10.13
Date Code 20080918 Instruction Manual SEL-749M Relay
Testing and Troubleshooting
Troubleshooting
Troubleshooting
Refer to Table 10.9 for troubleshooting instructions for particular situations.
Factory Assistance
We appreciate your interest in SEL products and services. If you have
questions or comments, please contact us at:
Schweitzer Engineering Laboratories, Inc.
2350 NE Hopkins Court
Pullman, WA 99163-5603 USA
Phone: +1.509.332.1890
Fax: +1.509.332.7990
Internet:www.selinc.com
E-mail: info@selinc.com
Ta b l e 1 0.9 Tro ub le sh oo ti ng
Problem Possible Cause Solution
The relay ENABLED front-panel LED is
dark.
Input power is not present or a fuse is
blown.
Verify that input power is present.
Check fuse continuity.
Self-test failure. View the self-test failure message on the
front-panel display.
The relay front-panel display does not
show characters.
The relay front-panel has timed out. Press the
{ESC} pushbutton to activate the
display.
The relay is de-energized. Verify input power and fuse continuity.
The relay does not accurately measure
voltages or currents.
Wiring error. Verify input wiring.
Incorrect CTR1, CTRN, or PTR setting. Verify instrument transformer ratios, con-
nections, and associated settings.
Voltage neutral terminal (N) is not prop-
erly grounded.
Verify wiring and connections.
The relay does not respond to commands
from a device connected to the serial port.
Cable is not connected. Verify the cable connections.
Cable is not the correct type. Verify the cable pinout.
The relay or device is at an incorrect baud
rate or has another parameter mismatch.
Verify Device software setup.
The relay serial port has received an
XOFF, halting communications.
Type <Ctrl+Q> to send the relay XON
and restart communications.
The relay does not respond to faults. The relay is improperly set. Verify the relay settings.
Improper test source settings. Verify the test source settings.
Current or voltage input wiring error. Verify input wiring.
Failed relay self-test. Use the front-panel
RELAY STATUS func-
tion to view self-test results.
Courtesy of NationalSwitchgear.com
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