Schweitzer Engineering Laboratories SEL-251 Manuale utente

SEL-251

SEL-251-2

SEL-251-3

DISTRIBUTION RELAY

PHASE OVERCURRENT RELAY

WITH VOLTAGE CONTROL

NEGATIVE-SEQUENCE OVERCURRENT RELAY

GROUND OVERCURRENT RELAY

MULTIPLE SHOT RECLOSING RELAY

SELECTABLE SETTING GROUPS

CIRCUIT BREAKER MONITOR

FAULT LOCATOR

SELOGIC™ CONTROL EQUATIONS

INSTRUCTION MANUAL

SCHWEITZER ENGINEERING LABORATORIES, INC.

2350 NE HOPKINS COURT

PULLMAN, WA USA 99163-5603

TEL: (509) 332-1890 FAX: (509) 332-7990

The software (firmware), schematic drawings, relay commands, and relay messages are copyright protected by the United States Copyright

Law and International Treaty provisions. All rights are reserved.

You may not copy, alter, disassemble, or reverse-engineer the software. You may not provide the software to any third party.

All brand or product names appearing in this document are the trademark or registered trademark of their respective holders.

Schweitzer Engineering Laboratories, Inc., SELOGIC, and are registered trademarks of Schweitzer Engineering Laboratories, Inc.

This product is covered by U.S. Patent Nos: 5,041,737; 5,477,408; 5,479,315; and 5,602,707.

Printed in USA

Date Code 20000421 Manual Change Information i

SEL-251, -2, -3 Instruction Manual

MANUAL CHANGE INFORMATION

The date code at the bottom of each page of this manual reflects the creation or revision date.

Date codes are changed only on pages that have been revised and any following pages affected

by the revisions (i.e., pagination). If significant revisions are made to a section, the date code on

all pages of the section will be changed to reflect the revision date.

Each time revisions are made, both the main table of contents and the affected individual section

table of contents are regenerated and the date code is changed to reflect the revision date.

Changes in this manual to date are summarized below (most recent revisions listed at top).

Revision

Date Summary of Revisions

The Manual Change Information section has been created to begin a record of revisions to

this manual. All changes will be recorded in this Summary of Revisions table.

20000421 Section 2: Specifications:

− Updated to include details for 1-amp nominal current input model.

− Added frequency and rotation information

− Incorporated "New SEL-200 Series Optical Isolator Logic Input Rating"

addendum.

− Combined specifications for Conventional Terminal Block models and Plug-

In Connector models.

− Incorporated "SEL-151/151C/251/251C Instruction Manual Addendum

for 1 Amp Version Relays"

Section 5: Applications

− Added note to Settings Sheets to indicate different setting ranges for 1-amp

nominal current input relays.

Section 6: Installation

− Incorporated "Jumper Installation Instructions" addendum.

− Incorporated "SEL-200 Series (Shallow) Relay Hardware" addendum.

− Added Figure 6.5: LP Relay Dimensions and Drill Plan (for relays with

1-amp nominal current inputs).

Section 7: Maintenance and Testing

− Added note to indicate that the Low-Level Test Interface is not available on

LP chassis relays.

Appendix B

− Added note below Figure B.1 that describes the difference in test point

locations for LP chassis relays.

− Reissued all Appendices.

ii Manual Change Information Date Code 20000421

SEL-251, -2, -3 Instruction Manual

Revision

Date Summary of Revisions

971121 Added Settings Sheets to end of Section 5.

971107 Section 2 - Corrected logic in Figure 2.22.

971028 Section 2 - Corrected Drawings in Figures 2.1 and 2.2.

970418 Appendix A - Added New Firmware Versions.

Date Code 20000421 Table of Contents i

SEL-251, -2, -3 Instruction Manual

SEL-251, -2, -3 INSTRUCTION MANUAL

TABLE OF CONTENTS

SECTION 1: INTRODUCTION

SECTION 2: SPECIFICATIONS

SECTION 3: COMMUNICATIONS

SECTION 4: EVENT REPORTING

SECTION 5: APPLICATIONS

SECTION 6: INSTALLATION

SECTION 7: MAINTENANCE AND TESTING

SECTION 8: APPENDICES

Appendix A: Firmware Versions in this Manual

Appendix B: Main Board Jumper Connector and Socket Locations

Appendix C: Onebus: Program to Compute Test Set Settings for

Testing Distance Relays

Date Code 970103 Table of Contents i

SEL-251, -2, -3 Instruction Manual

TABLE OF CONTENTS

SECTION 1: INTRODUCTION 1-1

Getting Started.............................................................................................................................. 1-1

Overview...................................................................................................................................... 1-1

Conventional Terminal Block Model................................................................................... 1-1

Plug-In Connector Model..................................................................................................... 1-2

General Description: Conventional Terminal Block Model....................................................... 1-2

SELOGIC Control Equations: The Next Step in Programmable Relay Logic ..................... 1-2

