Date Code 20100129 Instruction Manual SEL-751A Relay
Section 10
Testing and Troubleshooting
Overview
Relay testing is typically divided into two categories:
➤ Tests performed at the time the relay is installed or
commissioned
➤ Tests performed periodically once the relay is in service
This section provides information on both types of testing for the SEL-751A
Feeder Protection Relay. Because the SEL-751A is equipped with extensive
self-tests, traditional periodic test procedures may be eliminated or greatly
reduced.
Should a problem arise during either commissioning or periodic tests, the
section on Troubleshooting on page 10.14 provides a guide to isolating and
correcting the problem.
Testing Tools
Serial Port
Commands
The following serial port commands assist you during relay testing.
The METER command shows the ac currents and voltages (magnitude and
phase angle) presented to the relay in primary values. In addition, the
command shows power system frequency. Compare these quantities against
other devices of known accuracy. The METER command is available at the
serial ports and front-panel display. See Section 7: Communications and
Section 8: Front-Panel Operations.
The relay generates a 15- or 64-cycle event report in response to faults or
disturbances. Each report contains current and voltage information, relay
element states, and input/output contact information. If you question the relay
response or your test method, use the event report for more information. The
EVENT command is available at the serial ports. See Section 9: Analyzing
Events.
The relay provides a Sequential Events Recorder (SER) event report that time-
tags changes in relay element and input/output contact states. The SER
provides a convenient means to verify the pickup/dropout of any element in
the relay. The SER command is available at the serial ports. See Section 9:
Analyzing Events.
Use the TARGET command to view the state of relay control inputs, relay
outputs, and relay elements individually during a test. The TARGET
command is available at the serial ports and the front panel. See Section 7:
Communications and Section 8: Front-Panel Operations.
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