Schweitzer Engineering Laboratories SEL-321 - Cannot See Characters on Relay LCD Screen; No Prompting Message Issued to Terminal Upon Power-Up; Relay Does Not Respond to Commands from Device Connected to Serial Port; Tripping Output Relay Remains Closed Following Fault

7-56 Maintenance and Testing Date Code 20011026
SEL-321/321-1 Instruction Manual
Cannot See Characters on Relay LCD Screen
1. Front panel connector cable is unhooked.
2. Relay is de-energized or turned off.
3. LCD contrast is out of adjustment. Use the steps below to adjust the contrast.
Press the TARGET RESET button to perform an LED lamp test. During the lamp test, the
relay illuminates all 16 front panel LEDs for about one second. The relay also turns on the
LCD back lighting.
Locate the contrast adjust hole in the front panel below the INST LED.
Insert a small screwdriver in this hole to adjust the contrast. Turn clockwise to decrease
contrast and counter-clockwise to increase contrast.
Relay Does Not Respond to Commands From Device Connected to Serial Port
1. Communications device not connected to system.
2. Relay or communications device at incorrect baud rate or other communication parameter
incompatibility, including cabling error.
3. System is processing event record. Wait several seconds.
4. System is attempting to transmit information, but cannot due to handshake line conflict.
Check communications cabling.
5. System is in the XOFF state, halting communications. Type <CTRL>Q to put system in
XON state.
Tripping Output Relay Remains Closed Following Fault
1. Auxiliary breaker contact inputs improperly wired.
2. Improper Trip Unlatch Logic Setting.
3. Output relay contacts welded closed.
No Prompting Message Issued to Terminal upon Power-Up
1. Terminal not connected to relay.
2. Terminal improperly connected to relay.
3. Incorrect terminal serial communications protocol (baud rate, parity, stop elements).
4. Main board failure.