Phase, Ground, and Negative-Sequence Overcurrent Protection......................................... 1-2

Sophisticated Multiple-Shot Reclosing Relay Includes Reset Inhibit and Sequence

Coordination................................................................................................................. 1-3

Six Selectable Groups of Settings and Logic....................................................................... 1-3

Circuit Breaker Monitor Tracks Breaker Performance and Helps Maintenance

Planning........................................................................................................................ 1-3

Fault Locator Reduces Line Patrol and Outage Time.......................................................... 1-3

Analyze Operations Using Event Reports............................................................................ 1-3

Comprehensive Metering Supports Protection, Operation, and Demand Analysis ............. 1-3

Access SEL-251 Relay Information via the SEL-RD Relay Display................................... 1-4

General Description: Plug-In Connector Model ......................................................................... 1-4

Wiring Harnesses ................................................................................................................. 1-4

High Current Interrupting Output Contacts.......................................................................... 1-4

Date Code 970103 Introduction 1-1

SEL-251, -2, -3 Instruction Manual

SECTION 1: INTRODUCTION

GETTING STARTED

If you are not familiar with this relay, we suggest that you read this introduction, then perform

the Initial Checkout Procedure in Section 7: Maintenance & Testing.

OVERVIEW

Conventional Terminal Block Model

The SEL-251 Relay is designed to protect distribution lines for all fault types. The following list

outlines protective features, performance, and versatility gained when applying the SEL-251

Relay to your installations.

• Develop traditional and advanced schemes using flexible SELOGICTM Control Equations

• Phase-overcurrent elements have voltage control for load security

• Negative-sequence elements reject load for more sensitive phase fault protection

• Ground and residual overcurrent elements cover ground faults

• Choose fast or electromechanical reset characteristic for time-overcurrent elements

• Overcurrent elements inhibit recloser reset to prevent nuisance "trip-reclose" cycling

• Sequence coordination avoids unnecessary tripping for faults beyond line reclosers

• Undervoltage logic detects high-side transformer fuse operations

• Six selectable setting groups cover all feeder protection contingencies

• Circuit breaker monitor sums interrupted current in each pole to aid maintenance

• Fault locator reduces line patrol and outage time for increased service reliability

• Eleven-cycle event report simplifies fault and system analysis

• Comprehensive voltage, current, power, unbalance, and demand metering

• Connects to SEL-RD Relay Display for easy information access

• Improved Fast Meter

• Improved Fast Operate

The SEL-251 Relay improves every aspect of feeder protection.

• Security: Undervoltage supervision and negative-sequence avoid load encroachment

• Reliability: Field-proven hardware; new backup concepts

• Sensitivity: Negative-sequence overcurrent elements for better phase fault coverage

• Flexibility: SELOGIC Control Equations handle virtually every conceivable scheme

1-2 Introduction Date Code 970103

SEL-251, -2, -3 Instruction Manual

• Capability: Brings transmission relay features to distribution applications

• Economy: Low price and unique features make the relay an exceptional value

Plug-In Connector Model

• All features included in the standard terminal block model

• High current interrupting output contacts

• Quick connect/release hardware for rear-panel terminals

• Time code input access on all rear communications ports

GENERAL DESCRIPTION: CONVENTIONAL TERMINAL BLOCK MODEL

The SEL-251 Relay protects, controls, and monitors distribution feeders. It offers important new

and unique features, like user-programmable SELOGIC Control Equations, negative-sequence

overcurrent elements, and selectable setting groups. The advanced relay design enhances

security, reliability, sensitivity, and operation.

SELOGIC Control Equations: The Next Step in Programmable Relay Logic

In 1987, SEL invented Programmable Mask Logic. The SEL-251 Relay offers SELOGIC Control

Equations, the next step in user-programmability. SELOGIC Control Equations include ANDing,

ORing, and inverting functions, timing, and programmable inputs and outputs. SELOGIC Control

Equations add power and flexibility while simplifying programming.

Phase, Ground, and Negative-Sequence Overcurrent Protection

Phase and negative-sequence overcurrent elements detect phase faults. Negative-sequence

overcurrent elements reject three-phase load to provide more sensitive coverage of

phase-to-phase faults. Phase overcurrent elements are needed only for three-phase faults where

negative-sequence quantities are not produced.

On heavily-loaded feeders, undervoltage torque control of phase overcurrent elements adds

security. Choose between three-phase and single-phase-pair undervoltage torque control. When

phase overcurrent elements are used only for three-phase faults, the three-phase undervoltage

option enhances security.

Ground/Residual overcurrent elements detect ground faults, and external inputs can torque

control selected overcurrent elements.

There are two reset characteristic choices for the time-overcurrent elements. One choice resets

the elements if current drops below pickup for at least one cycle. The other choice emulates

electromechanical induction disc elements where the reset time depends on the time dial setting,

the percentage of disc travel, and the amount of current between zero and pickup.

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