Schweitzer Engineering Laboratories SEL-251 - Table of Contents

Date Code 20000421 Specifications i
SEL-251, -2, -3 Instruction Manual
TABLE OF CONTENTS
SECTION 2: SPECIFICATIONS 2-1
General Specifications ................................................................................................................. 2-1
Functional Specifications............................................................................................................. 2-7
Phase Overcurrent Elements for Phase and Three-Phase Faults - See Figure 2.18 and
Figure 2.21.................................................................................................................... 2-7
Negative-Sequence Overcurrent Elements for Phase-to-Phase Faults - See
Figure 2.19.................................................................................................................... 2-7
Ground/Residual Overcurrent Elements for Ground Faults - See Figure 2.20 .................... 2-8
Voltage Element for Healthy/Low Voltage Indication or Internal Control (27) - See
Figure 2.21.................................................................................................................... 2-8
Time Delayed 52A or 52B Functions Handle Fuse-Saving and Inrush ............................... 2-8
Trip Failure Timer Detects Breaker Failure or Slow Trip - See Figure 2.24....................... 2-9
Close Failure Timer Detects Failure to Close or Slow Close - See Figure 2.25................. 2-9
Trip Circuit Monitor Alarm Checks Trip Circuit and Verifies Circuit Breaker Status
Input.............................................................................................................................. 2-9
SEL-251 Relay SELOGIC
®
Control Equations........................................................................... 2-10
Assign Inputs to the Functions You Need.......................................................................... 2-11
Select Combinations of Relay Elements for Tripping and Other Purposes....................... 2-13
Time Delayed Variables ST, KT, and ZT.......................................................................... 2-15
Use !L for Inversion ........................................................................................................... 2-16
Programming Output Contacts........................................................................................... 2-16
Viewing Logic Equations................................................................................................... 2-16
SELOGIC Control Equations Settings in Each Setting Group............................................ 2-17
Targets........................................................................................................................................ 2-17
Multiple Shot Reclosing Relay .................................................................................................. 2-17
Reclose Cancel Conditions................................................................................................. 2-18
Sequence Coordination....................................................................................................... 2-19
Selectable Setting Groups .......................................................................................................... 2-20
Circuit Breaker Monitor............................................................................................................. 2-22
Metering ..................................................................................................................................... 2-22
Serial Interfaces.......................................................................................................................... 2-22
Self-Tests.................................................................................................................................... 2-23
Offset.................................................................................................................................. 2-23
Power Supply...................................................................................................................... 2-23
Random-Access Memory ................................................................................................... 2-23
Read-Only Memory............................................................................................................ 2-24
Analog-to-Digital Converter............................................................................................... 2-24
Master Offset...................................................................................................................... 2-24
Settings............................................................................................................................... 2-24
IRIG-B Input Description........................................................................................................... 2-25
Signal Processing ....................................................................................................................... 2-25
Torque Control........................................................................................................................... 2-26
External Torque Control..................................................................................................... 2-26
Internal Torque Control...................................................................................................... 2-27