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Date Code 20081022
Instruction Manual
SEL-787 Relay
Section 1
Introduction and Specifications
Instructi on Manual
Overview
The SEL-787 Transformer Protection Relay is designed to provide current
differential and overcurrent protection to two-winding transformers, buses,
generators, etc. The basic relay provides current differential and instantaneous
and inverse time-overcurrent protection. Voltage-based and RTD-based
protection are available as options. All relay models provide monitoring
functions.
This manual contains the information needed to install, set, test, operate, and
maintain any SEL-787. You need not review the entire manual to perform
specific tasks.
Features
Standard
Protection Features
➤
Phase Instantaneous Overcurrent (50P)
➤
Ground (Residual) Instantaneous Overcurrent (50G)
➤
Negative-Sequence Overcurrent (50Q)
➤
Phase Time Overcurrent (51P)
➤
Ground (Residual) Time Overcurrent (51G)
➤
Negative-Sequence Time Overcurrent (51Q)
➤
Current Differential (87)
➤
Breaker Failure Protection
Optional
Protection Features
➤
Voltage-Based Protection
➢
Undervoltage (27)
➢
Overvoltage (59)
➢
Negative-Sequence Overvoltage (59Q)
➢
Directional Power (32)
➢
Loss of Potential (60LOP)
➢
Frequency (81)
➢
Volts/Hertz (24)
➤
Neutral Current-Based Protection
➢
Neutral Instantaneous Overcurrent (50N)
➢
Neutral Time Overcurrent (51N)
➢
Restricted Earth Fault (REF)
Summary of Contents for SEL-787
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