Schweitzer Engineering Laboratories SEL-411L User Manual

Date Code 20150401 SEL Application Guide 2015-12
Application Guide Volume I AG2015-12
Testing a Two-Terminal Application
of the SEL-411L in Test Mode
Ashwin Vashist and George Alexander
INTRODUCTION
The SEL-411L Advanced Line Differential Protection, Automation, and Control System has a
built-in test mode with flexible single-terminal and multiterminal testing options. This mode
allows you to perform acceptance, commissioning, and maintenance testing on a line differential
application that uses SEL-411L Relays in an easy and efficient manner. The TEST 87L
command makes it possible to test the differential element on an in-service line from only one
terminal or from all terminals at the same time (the latter requires the test sets to be satellite-
synchronized).
Figure 1 shows a typical line differential protection arrangement where the exchange of local and
remote operating data between the relays in the scheme takes place over two channels. Bay 1
(Channel 1) uses a dedicated fiber direct connection between the two relays and a channel-based
data synchronization method (ping pong). Bay 2 uses multiplexers to create a hot standby
channel. This has the potential for channel asymmetry, so a time-based synchronization is used
for Channel 2. When external time-based synchronization is used, both SEL-411L Relays must be
connected to an external, high-precision, IEEE C37.118-compliant time source.
This application guide is a test guide for the scenario presented in Figure 1. The goal of this guide
is to provide the ability to test the characteristics of the differential elements in an SEL-411L and
to provide the tools to calculate the currents to be injected into the relay to validate the
differential scheme.
SEL-411L
SEL-411L
Bay 1
Bay 2
Dedicated Fiber
Hot Standby
Channel
Digital
Multiplexer
Digital
Multiplexer
Bay 1
Bay 2
Figure 1 Typical two-terminal SEL-411L application

Schweitzer Engineering Laboratories SEL-411L Specifications

General

Brand	Schweitzer Engineering Laboratories
Model	SEL-411L
Category	Relays
Language	English

Summary

Introduction to SEL-411L Test Mode

SEL-411L Test Mode Overview

Discusses the built-in test mode for line differential applications.

SEL-411L Test Mode Features and Operation

Relay Test Mode Pushbutton Function

Describes the function of the front-panel pushbutton for test mode.

TEST 87L Command Activation

Explains how to activate the TEST 87L command for testing.

Watchdog Error and Channel Health Monitoring

Watchdog Error Handling and Reset

Details watchdog errors, their causes, and reset commands.

Channel Health Verification (87CH1OK)

Explains how to check channel communication status using bit 87CH1OK.

87L Characteristic Test Methods

Single-Terminal Testing Approach

Describes testing at a single terminal with simulated local/remote currents.

Multiterminal Testing Approach

Describes testing at multiple synchronized terminals with actual currents.

Single-Terminal 87L Test Current Injection

Current Injection for 87LA, 87LQ, 87LG

Details injecting currents into IA and IB for specific elements.

Current Injection for 87LB

Details injecting currents into IB and IC for the 87LB element.

Current Injection for 87LC

Details injecting currents into IC and IA for the 87LC element.

Test Procedures: Single and Multiterminal

Test Settings and Data Acquisition

Lists key settings and explains the MET DIF command for test results.

Single-Terminal Test Procedures

Pickup Setting Check (Single-Terminal)

Procedure to check differential element pickup values.

Radius Setting Check (Single-Terminal)

Procedure to verify the Alpha Plane radius setting.

Block Angle Setting Check (Single-Terminal)

Procedure to verify the Alpha Plane blocking angle.

Multiterminal Test Procedures

Pickup Setting Check (Multiterminal)

Procedure to check differential element pickup values in multiterminal mode.

Radius Setting Check (Multiterminal)

Procedure to verify the Alpha Plane radius setting in multiterminal mode.

Multiterminal Block Angle Check

Block Angle Setting Check (Multiterminal)

Procedure to verify the Alpha Plane blocking angle in multiterminal mode.

Conclusion