Date Code 20011026 Maintenance and Testing 7-57
SEL-321/321-1 Instruction Manual
System Does Not Respond to Faults
1. Relay improperly set.
2. Improper test source settings.
3. PT or CT input cable wiring error.
4. Analog input cable between transformer secondary and main board loose or defective.
5. Failed relay self-test.
Terminal Displays Meaningless Characters
1. Serial communications protocol (baud rate, parity, stop elements) set incorrectly.
RELAY CALIBRATION
The SEL-321 Relay is factory calibrated to a very high degree of accuracy. If you suspect that
the relay is out of calibration, please contact the factory. We can provide instructions for
returning the relay for factory recalibration.
FIRMWARE UPGRADES
SEL may occasionally offer firmware upgrades to improve the performance of your relay. These
instructions explain how to install new firmware.
The modifications require that you power down the relay, remove its front panel, pull out the
drawout unit, exchange one or more integrated circuit (IC) chips, and reassemble the relay. If
you do not wish to perform the modifications yourself, we can assist you. Simply return the
relay and integrated circuit chips to us. We will install the new chips and return the unit to you
within a few days.
CAUTION
!
This procedure requires that you handle electrostatic discharge
sensitive components. If your facility is not equipped to work with
these components, we recommend that you return the relay to SEL for
firmware installation.
Firmware Upgrade Instructions
Step 1. Connect a computer or terminal to the relay serial communications port and enter
Access Level 2. Execute the SHOWSET C and SHOWSET F commands, and
record all displayed data for possible future recalibration. Execute the QUIT
command to leave Access Level 2 and return to Access Level 0.
Step 2. If the relay is in service, disable its breaker control functions. Turn off control
power to the relay. Remove all communications cables from the front- and rear-
panel communications ports. Remove the cable from the IRIG-B input, if one is
installed.
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