U.4.73
Date Code 20090715 User’s Guide SEL-421 Relay
Basic Relay Operations
Configuring High-Accuracy Timekeeping
Firmware version R112 redefines the meaning of the BNC connectors on the
rear panel of the SEL-421. Pay close attention to the following instructions if
you are upgrading your SEL-421 firmware.
Using New SEL-421 Firmware in an Existing Relay
In new SEL-421 relays, the IRIG-B BNC connector is in the same location as
the 1k PPS BNC connector on previous relays. If you upgrade a previously
installed SEL-421 relay to firmware version R112 or later, you will be
provided with a retrofit kit that includes a new rear-panel label for the TIME
inputs (see Figure 4.65). Follow the instructions included in the firmware
upgrade package, and be sure to remove any 1k PPS time source cables that
were previously connected.
Additionally, if the IRIG-B signal was previously supplied to the SEL-421 via
Serial Port 1, and HIRIG mode operation is desired, connect the IRIG-B
source to the IRIG-B BNC connector instead.
Time and Date
Management Settings
Not Required
SEL-421 Relays Changed
Previous firmware versions (R111 and earlier) of the SEL-421 relay provided
Global Settings ETPPS and ETIRIG to enable or disable the 1k PPS and
IRIG-B time sources. Beginning in firmware version R112, these settings are
no longer part of Global Settings, because there is no 1k PPS input connector.
Relay Word bit TPPS has also been removed from the relay.
Connecting
High-Accuracy
Timekeeping
The procedure in the following steps assumes that you have a modern high-
accuracy GPS receiver with a BNC connector output for an IRIG-B signal.
Use a communications terminal to send commands and receive data from the
relay (see Making an EIA-232 Serial Port Connection on page U.4.5).
This example assumes that you have successfully established communication
with the relay (see Making an EIA-232 Serial Port Connection on page U.4.5).
In addition, you must be familiar with relay access levels and passwords (see
Changing the Default Passwords: Terminal on page U.4.9 to change the
default access level passwords).
Step 1. Confirm that the relay is operating (see Connecting and
Applying Power on page U.4.3).
Step 2. Prepare to control the relay at Access Level 2.
a. Using a communications terminal, type ACC <Enter>.
b. Type the Access Level 1 password and press <Enter>.
You will see the Access Level 1 => prompt.
Step 3. Connect the cable.
Attach the IRIG-B signal with a BNC-to-BNC coaxial jumper
cable from the GPS receiver IRIG-B output to the SEL-421
TIME IRIG-B BNC connector (see Figure 4.63).
NOTE: Consult the specific GPS
Clock (IRIG-B time source) instruction
manual for the IRIG-B cable
requirements, termination resistor
requirements, antenna installation,
and clock configuration details.
Courtesy of NationalSwitchgear.com
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