications.
Section 2: Installation. Describes how to mount and wire the SEL-351A;
illustrates wiring connections for various applications; describes
operation of current board jumpers; and depicts relay front and rear
panels.
Section 3: Overcurrent, Voltage, Synchronism Check, and Frequency Ele-
ments.
Describes the operation of the instantaneous/definite-time
overcurrent elements (phase, neutral ground, residual ground, and
negative sequence); time-overcurrent elements (phase, neutral ground,
residual ground, and negative sequence); voltage elements (single
phase, phase to phase, etc.; synchronism check elements; and
frequency elements.
Section 4: Loss-of-Potential, Load Encroachment, and Directional Element
Logic.
Describes the operation of loss-of-potential logic and its effect on
directional elements; load-encroachment logic and its application to
phase overcurrent elements; voltage-polarized and current-polarized
directional elements, including directional control for low-impedance
grounded, Petersen Coil grounded, and ungrounded/high-impedance
grounded systems; Best Choice Ground Directional
™
logic and
automatic settings.
Section 5: Trip and Target Logic. Describes the operation of general trip
logic, switch-onto-fault trip logic, and front-panel target LEDs.
Section 6: Close and Reclose Logic. Describes the close logic operation
for automatic reclosures and other close conditions (e.g., manual close
initiation via serial port or optoisolated inputs).
Section 7: Inputs, Outputs, Timers, and Other Control Logic. Describes the
operation of optoisolated inputs IN101–IN106, local control switches
(local bit outputs LB1–LB16), remote control switches (remote bit
outputs RB1–RB16), latch control switches (latch bit outputs LT1–
LT16), multiple setting groups (six available), programmable timers
(timer outputs SV1T–SV16T), output contacts OUT101–OUT107 and
ALARM, and rotating default displays.
Courtesy of NationalSwitchgear.com
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