Schweitzer Engineering Laboratories SEL-321 - Section 7: Maintenance and Testing

Date Code 20011026 Maintenance and Testing i
SEL-321/321-1 Instruction Manual
TABLE OF CONTENTS
SECTION 7: MAINTENANCE AND TESTING.......................................7-1
Introduction...................................................................................................................................7-1
Initial Checkout.............................................................................................................................7-1
Equipment Required .............................................................................................................7-1
Checkout Procedure..............................................................................................................7-1
Output Contact Explanation..................................................................................................7-6
Target LED Explanation.......................................................................................................7-7
Front Panel LCD Explanation............................................................................................... 7-7
Testing Philosophy .......................................................................................................................7-7
Acceptance Testing............................................................................................................... 7-8
Commissioning Testing ........................................................................................................7-8
Maintenance Testing.............................................................................................................7-9
Testing Methods and Tools ........................................................................................................7-10
Test Aids Provided by the Relay ........................................................................................7-10
Test Methods.......................................................................................................................7-10
Testing Via Front Panel LCD/LED Indication ........................................................... 7-11
Testing Via Output Contact Assertion........................................................................ 7-11
Using a Breaker Simulator ..........................................................................................7-12
Low-Level Test Interface.................................................................................................... 7-12
Test Setup ...................................................................................................................................7-13
Test Source Connections ....................................................................................................7-13
Three Voltage Source and Three Current Source Connections..................................7-13
Three Voltage Source and Two Current Source Connections ....................................7-14
Three Voltage Source and One Current Source Connections.....................................7-16
Serial Communication Equipment Connections................................................................. 7-17
Test Procedures...........................................................................................................................7-17
Overcurrent Elements .........................................................................................................7-17
Calculating Overcurrent Element Test Quantities ......................................................7-18
Overcurrent Element Test Examples ..........................................................................7-19
Single-Phase Overcurrent Element: 50H ...................................................................7-19
Phase-to-Phase Overcurrent Element: 50PP2 ............................................................7-20
Negative-Sequence Directional Element ............................................................................ 7-21
Negative-Sequence Directional Element Based Upon Negative-Sequence
Impedance ...........................................................................................................7-21
Negative-Sequence Directional Element Supervisory Conditions .............................7-23
Magnitude of 3I
2
..................................................................................................7-23
Magnitude Comparison of Positive-Sequence Current to Negative-
Sequence Current ........................................................................................7-23
Loss-of-Potential Supervision .............................................................................7-24
Single-Pole Open Supervision.............................................................................7-24
Negative-Sequence Directional Element Test Using Single Voltage and Current
Sources ................................................................................................................7-24
Negative-Sequence Directional Element Test Using Three Voltage Sources and
One Current Source.............................................................................................7-27
Phase Mho Distance Elements............................................................................................7-31