Schweitzer Engineering Laboratories SEL-251 - Section 7: Maintenance and Testing;Section 7: Maintenance and Testing

Date Code 20000421 Table of Contents i
SEL-251, -2, -3 Instruction Manual
TABLE OF CONTENTS
SECTION 7: MAINTENANCE AND TESTING 7-1
Test Procedures............................................................................................................................ 7-1
Test Aids Provided by the Relay.......................................................................................... 7-1
Low-Level Test Interface ..................................................................................................... 7-2
Test Methods........................................................................................................................ 7-2
Initial Checkout............................................................................................................................ 7-4
Equipment Required............................................................................................................. 7-4
Checkout Procedure.............................................................................................................. 7-4
Full Functional Test ................................................................................................................... 7-10
Equipment Required........................................................................................................... 7-10
What Should Be Tested...................................................................................................... 7-11
Setting Test......................................................................................................................... 7-11
Meter Test........................................................................................................................... 7-11
Overcurrent Element Pickup Tests..................................................................................... 7-13
Definite-Time Overcurrent Element Timing Tests ............................................................ 7-14
Time-Overcurrent Element Timing Tests .......................................................................... 7-15
Demand Ammeter Timing Tests ........................................................................................ 7-16
Reclosing Relay Tests Setup.............................................................................................. 7-17
Reclosing Relay Reset Interval Timer Test........................................................................ 7-19
Reclosing Relay Open Interval Timer Test........................................................................ 7-20
Reclosing Relay States Test ............................................................................................... 7-21
Reclosing Relay Shot Bit Test............................................................................................ 7-22
Reclosing Relay Sequence Coordination Test ................................................................... 7-23
Close Failure Timer Test.................................................................................................... 7-25
Trip Failure Timer Test...................................................................................................... 7-26
Input Circuits Test.............................................................................................................. 7-28
Serial Ports Test ................................................................................................................. 7-28
IRIG-B Time Code Input Test............................................................................................ 7-28
Power Supply Voltages Test .............................................................................................. 7-29
Relay Calibration........................................................................................................................ 7-29
Troubleshooting ......................................................................................................................... 7-29
Inspection Procedure.......................................................................................................... 7-29
Troubleshooting Table ....................................................................................................... 7-30
Firmware Upgrade Instructions.................................................................................................. 7-32
Upgrade Instructions .......................................................................................................... 7-32
Factory Assistance...................................................................................................................... 7-33
TABLES
Table 7.1: Fault Locator Test Values..................................................................................................... 7-10
Table 7.2: Current Quantities for 51NT Timing Test Example............................................................. 7-16
Table 7.3: Contact Inputs and Terminal Numbers................................................................................. 7-28